INSIDE THIS ISSUE: Head’s Message Challenge Problems New Faculty/Staff Comings & Goings University of Massachusetts Amherst 2019-2020 Volume 35 Staff Feature Alumni Interview THOUGHTS FROM EMERITUS PROFESSOR FLOYD WILLIAMS Interview with George Avrunin Regarding the recent political unrest in our country that has focused on the issues of racism, black lives, etc, I submit the following thoughts. These are not intended to be political but to express In Memoriam — Jim Humphreys some broader personal concerns as well that in some sense flow beyond the sad, tragic events that transpired in Minnesota — the May 25th 2020 killing of George Floyd. Like so many others, I have Departmental efforts to experienced racial discrimination over the course of many years. This with other ills I see as part promote inclusivity of the general fabric of society that manifests itself in the positive and negative behavior of human Conferences beings. I have tried to use these negatives, coupled with my own personal faults and failures, as Recognizing Student a platform for personal growth. As has well been said, life’s troubles and tragedies can make us Success bitter or better. I realize that numerous other groups suffer as well from discrimination – racial, religious, or otherwise. Whether they be Tibetans, Irish, Christians in Eritrea, Muslims or Indians Sabbatical News in America, or Indians in India by way of Hindu nationalists, the list seems to go on and on. The Donors poignant question that Rodney King asked during the six days of the 1992 LA riots still lingers in the air decades later: “Can’t we all just get along?” When I was asked to speak in Poland for the second time, I took the opportunity to visit both Camp Birkenau and Auschwitz and thus I was able to see first hand the cruel instruments of terror and death imposed by the Nazis on the Jews, Gypsies, Czechs, Yugoslavs, Austrians, Poles, and others. Mathematics and Statistics Article continues on page 6 HABEN MICHAEL INTERVIEW Haben Michael was featured in the last newsletter, as one of three new assistant professors in 2019-20. Hearing of his interesting and non-traditional back story, I interviewed him last summer. — Ed.
MW: Can you give us a summary of your career? HM: I received a BS in Mathematics and a PhD in Statistics, both from Stanford. In between the two I went to law school, worked in mergers & acquisitions for a couple of years, and practiced law for a time. I also worked (and continue to work) in housing court, representing tenants in the Boston area.
MW: What is law school like for someone with a math background? Easier? Harder? Weirder? HM: It was fun, it didn’t feel like work. I was a TV junkie, but rather than watch TV, I would just read cases. The philosophy or policy conversations I had with friends (“is that really legal? but then why is this illegal?”) suddenly had a clear purpose. I would compare the difference between philosophy conversations on the one hand and practicing the law on the other, to the difference between working on a challenging textbook problem and doing research. It’s a different type of intellectual challenge. You don’t encounter the kind of problem you do in math, which hurts your head to even think about too long, the mental equivalent of moving an awkward piece of furniture up a spiral staircase. But in litigation or negotiations there is the challenge of quick thinking, time plays an important role. And there is often another different kind of challenge. It’s doing something that seems simple, and the simple solution will in fact work 98% of the time, but a lawyer is brought in to make sure it goes off without a hitch 99.5% of the time. That requires some thought and imagination One difference is that these challenges seem to ease up with experience. As far as I can tell math doesn’t ever get any easier. By the way, I think nowadays it is much more common to find law students who have a math or related background. The methods of STEM fields have been adopted by the law and legal practitioners just as in many other humanities disciplines.. Article continues on page 11
Department of Mathematics EDITORIAL As I write this, the US presidential election is still weeks away and and Statistics Newsletter the world seems very turbulent and full of suffering. The impact of NEW CHALLENGE PROBLEMS MATHEMATICS & COVID-19 will be felt for a long time to come. In mid-March the Edited By universityHere abruptly is a selection moved to offully some online of instruction, the more and challenging we are still at it.problems Budget problems from have the led 2018 to staff Jacob-Cohen-Killam furloughs and even layoffs, prize STATISTICSMark C. Wilson and thereexam. is noThree end in sight.additional I am confident prize examthat we problemswill weather arethe storm, eventually. Reading of the often difficult lives of famous math- NEWSLETTER included in the Awards Dinner article on page 14... Proofread by ematicians in history helps to give some perspective. Of course, we ...... Maria Dascalu, Jennifer Li & don’t read about the ones who died of some easily preventable disease before they had the chance to achieve great things. EDITED John BY Staudenmayer Problem 1. Compute the volume of the 2018– dimensional simplex Richard S. Ellis Robert Kusner This issue is a little different from usual, for example because various events{( sucht , ... as , thet StudentR2018 Awards ceremonyt were nott held in person. Designed By 1 2018 1 2018 and ...... hence did not yield the usual photos. I have tried to keep some sense of stability among all the instability we are living through, by DESIGNEDAmherst Copy BY & Designworks )∈ : 0 ≤ ≤ ··· ≤ ≤ 1} reverting to a more normal Given production numbers timetable a , a (you, a may, a recall, suppose that last issueProblem was very 2. late). If all has gone well, 1you 2will3 be seeing4 this Brigette McKennaPrinted by issuea justn is before defined Thanksgiving, recursively although as only in electronic form this Amherst Copy & Designworks year.
an = (an−1 + an−2 + an−3 + an−4)/4. INWith COOPERATION special thanks to the named WITH contributors, and those Department members rose to the substantial challenge of remote teaching. Of course, some already had experience. A column in the whose names are forgotten but whose contributions are Show that the sequence {an} converges and Q.Y. CHEN P. FLAHERTYgreatly appreciated. O. GWILLIAM localcalculate Daily Hampshire L = lim Gazettea recently...... made favorable mention of Joanna Jeneralczuk’s coursen→∞ taught n online via the University With- P. HACKING J. HOROWITZ S. HROBAR The Department of Mathematics and Statistics publishes out Walls program. A departmental Slack channel set up to share V. LYZINSKI I. MIRKOVIC A. MORALES its annual newsletter for alumni and friends. You are teachingProblem techniques 3. in Consider the new environment a regular generated tetrahedron a great withcol- laborative spirit and many useful ideas. F. PEDIT important,A. and RAYMOND we want to hear fromC. you! RUSSELL Please contact us edges of length 1. What is the length of the shortest N. WANG at [email protected]. WHITAKER to share yourR. news,YOUNG let us know loop on its surface which surrounds two vertices? .. how you are doing, and learn ways to become involved with Apart from COVID-19, the big domestic news story of the last several the Department. Our website is a valuable resource for months...... has been a renewed emphasis on racial inequality, and in- The Departmentcurrent of happeningsMathematics and news,and soStatistics we encourage publishes you to visit equality more generally. Universities and professional organizations haveProblem certainly been 4. thinking How hardermany about 3×3 inclusion arrays overare thethere last suchfew its annual newsletterus regularly for at alumniwww.math.umass.edu. and friends. Please You send aregeneral feedback to [email protected], and feedback on months.that UMass (i) entries Amherst include has a long all tradition the digits of social from activism 1 through and important, and we wantchallenge to hear problems from you! to [email protected]. Please contact us at progressive9, and thought. (ii) entries One interesting in every data row point and is column the fact (gleaned are in [email protected] to share your news, let us know how fromincreasing Nate Whitaker’s order? article mentioned in this issue) that at his ap- you are doing, and learn ways to become involved with the pointment in the last 1980s he was the third Black professor then Department. Our website is a valuable resource for current in the department, whereas zero or one was a much more common number for a math department in a large research university (even happenings and news, so we encourage you to visit us regularly Problem 5. .Let En be the coefficients in the now the average is less than 1). Some thoughts ∞ xⁿ from onen of the other expansion: .sec x+tan x = E . ⁿ n=0 n! at www. math.umass.edu two, Emeritus Professor Floyd Williams, are included in this issue.
Show that they satisfy E0 =E1 =1 and for n≥1 On a more somber note, we mourn the passing on 2 July Of course, there is always work to be done, and members of our de- partment... have set to it. Some of that work is discussed later in this 2018 of our dear colleague Richard S. Ellis, an internationally issue. regarded probabilist, and a good friend to many of us on Our departmental community sends best wishes for the holidays to campus and in the community. It’s an immeasurable loss to Problem 6. Let An be the set of all subsets S of our Department. For many years Richard edited the annual all students,{1, 2, ..., faculty, n} such staff, that alumni, S contains emeriti and the friends. size |Here’sS| of to S .the Let better world that we can all play our part to create in 2021! Newsletter and monthly News Briefs, and I — your current Bn be the set of all S in An which are minimal, i.e., editor — enjoyed working with him on both for much of the if S contains some subset T in An then T = S. Show
past decade. As I re-drafted the letter soliciting briefs this that the number b of elements of the set B is the Hint: extra letters left over from name anagram name from over left letters extra Hint: n n th September, I realized it was based on Richard’s traditional n Fibonacci number Fn (here F1 = 1 = F2 and after text, passed down from him to me several years ago. Both that Fn = Fn−1 + Fn−2). this Newsletter and the News Briefs have become Department traditions, shaped by each of us who has taken on the role of Problem 7. Evaluate π/2 1 editor, but Richard’s influence looms large. He and I shared many common interests outside mathematics, particularly an intellectual curiosity about languages and literature, and both Send solutions, comments, or feedback via email of us have been deeply committed to carry on the tradition of to Professor Franz Pedit
2 DEPARTMENT HEAD’S MESSAGE DEPARTMENT HEAD’S MESSAGE I’d like to welcome youThe to Departmentour Newsletter of Mathematics as the new and StatisticsDepartment continues Head. to grow I officially and renew itself.started The on number 21 January of Mathematics majors is now over 1000. The most popular concentrations continue to be Actuarial, Computational Math, Statistics and Applied Math. In 2018. It’s a true honor – and somewhat daunting – to follow in the footsteps of Farshid Hajir, who addition, the Department teaches over 15,000 students each year. We hired 10 new faculty members this past year (3 Assistant now serves as ViceProfessors, Provost 5 ofVisiting Academic Assistant Affairs Professors and and did2 Lecturers). a fantastic The job Department in his 3 hasyears a pressing as Head. need Ifor take more over space. The University is a department that’sin the risen planning tremendously stage of renovating in stature 2 wings since in Lederle I came Tower to UMassvacated by in Chemistry 1987. We’ve for the made Department. some exceptional hires and improved our graduate and undergraduate programs. Our graduates have gone on to do outstanding things.This pandemicWe’re very will proudbe considered of our as alumni.a watershed in history when people look back on this time. Our university, our state and much of our nation have stepped up significantly. This pandemic has had a tremendous impact on the University and the Depart- A particular area ment.of growth For the issafety our of number its students of and undergraduate faculty, the University majors, moved which its classes continually to remote inexceeds the middle expectations. of Spring 2020. More This remoteand more of our incoming studentsteaching recognize continued into the Fall benefits 2020. This of wasmajoring a huge adjustment in math. for Weour havefaculty, almost graduate 1000 students majors and staffin 7 thatareas: have Actuarialdone a tremen Science,- dous job that I want to commend them for. I can only see departmental growth from all of these efforts. I am amazed at all of the Applied Math, Computing,sharing and the Pure helping Math, of each Statistics, other from Teaching our marvelous and graduate an Individual students, concentration.staff and faculty. MathematicsThese types of events is alsoare destined an essential to st part of any 21 centuryhappen ineducation, history and aswe overget through 15,000 them UMass by working students as a community take our andclasses supporting each eachyear. other.
Thanks to the hard Onwork top ofof thisour pandemic,search committee, the George Floydour tenureincident trackand the positionillumination in ofMath racial Biology injustice movedwas filled the University by our andtop especandidate:- Assistant Professorcially Brian our Department Van Koten to haveis an discussions expert in and applied take actions probability relating to and inequities numerical in our discipline. analysis, I amperforming very proud ofcomputer the efforts of simulations of molecularmy Department. systems I am with an African-American applications in who biology, grew of chemistryin the 1950s and 1960s materials in the south.science. I lived We during also hadthe transition a very successful from year in hiring 8 newsegregation outstanding and Jim CrowVisiting laws. Assistant When I was Professors: a very young boy,Siddhant my family Agrawal went to a drive-in, Panagiota theatre Birmpa every Sunday, Noriyuki with a fence Hamada down , Kuan-Wen Lai, Jonathanthe middle separatingSimone, whites Zahra and Sinaei blacks, with Zheni separate Utic concession and Jiayu stands. Zhai I have. Our seen new many Marshall changes in Stone our country VAP, since Laura then, Colmenarejo but racism and inequities still persist. Nevertheless, I am very proud to be a part of this Department. When I came to the University Hernando, will join33 years us inago, Spring I was the 2019. third African-American faculty member along with Don St. Mary and Floyd Williams. Especially then and even now, most Math Departments have no African-American faculty. I follow in the footsteps of Don St. Mary as the second Af- Our Newsletter, andrican-American the on-line Department Faculty NewsHead. This Briefs is even at www.math.umass.edu,rarer and I thank the Department provide for their an opportunitysupport and their to trust highlight in me. some of the outstanding work of our faculty in pushing the envelope of knowledge in mathematics and statistics each year: Assistant Professor Nestor GuillenI have beenspoke around at the much Austin longer workshop than most. I also“Gerrymandering grew up in a time when Steals things Elections: were unsettling Learn for how me andIt’s thoseDone who and looked How to Stop It,” and was likepart me, of anda panel they still on arethe in topic many includingways. Nevertheless, US Representative I believe that it isJim very McGovern important to thislook atyear; the silverAssociate lining inProfessor things. We Paul Hacking was invitedmay haveto lecture no control at theover 2018things Internationaloutside of our bodies Congress but we doof haveMathematicians; some control over Associate how we react Professor to them. Life Alexei always Oblomkov has its was awarded a Simonsups Fellowship; and downs for Professors everyone. It Markosis important Katsoulakis to try to adapt and to this Luc time Rey-Bellet and be optimistic. received Take a advantage major Air of extra Force time grant and try to to develop accomplish things that you did not have time to do before. This pandemic will end and I believe that we would be very happy to look performance guaranteesback and seein howpredictive we took advantagemodeling; of this Professor time in some Andrea way. The Nahmod pandemic was has partmade ofus aappreciate feature the honoring simple things women in life inmore. the Notices of the AMS; and UniversityI cannot wait Distinguishedto have coffee with Professor a friend, workPanos side Kevrekidisby side with someone published on a math4 papers problem in or the just Nature pass someone family in theof journals.hall and say hello. Be safe and optimize the moment!! — Nate Whitaker Our Department hosted 3 conferences this past year: Associate Professor Anna Liu was among the organizers of the 32nd New England Statistical Symposium bringing together nearly 250 statisticians to discuss emerging issues in April 2018; Professor Andrea Nahmod helped organize Women in Partial Differential Equations in March 2018; and Associate Professor Hongkun Zhang co-organized Mathematical Physics Perspective of Billards and Dominoes celebrating the 70th birthdays of Pavel Bleher and Leonid Bunimovich in September 2017.
UMass Amherst undergraduates Jonah Chaban, Artem Vysogorets, and Jimmy Hwang worked as a team, led by Assistant Professor Matthew Dobson, to produce the top-scoring project among 7 competing teams at the first ever Student Competition Using Modeling (SCUDEM) in Fall 2017. Three more SCUDEM teams led by Dobson also did very well in Spring 2018, receiving meritorious mention and outstanding mention.
We are very sad to have lost an important member of our faculty, Richard S. Ellis, who passed away in July 2018. Richard joined the department in 1975, and also taught classes in Judaism and the Torah as an adjunct professor of Judaic and Near Eastern Studies. He was an internationally regarded expert in probability and large deviation theory, who also cared very much about the well-being of his students and colleagues, organizing sessions to relieve stress both inside and outside of the classroom. Richard will be truly missed. 2019-2020 Volume 35 3 We are also sorry to report the retirement of two important members of our faculty, Michael Lavine and Bill Meeks, in May 2018. Professor Lavine, a well-respected Bayesian statistician and a leader in our statistics group, had been a department member since 2008. Professor Meeks held the prestigious George David Birkhoff chair since joining the department in 1986; he is a world-renowned differential geometer and topologist, with a distinguished reputation in the area of minimal surfaces.
The support of our alumni and friends is invaluable to us. We want to know how you are doing. Please send us your news, or stop in for a visit.
– Nathaniel Whitaker
DEPARTMENT OF MATHEMATICS & STATISTICS 2018 Volume 33 3
3
2020 PROBLEM CHALLENGE PREVIEW OF ARTICLE IN NOTICES OF THE AMERICAN 1. In base-2020, the number 2020! = 2020 2019 2 1 ends MATHEMATICAL SOCIETY · ··· · with how many zeroes? NEW CHALLENGE PROBLEMS MATHEMATICS & Nate Whitaker has given public talks 2. Find the average of the squared-distance P Q 2Herebetween is a selection(well received of some by studentsof the morein particular) challenging about STATISTICSall pairs of points P, Q on the unit-radius|| sphere− || Sproblems2 R3. fromhis the life story.2018 Now Jacob-Cohen-Killam he has written an article prize to exam.⊂ Three appearadditional in the Februaryprize exam 2021 problemsissue of Notices are 3 NEWSLETTER3. Let K be the set of 27 points in R of the form (xincluded1,x2,x3) in theof theAwards American Dinner Mathematical article Society on page (which 14. .. with x = 0 or 1. What is the smallest number of planes will be freely available online). i ...... perpendicular to± the coordinate axes and disjoint from K It begins as follows — see the full article EDITEDthat can BY be removed from R3 so that each remaining com- . Compute the volume of the 2018– Problem 1 when it comes out. Personally, I found the ponent of space contains exactly one point of K? dimensional simplex Richard S. Ellis Robert Kusner story extremely interesting, and in places very 3 moving.2018 — Ed 4. Fix a, b, c 0, and consider the space curve C{(t1, ...R , t2018 R t1 t2018 . ≥ 2 3 ⊂ parametrized by C(t)=(at, bt , ct ) for t>0...... Let P (t) As we stood at Fort Monroe at 6AM, DESIGNEDbe the plane BY normal (perpendicular) to C at the point C(t), )∈gazing into : 0 the≤ sea, ≤ I ···could ≤ imagine ≤ the 1} ships
and let V (t) be the volume of the solid bounded byProblemP (t) and 2. approaching,Given numbers bringing a 1,the a2 ,first a3, a 4Africans, suppose to Brigettethe McKenna three coordinate planes. If the limit of V (t)a as ist defined0 whatrecursively would become as this country, bringing my n → equals 1, then what does the product abc equal? own ancestors. My wife and I had traveled to a = (a +Fort a Monroe + a in +Hampton, a )/4. Virginia on August 5. Given a positive integer n, determine all possible positiven n−1 24, n−22019 to n−3observe n−4the 400th anniversary of IN COOPERATION WITH values of x such that this arrival. Amazingly, this site was only Show that thethree sequence miles from {an where} converges I grew up. and It is also the n 2n Q.Y. CHEN P. FLAHERTY O. GWILLIAM calculate L = limcity wherea .the ...... Black women mathematicians (x + i)2 = (x + i)2. n→∞ n P. HACKING J. HOROWITZ S. HROBAR in the book and movie Hidden Figures lived i=0 i=n+1 V. LYZINSKI I. MIRKOVIC A. MORALES and worked. Their stories were hidden as Problem 3. were Consider the stories a regular of the tetrahedrontriumphs of many with F. PEDIT 2 A.6. RAYMOND Can all 3 vertices ofC. anRUSSELL equilateral triangle in R edgeshave of in- lengthAfrican 1. What Americans. is the lengthDuring ofmuch the shortestof my N. WANG N. WHITAKERteger coordinates?R. How YOUNG about all 4 vertices of a regular time navigating the White world as a 3 loop on its surface which surrounds two vertices? .. tetrahedron in R ? mathematician, I myself have felt hidden and ...... invisible. This invisibility is what the narrator 7. For each n =1, 2, 3,..., define the subset X of the unit in- The Department of Mathematics and Statistics publishes n Problem 4. inHow Ralph many Ellison’s 3×3 landmark arrays book are The there Invisible such terval [0, 1] as the following union of closed intervals: Xn = Man feels. He is a Black man who feels its annual newsletter for alumni1 2and3 friends.2n You2 2n are1 that (i) entries include all the digits from 1 through [0, 2n ] [ 2n , 2n ] [ 2−n , 2−n ]. Each Xn has total length invisible to Whites as he maneuvers through important, and we want to hearX fromequal∪ you! to 1Please∪···∪. Find contact the total us lengthat Y of the difference9, and (ii) entries in every row and column are in [email protected] to share| n| your news,2 let us know how | n| their world. This invisibility to the White set Yn = X2n 1 X2n. increasing order?world can also be a handicap when trying to − \ you are doing, and learn ways to become involved with the further one’s education or academic career, 8. Consider the set of all even-sized subsets, and the set Department. Our website is a valuable resourceE2020 for current since the support from your fellow students happenings and news, so we encourage2020 of all youodd-sized to visit subsets,us regularly of the set 1, 2, 3,...,Problem2020 . 5. .andLet facultyEn be thecan coefficientsmake a huge difference in the in O { } ∞ xⁿ n Construct an explicit 1-to-1 function from 2020 ontoexpansion:2020. .sec x+tan x = E . ⁿ n=0 n! at www. math.umass.edu O E your success. The combination of the recent death of George Floyd and the COVID-19 Show that pandemicthey satisfy has somewhat E0 =E1 =1 uncloaked and for or n made≥1 On a more somber note, we mourn the passing on 2 July ... visible the plight of African Americans and 2018 of our dear colleague Richard S. Ellis, an internationally sparked interest in their hidden history. This regarded probabilist, and a good friend to many of us on is the story of my journey from segregation to becoming the Head of the mathematics and campus and in the community. It’s an immeasurable loss to Problem 6. Letstatistics An bedepartment the set atof a allmajor subsets R1 university. S of our Department. For many years Richard edited the annual {1, 2, ..., n} such that S contains the size |S| of S. Let
Newsletter and monthly News Briefs, and I — your current Bn be the set of all S in An which are minimal, i.e., editor — enjoyed working with him on both for much of the if S contains some subset T in An then T = S. Show past decade. As I re-drafted the letter soliciting briefs this that the number bn of elements of the set Bn is the 4 DEPARTMENT OF MATHEMATICS & STATISTICS th September, I realized it was based on Richard’s traditional n Fibonacci number Fn (here F1 = 1 = F2 and after text, passed down from him to me several years ago. Both that Fn = Fn−1 + Fn−2). this Newsletter and the News Briefs have become Department traditions, shaped by each of us who has taken on the role of Problem 7. Evaluate π/2 1 editor, but Richard’s influence looms large. He and I shared many common interests outside mathematics, particularly an intellectual curiosity about languages and literature, and both Send solutions, comments, or feedback via email of us have been deeply committed to carry on the tradition of to Professor Franz Pedit
2 SOLUTIONS TO 2019 CHALLENGE PROBLEMS DEPARTMENT HEAD’SSolution MESSAGE 1. Firstly, we need to impose conditions that guarantee existence of logarithms: a>0, a = 1 and6 x 5 18 > 0. The last inequality is equivalent to 6 x 5 18 = 0, which in turn is | − |− | − |− I’d like to welcome you to our Newsletter as the new Department Head. I officially started on 21 January2 equivalent to x = 2,x = 8. The given equation can be rewritten as loga 6 x 5 18 = loga 72a , | − |− 2018. It’s a true honor – and somewhator equivalently daunting – to follow in the footsteps of Farshid Hajir , who 6 x 5 18 = 72a2. now serves as Vice Provost of Academic Affairs and did a fantastic| − |− job in his 3 years as Head. I take over a department that’s risen tremendouslySo we in need stature to find all since values ofI thecame parameter to UMassa>0, a in= 1,1987. for which We’ve the equation made6 x some5 18 = | − |− 72a2 has exactly two solutions. This equation is satisfied if either 6 x 5 18 = 72a2 or exceptional hires and improved our graduate and undergraduate programs. Our graduates have gone on 6 x 5 18 = 72a2. The first equation, 6 x 5 = 72a2 + 18, always| has− two|− solutions. The to do outstanding things. We’re very secondproud| − |− equation, of our− 6 x alumni.5 = 18 72a2, doesn’t| − have| any solutions if and only if 18 72a2 < 0, i.e. a > 1 . Since| we− also| have− that a>0, a = 1, we see that the original equation− has exactly | | 2 two solutions if and only if a > 1 , a>0, a = 1. Equivalently,1 k1 k1 1 k k 1 1 1 n Using Modeling (SCUDEM) in Fall 2017. Threeφ(n)=( p morep SCUDEM− ) ...(p s p teamss− )=n led1 by Dobson... 1 also did. very well in Spring 2018, 1 − 1 s − s − p − p ≥ 2s 1 s receiving meritorious mention and outstandingNote that mention. n s ln = k ln(p )+...+ k ln(p ) s ln(2) = (k ln(p ) ln(2)). 2s 1 1 s s − i i − i=1 We are very sad to have lost an important member of our faculty, Richard S. Ellis , who passed away in July 2018. Richard joined For every ρ>0, there exists >0 such that if n>then either ps >ρor k1 +...+ks s>ρ. In the department in 1975, and also taught classes inn Judaism and the Torah as ann adjunct professor− nof Judaic and Near Eastern the first case, ln s > ln(ρ) ln(2). In the second case, ln s >ρln(2). Thus lim ln s = 2 − 2 n 2 . →∞ Studies. He was an internationally regarded∞ expert in probability and large deviation theory, who also cared very much about the well-being of his students and colleagues, organizing sessions to relieve stress both inside and outside of the classroom. Richard will be truly missed. 2019-2020 Volume 35 5 We are also sorry to report the retirement of two important members of our faculty, Michael Lavine and Bill Meeks, in May 2018. Professor Lavine, a well-respected Bayesian statistician and a leader in our statistics group, had been a department member since 2008. Professor Meeks held the prestigious George David Birkhoff chair since joining the department in 1986; he is a world-renowned differential geometer and topologist, with a distinguished reputation in the area of minimal surfaces. The support of our alumni and friends is invaluable to us. We want to know how you are doing. Please send us your news, or stop in for a visit. – Nathaniel Whitaker DEPARTMENT OF MATHEMATICS & STATISTICS 2018 Volume 33 3 3 THOUGHTS FROM EMERITUS PROFESSOR FLOYD students and mathematicians who have been mentors to them, WILLIAMS Continued and to me — here I speak not as an expert on a broader area of racism in mathematics. I grew up with no mathematics heroes, The visits there, and visits to the homes of Gandhi in Mumbai, NEWbut only CHALLENGEsports or music persons PROBLEMS to emulate. I knew of the India, Saint Mother Teresa in Calcutta, Einstein in Bern, courageous sports executive Branch Rickey who helped to break MATHEMATICSSwitzerland, Dostoyevsky in St. Petersburg,& Russia, etc, all have Herethe color is abarrier selection in major of league some baseball of the by more signing challenging the gifted helped me to see the world in a broader view — in a vision that problemsblack player fromJackie Robinsonthe 2018 in Jacob-Cohen-Killam 1947. The Branch Rickey typeprize STATISTICSin the short life we occupy on this planet we are admonished to exam.for me, Threeso to speak, additional was Prof. Isadorprize Hirschmannexam problems who broke are seek the humanity and value of all persons, regardless of creed NEWSLETTER a color barrier by admitting me as the first doctoral student in or cultural distinction. Gandhi’s movement of non-violence included in the Awards Dinner article on page 14... the Washington Univ. Mathematics Department. It was actually which culminated in 1947 with independence from Britain ...... music that kept me from dropping out of high school. There I was the template used by Martin Luther King, Jr. Einstein EDITED BY Problemhad the wonderful 1. Compute support andthe investmentvolume of of the many 2018– other labored unceasingly as a champion of human rights. The Space Professors, including Prof. Ed Nussbaum who made such an X astronauts that docked a few days ago with the International dimensional simplex Richard S. Ellis Robert Kusner important contribution to my mathematics learning, along with Space Station viewing our little blue planet from their vantage 2018 {(myt1 thesis, ... , tadvisor2018 RayR Kunze. I wast1 also very tfortunate2018 to .have point reminded us again that ours is a shared atmosphere and a Prof. Bertram Kostant as my MIT Postdoc mentor. My point is shared place in this universe, and hence for the good of all we do ...... DESIGNED BY that many minority)∈ students : 0 ≤have less≤ ··· preparation ≤ ≤sometimes 1} need to “get along together”, as Rodney King so wished. for rigorous classroom Given courses. numbers We often a ,deal a , witha , abasic, suppose survival Whether we go through the pandemic of a Problem 2. 1 2 3 4 Brigette McKenna amatters is defined under conditions recursively of poverty as and racism, with mainly virus or seemingly unsurmountable challenges sportn or entertainment figures for role models. It is very helpful of race relations, we all share a common to havea =Professors (a + anot take + a a negative + a attitude)/4. nor devalue or earthbound destiny. underestimaten n−1 the potentialn−2 ofn−3 these andn−4 other students. IN COOPERATION WITH I feel that if educators see themselves more as There is worldwide agreement that what happened to Show that the sequence {a } converges and George Floyd in our country was absolutely horrific and unjust. serving the needs of studentsn and providing Q.Y. CHEN P. FLAHERTY O. GWILLIAM calculate L = lim a ...... I think we all agree and hope for and would want to see progress mentorship, whenn→∞ possible,n rather than being P. HACKING J. HOROWITZ S. HROBAR towards better training, better community relations, etc, and to “lords” in the class room, then possibly the V. LYZINSKI I.see MIRKOVIC the good riddance to anyA. and MORALES all police persons not worthy amount of discrimination might be lowered. of the badge they wear. I personally have no animus for police Problem 3. Consider a regular tetrahedron with F. PEDIT A. RAYMOND C. RUSSELL I did spend ten years as a member of the New England Board (nor for any group) and I would not paint them all with the same edges of length 1. What is the length of the shortest on Higher Education working with other mathematicians and N. WANG N.brush WHITAKER unfairly. Nor did I paintR. with YOUNG the same brush unfairly all loop on its surface which surrounds two vertices? .. scientists in the grand effort to reach and mentor, and to recruit in the same race as the person by whom I was assaulted and underrepresented students. I also worked with Phil Kutzko robbed on the streets of St. Louis some years ago. My nephew is ...... in Iowa on a project in Florida, and in Valparaiso, Chile, and The Department of Mathematicsa policeman/detective, and Statistics and I have notedpublishes his bravery and fidelity Problem 4. How many 3×3 arrays are there such I worked with Bonita Ewers at Johnson C. Smith University its annual newsletter withfor thatalumni of other and men friends.and women Youthat place are their lives on the that (i) entries include all the digits from 1 through in North Carolina, for example. Many other mathematicians important, and we want toline hear daily from in service you! to others Please in assistingcontact and us saving at lives. In some 9,like and Paul (ii) Sally entries and Ken in Gross every have row also and dedicated column much are time in small ways I have tried to bridge racial and cultural divides in my [email protected] to share your news, let us know how increasingand effort to order?mentoring minority and other underrepresented volunteer work in various local communities. The work includes you are doing, and learn ways to become involved with the groups of students to open doors of mathematics to them. weekly visits to about six different Nursing Homes (which host I think we all hope for some good ends to emerge from Department. Our websiteonly is about a valuable 1% of African resource American for patients),current playing the piano, the tragedy of George. .Let Floyd.E be While the coefficients focused on that tragedyin the we happenings and news, so andwe encourageassisting patients you towith visit hospital us regularly rides for cancer or other Problem 5 n also need to be mindful of the hundreds ∞ xⁿ of weeklyn shootings in at www. math.umass.edutreatments. I also invest time helping two children (ages 5 and expansion: .sec x+tan x = E . ⁿ n=0 n! Chicago (and in other cities ) – of victims that include children 7) with reading challenges, and I work with bi-racial families and Showbabies thethat fate they of whose satisfy black E lives =E does =1 not and always for ngarner≥1 that have experienced discrimination. Thus I believe in using 0 1 the commensurate national and world attention, and action. We On a more somber note,the we many mourn blessings the that passing God has grantedon 2 Julyto me to be a blessing ... are bound by a common destiny on this small blue planet. 2018 of our dear colleagueto others,Richard and S. thus Ellis, to attempt an internationally to see the humanity, value, and When Francis Bacon described the aim of regarded probabilist, andneeds a goodof others, friend in contrast to many to being of wrapped us on up in myself with prejudice and misunderstandings of persons so different from science as to “enlarge the bounds of the campus and in the community. It’s an immeasurable loss to Problem 6. Let A be the set of all subsets S of myself. human empire,” hen expressed the great hope our Department. For many Iyears now mentionRichard some edited of my the experiences annual with minority {1, 2, ..., n} such that S contains the size |S| of S. Let Newsletter and monthly News Briefs, and I — your current Bn be the set of all S in An which are minimal, i.e., editor — enjoyed working with him on both for much of the if S contains some subset T in An then T = S. Show past decade. As I re-drafted the letter soliciting briefs this that the number bn of elements of the set Bn is the 6 DEPARTMENT OF MATHEMATICS & STATISTICS th September, I realized it was based on Richard’s traditional n Fibonacci number Fn (here F1 = 1 = F2 and after text, passed down from him to me several years ago. Both that Fn = Fn−1 + Fn−2). this Newsletter and the News Briefs have become Department traditions, shaped by each of us who has taken on the role of Problem 7. Evaluate π/2 1 editor, but Richard’s influence looms large. He and I shared many common interests outside mathematics, particularly an intellectual curiosity about languages and literature, and both Send solutions, comments, or feedback via email of us have been deeply committed to carry on the tradition of to Professor Franz Pedit 2 that the understanding of nature would NEW FACULTY DEPARTMENT HEAD’Spromote humanMESSAGE welfare. Martina Rovelli will join the I’d like to welcome youOn tothe our other Newsletter hand, we must as the be reminded,new Department as Gauss was, Head. I officially startedDepartment on 21 asJanuary an Assistant Professor 2018. It’s a true honorof the –limitations and somewhat of science. daunting Leibnitz – and to followKant rebuked in the footsteps of Farshidin Hajir January, who 2021. She received a PhD in now serves as Viceattempts Provost by Hobbes,of Academic Laplace Affairs and Voltaire and todid reduce a fantastic humans job in his 3 years as mathematicsHead. I take from over École Polytechnique to a meaningless concourse of atoms devoid of a morality base. Fédérale de Lausanne in 2017, followed a department that’sWithout risen a tremendously moral core we become in stature as “they since who Icut came the stones, to UMass in 1987. We’ve bymade postdocs some at Johns Hopkins University, exceptional hires butand cannot improved truly lay our them, graduate seekers andbound undergraduate to their own tasks, programs. Our graduatesMathematical have gone Sciences on Research Institute to do outstandingeach things. following We’re his ownvery quest, proud his (perverted)of our alumni. fragment of truth” and Australian National University. Her research interests lie at the — quoting from Goethe’s Book of the Earth II. intersection of algebraic topology, higher category theory, and — Floyd Williams A particular area of growth is our number of undergraduate majors, whichhomotopy continually theory. The exceeds collection expectations. of all mathematical More objects and of morea of our incoming students recognize the benefits of majoring in math. givenWe have kind, almost such as sets1000 with majors a certain in algebraic 7 areas: structure Actuarial or state Science, Applied Math, Computing, Pure Math, Statistics, Teaching and an Individualspaces and concentration. the time evolutions Mathematics between them, is often also anassemble essential part of any 21st centuryMATHEMATICAL education, as CULTUREover 15,000 UMass students takenaturally our classes into aeach higher year. category, and higher category theory provides the tools and the necessary language to express and MATH 370 (Junior Year Writing) is an unusual course – understand how the examples of interest from different areas Thanks to the hardrelatively work few of universitiesour search offer committee, such a course, our let tenure alone trackmake it positioninteract within eachMath other.Biology She developswas filled foundational by our aspectstop candidate: of Assistant Professorcompulsory, Brian Van as it Kotenhas been is at anUMass expert Amherst in applied since 1982. probability Along higher and category numerical theory, analysis, and studies performing how different computer models and simulations of molecularwith the usual systems mundane with but applications useful topics such in biology,as mathematical chemistry approaches and materials are related. science. We also had a very successful typesetting, reading and writing papers, and producing a year in hiring 8 new outstanding Visiting Assistant Professors: Siddhant Agrawal, Panagiota Birmpa, Noriyuki Hamada, CV, there is scope for the instructor to expose students to Yulong Lu joined the department as Kuan-Wen Lai, Jonathanmathematical Simone culture., FranzZahra Pedit Sinaei has taken, Zheni students Utic to andthe art Jiayu Zhai. Our new anMarshall Assistant Stone Professor VAP, inLaura September Colmenarejo Hernando, will joinmuseum, us in while Spring my tastes 2019. run more to jokes and songs. Below are 2020. His research interests lie broadly some jokes (none original to me, alas) from a list I use to lighten the in the areas of applied analysis, applied Our Newsletter, andmood the just on-line before plunging Faculty into News another Briefs Zoom at session www.math.umass.edu, where the provide anprobability opportunity and statistics. to highlight He is mainlysome of the outstanding workstudents of areour confronted faculty inwith pushing my pedantry the andenvelope punctiliousness. of knowledge in mathematicsinterested and statistics in developing each year:analytic Assistant and — Mark C. Wilson probabilistic tools for understanding Professor Nestor Guillen spoke at the Austin workshop “Gerrymandering Steals Elections:problems Learn from how physics It’s Done and andmachine How to Stop It,” and was part of a panel on the topic including US Representative Jim McGovernlearning. this year; Associate Professor Paul Hacking was invitedQ: Why to dolecture they never at the serve 2018 beer International at a math party? Congress of Mathematicians; Yulong received Associate his PhD Professor in Mathematics Alexei and StatisticsOblomkov was A: Because you shouldn’t drink and derive. awarded a Simons Fellowship; Professors Markos Katsoulakis and Lucfrom Rey-Bellet the University received of Warwick a major in 2017 Air under Force the grantsupervision to develop of Andrew Stuart and Hendrik Weber. Prior to joining UMass, performance guaranteesQ: What’s in purple predictive and commutes? modeling; Professor Andrea Nahmodhe was awas Research part ofAssistant a feature Professor honoring at the womendepartment in theof Notices of the AMS; and UniversityA: An abelian Distinguished grape. Professor Panos Kevrekidismathematics published at 4 Duke papers University. in the Nature family of journals. Our Department Q:hosted How do 3 youconferences tell whether thisa play past is abelian? year: Associate Professor Anna Liu wasWei among Zhu joined the organizers the department of the as 32an nd New England StatisticalA: Symposium If all of the characters bringing are onetogether dimensional. nearly 250 statisticians to discuss emergingAssistant issues Professor in April in September 2018; Professor 2020. His research is mainly motivated by the Andrea Nahmod helped organize Women in Partial Differential Equations in March 2018;open and challenges Associate in data Professor science including Hongkun Zhang co-organizedQ: Why Mathematical did the chicken Physics cross the Perspective Moebius strip? of Billards and Dominoes celebrating the 70th birthdays of Pavel Bleher and A: To get to the same side. the mathematical understanding of deep Leonid Bunimovich in September 2017. neural networks and designing provably efficient machine learning models for UMass Amherst undergraduates Jonah Chaban, Artem Vysogorets, and Jimmy Hwangthe worked small/corrupted as a team, data led regime. by Assistant He is particularly interested in exploiting Professor Matthew Dobson, to produce the top-scoring project amongthe 7 symmetrycompeting and teamslow-dimensional at the first geometry ever withinStudent the dataCompetition Using Modeling (SCUDEM) in Fall 2017. Three more SCUDEM teamsto ledimprove by Dobson the interpretability, also did verystability, well reliability, in Spring and 2018 data-, receiving meritorious mention and outstanding mention. efficiency of deep learning. Wei received his PhD in applied math from UCLA under the supervision of Stanley Osher. Before joining UMass, We are very sad to have lost an important member of our faculty, Richardhe was S. a EllisPhillip, who Griffiths passed Research away inAssistant July 2018. Professor Richard in the joined the department in 1975, and also taught classes in Judaism and the TorahDepartment as an adjunct of Mathematics professor at Duke of University.Judaic and Near Eastern Studies. He was an internationally regarded expert in probability and large deviation theory, who also cared very much about the well-being of his students and colleagues, organizing sessions to relieve stress both inside and outside of the classroom. Richard will be truly missed. 2019-2020 Volume 35 7 We are also sorry to report the retirement of two important members of our faculty, Michael Lavine and Bill Meeks, in May 2018. Professor Lavine, a well-respected Bayesian statistician and a leader in our statistics group, had been a department member since 2008. Professor Meeks held the prestigious George David Birkhoff chair since joining the department in 1986; he is a world-renowned differential geometer and topologist, with a distinguished reputation in the area of minimal surfaces. The support of our alumni and friends is invaluable to us. We want to know how you are doing. Please send us your news, or stop in for a visit. – Nathaniel Whitaker DEPARTMENT OF MATHEMATICS & STATISTICS 2018 Volume 33 3 3 COMINGS AND GOINGS worked as a graduate assistant for the RCF, and chose to join the team full- Details of the three new Assistant Professors are above. time as an EDP Programmer upon her NEWgraduation CHALLENGE in 2019. She received PROBLEMS her The department welcomes five new Visiting Assistant undergraduate degree in Astronomy MATHEMATICSProfessors: Theodosios (Theo) & Douvropoulos, Vefa Goksel, Hereand Mathematicsis a selection from of some Wesleyan of the more challenging Navid Mohammad Mirzaei, Charles Ouyang, and Yuegiao problemsUniversity, where from she the began 2018 building Jacob-Cohen-Killam an prize STATISTICSZhang. Daniel Ecaizabarrena is now working with Andrea interest in data science and software. In Nahmod as a postdoc. exam.addition Three to continuously additional learning prize about exam problems are NEWSLETTER includednew technologies in the to Awardssupport the Dinner mathematics article department, on page she 14. .. Also welcomed are new Permanent Lecturers: Eric Sarfo ...... currently manages the new RCF computing cluster and assists Amponsah, and Shai Gorski (Mt Ida campus). in the implementation of IT infrastructure. She can be spotted EDITED BY Problemjogging across 1 .Amherst Compute as she the waits volume for rec sportsof the leagues 2018– to Terry Mullen had been in a temporary departmental assistant dimensionalsafely open up again! simplex Richard S. Ellisposition for 18Robert months, andKusner is now in a permanent role of Academic Program Manager. 2018 {(t1, ... , t2018 R Renatot1 Spacek tis2018 the current. graduate student assistant for the Ivan Mirkovic and Brian Burrell each took advantage of the ...... RCF. He received a dual degree DESIGNEDuniversity’s budget-driven BY Voluntary Separation Incentive )∈ : 0 ≤ ≤ ··· ≤ ≤ 1} in Mathematics and Chemical Program to retire earlier than expected. Ivan will remain active Problem 2. Given numbers a , a , a , a , suppose Engineering from1 2 UMass,3 4 before Brigettein research McKenna and supervising graduate students. an is defined recursivelystarting as his Masters degree in Applied Mathematics in 2019. His interests Nestor Guillen has resigned from the department to seek his a = (a + a +lie a in +analysis a )/4. and computational fortune in Texas, and we wish him well. n n−1 n−2 n−3 n−4 IN COOPERATION WITH research. For the RCF, Renato helps with various production tasks and responds to support help requests. Show that the sequence {an} converges and Q.Y. CHEN P. FLAHERTY O. GWILLIAM STAFF FEATURE calculate Alan says L = “The limn→∞ RCF an .has ...... been focused on keeping our P. HACKING J. HOROWITZ S. HROBAR department servers safe and secure during this time of increased The Research Computing Facility (RCF) manages the V. LYZINSKI I. MIRKOVIC A. MORALES online activity. Our external services experience thousands of infrastructure and endpoint systems for the Department of Problemdaily attacks and3. Consideractive measures a regular are constantly tetrahedron being taken with to F. PEDIT A.Mathematics RAYMOND & Statistics. WeC. supportRUSSELL 344 active department edgeskeep your of lengthaccounts 1. and What data issafe. the Throughout length of the the transition shortest users, comprising 120 faculty members, 36 visiting academics, N. WANG N. WHITAKER R. YOUNG loopto remote on itslearning, surface the whichRCF has surrounds adapted in order two tovertices? provide .. 160 graduate students, and 28 staff members, as well as over remote assistance to our faculty and staff. We have deployed 1000 undergraduate students. a department VPN, so that our staff can continue with their The RCF is composed of Alan Boulanger, Rachel Aronow, ...... The Department of Mathematics and Statistics publishes familiar workflows while off-site (any department members and graduate student assistant Renato Spacek. Problemwho believe they 4. wouldHow benefitmany from3×3 arraysutilizing arethe thereVPN should such its annual newsletter for alumni and friends. You are thatreach (i) out entries to us via include email to all request the digitsaccess). from We respond 1 through to important, and we want to hear from you! Please Alan contact Boulanger us atis the acting Direc- 9,email and help (ii) requests entries and in have every been row utilizing and Zoomcolumn and remoteare in [email protected] to share your news,tor let of us Research know Computing how and joined screen sharing technologies to provide hands-on support for the department in 2008. Prior to joining increasing order? you are doing, and learn ways to become involved with the our faculty and staff. We have identified common problems the RCF, Alan worked at IBM Watson working off-site and have written up documentation for how to Department. Our website is a valuable resource for current resolve these issues. This includes how to remote access, avoid & Research Labs where he conducted in- . .Let E be the coefficients in the happenings and news, so we encourage you toformation visit us securityregularly research and con- Problemresolve triggered 5 securityn blocks, and much more. These guides ∞ xⁿ n at www. math.umass.edu sulted with various government and law expansion:are available on . secour newx+tan RCF x web = page E (look. ⁿ n =0for then! right-most tab on the menu bar of the math website!)” enforcement agencies as a subject matter Show that they satisfy E =E =1 and for n≥1 expert on active cases. At the RCF, Alan 0 1 On a more somber note,is responsiblewe mourn for thethe design,passing implementation, on 2 July and security of ... 2018 of our dear colleaguethe Richard department’s S. Ellis, IT infrastructure an internationally as well as managing the daily regarded probabilist, andsupport a good operations. friend to many of us on campus and in the community. It’s an immeasurable loss to Let A be the set of all subsets S of Rachel Aronow came to UMass in 2017 to pursue a Problem 6. n our Department. For manyMasters years degree Richard in Applied edited Mathematics. the annual During this time, she {1, 2, ..., n} such that S contains the size |S| of S. Let Newsletter and monthly News Briefs, and I — your current Bn be the set of all S in An which are minimal, i.e., editor — enjoyed working with him on both for much of the if S contains some subset T in An then T = S. Show past decade. As I re-drafted the letter soliciting briefs this that the number bn of elements of the set Bn is the 8 DEPARTMENT OF MATHEMATICS & STATISTICS th September, I realized it was based on Richard’s traditional n Fibonacci number Fn (here F1 = 1 = F2 and after text, passed down from him to me several years ago. Both that Fn = Fn−1 + Fn−2). this Newsletter and the News Briefs have become Department traditions, shaped by each of us who has taken on the role of Problem 7. Evaluate π/2 1 editor, but Richard’s influence looms large. He and I shared many common interests outside mathematics, particularly an intellectual curiosity about languages and literature, and both Send solutions, comments, or feedback via email of us have been deeply committed to carry on the tradition of to Professor Franz Pedit 2 ANDREA NAHMOD RECOGNITION ALUMNI INTERVIEW DEPARTMENT Andrea HEAD’S was selected for MESSAGE 2020-21 as one of two Conti Fel- Athena and Julianne Higgins are recent math majors from our I’d like to welcomelows you in theto ourUMass Newsletter Amherst College as the of newNatural Department Sciences. Head.department I officially who work started at Sun on Life 21 FinancialJanuary in Waltham, MA. 2018. It’s a true honor The – selectionand somewhat of the Conti daunting Fellows is based– to followon campus in nomthe- footstepsAthena is of a 2018Farshid graduate Hajir and, whoJulie is a 2020 graduate. Both now serves as Viceinations, Provost endorsed of Academic by the department Affairs and and dean did and a onfantastic external jobsisters in hisinterned 3 years at Sunas LifeHead. after I take their over respective junior years. a department that’sletters risen of support.tremendously These nominations in stature are since reviewed I came by ato facul UMass- Eric in Sommers 1987. We’ve interviewed made them some recently. exceptional hires tyand committee improved of previous our graduate Conti Fellows and whoundergraduate provide a recom programs.- Our graduates have gone on mendation for the selections. Conti Fellows receive release time ES: What are your current positions? to do outstandingfrom things. other We’re duties veryfor one proud year, in of order our toalumni. concentrate on the Athena: We are both student research project they have proposed, as well as a cash stipend. actuaries at Sun Life Financial. A particular area of growthThe citation is our reads: number “Andrea of Nahmod’s undergraduate research lies majors, at the which continually exceedsI’ve been expectations. here 2.5 years. More We areand in more of our incoming studentsinterface recognize of nonlinear the partial benefits differential of majoring equations in (PDE) math. and We have almost 1000 amajors rotational in 7 areas:program, Actuarial where weScience, Applied Math, Computing,nonlinear Fourier Pure andMath, harmonic Statistics, analysis, Teaching while bringing and an to Individual concentration.switch Mathematics roles every twois also years. an I essentialwas part of any 21st centurybear tools education, and ideas fromas over geometry, 15,000 analytic UMass number students theory, take our classes each year.most recently working in what and probability. References praised the superb quality of Nah- you could call Actuarial IT, doing Thanks to the hardmod’s work research; of our as onesearch stated committee, succinctly: “Professor our tenure Nahmod track is position in Math Biologyprogramming was filled in bySAS our (a topstatistical candidate: one of the most prominent and well-respected senior research- programming language). Assistant Professorers Brianin the fieldVan Kotenof Partial is Differentialan expert inEquations applied (PDEs).” probability This Athena and Higgins numerical analysis, performing computer simulations of molecular systems with applications in biology, chemistry and materials science.We We get also time had to astudy very for successful our Conti Fellowship will allow Nahmod to focus on studying the actuarial exams. I’ve passed 4 exams (P, FM, IFM, and SRM) year in hiring 8 newinvariance outstanding of the Gibbs Visiting measure Assistant and the almost Professors: sure existence Siddhant and AgrawalI’m now studying, Panagiota for my Birmpafifth exam., Noriyuki I took the Hamada FM prep , Kuan-Wen Lai, Jonathanof strong solutions Simone in its, Zahra statistical Sinaei ensemble, Zheni for the Utic periodic and de Jiayu- class Zhai at UMass,. Our but new I passed Marshall Exam StoneP while VAP,there by Laura studying Colmenarejo on Hernando, will joinfocusing us in Wick Spring ordered 2019. cubic NLS in 3D.” my own. Andrea’s work was also recognized by an invitation to give Julie: I’m working as a valuation actuary, calculating the Our Newsletter, andan AMS the Invitedon-line Address Faculty at the News Joint BriefsMathematics at www.math.umass.edu, Meetings in reserves that provide Sun Life an needs opportunity to cover all toclaims highlight and expenses. some of the outstanding workJanuary. of Herour talk faculty is entitled in pushing “Propagation the ofenvelope randomness of underknowledge Day-to-day in mathematics it’s a lot of SAS andprogramming statistics and each Excel year: Visual Assistant Basic the flow of nonlinear dispersive equations”. Professor Nestor Guillen spoke at the Austin workshop “Gerrymanderingtoo. I startedSteals my Elections: position in Learn mid-June, how so It’sall myDone work and has beenHow to remote. My team is based in Kansas City, so I would be doing a Stop It,” and was part of a panel on the topic including US Representative Jim McGovern this year; Associate Professor Paul lot of online meetings even without COVID. We use Zoom and Hacking was invited to lecture at the 2018 International Congress of Mathematicians;Workplace by Facebook Associate to stay connected. Professor Alexei Oblomkov was awarded a Simons Fellowship; Professors Markos Katsoulakis and Luc Rey-BelletI also get time received to study a formajor my actuarial Air Force exams. grant I passed to develop performance guarantees in predictive modeling; Professor Andrea NahmodP and FM was at UMass part of and a I’mfeature studying honoring for IFM womennow. I took in the the Notices of the AMS; and University Distinguished Professor Panos KevrekidisExam published P prep class 4 papers at UMass, in thebut I Nature studied for family FM on of my journals. own. Our Department hosted 3 conferences this past year: Associate ProfessorES: Tell Anna me moreLiu wasabout among your use the of organizersSAS and Excel of inthe your 32 nd New England Statistical Symposium bringing together nearly 250 statisticiansjobs. to discuss emerging issues in April 2018; Professor Andrea Nahmod helped organize Women in Partial Differential EquationsAthena: in A March lot of our 2018; older processesand Associate are in Excel, Professor with Excel Hongkun files Zhang co-organized Mathematical Physics Perspective of Billards and Dominoesall over the place, celebrating and we are the moving 70th morebirthdays things toof SAS Pavel since Bleher it and allows us to demonstrate more clearly that particular processes Leonid Bunimovich in September 2017. are doing the correct thing, which the auditors like. SAS is also faster. UMass Amherst undergraduates Jonah Chaban, Artem Vysogorets, andJulie: Jimmy It also goes Hwang the other worked way where as a team,we take led a SAS by processAssistant Professor Matthew Dobson, to produce the top-scoring project amongthat’s 7 competing built into a model teams and at then the take first the ideaever of Student it and build Competition an Using Modeling (SCUDEM) in Fall 2017. Three more SCUDEM teamsExcel led file by to Dobson prove that also it’s workingdid very correctly. well in Spring 2018, receiving meritorious mention and outstanding mention. Athena: That’s true. We have modeling software to project out Genus 2 surface of constant mean curvature in the 3-sphere 100 years. Say we want to manipulate one variable and see what We are very sad to(See have page lost 24 for an details) important member of our faculty, Richardhappens. S. EllisWe can, who apply passed the change away to in every July insurance 2018. Richard policy, joined but if we first want to test it, we’ll take the idea of what the the department in 1975, and also taught classes in Judaism and the Torahmodeling as an program adjunct is doingprofessor and apply of Judaicit to a single and policy Near using Eastern Studies. He was an internationally regarded expert in probability and large deviation theory, who also cared very much about the well-being of his students and colleagues, organizing sessions to relieve stress both inside and outside of the classroom. Richard will be truly missed. 2019-2020 Volume 35 9 We are also sorry to report the retirement of two important members of our faculty, Michael Lavine and Bill Meeks, in May 2018. Professor Lavine, a well-respected Bayesian statistician and a leader in our statistics group, had been a department member since 2008. Professor Meeks held the prestigious George David Birkhoff chair since joining the department in 1986; he is a world-renowned differential geometer and topologist, with a distinguished reputation in the area of minimal surfaces. The support of our alumni and friends is invaluable to us. We want to know how you are doing. Please send us your news, or stop in for a visit. – Nathaniel Whitaker DEPARTMENT OF MATHEMATICS & STATISTICS 2018 Volume 33 3 3 Excel and then do the same hundred-year projection to prove ES: You both studied abroad during your final semester. the modeling software is working correctly. It reminds me of Julie: Yes, I was in Ireland last spring, before being sent home in sensitivity analysis in differential equations. March because of the COVID outbreak. NEWAthena: CHALLENGEI spent my seventh and finalPROBLEMS semester in Switzerland. ES: What was your path toward pursuing actuarial science? MATHEMATICS & HereOutside is of a classselection time, I backpackedof some of throughout the more the challenging country by Athena: I came to UMass interested in Applied Math, maybe train and went on countless hikes. The Swiss cherish, celebrate, problems from the 2018 Jacob-Cohen-Killam prize STATISTICSsomething related to environmental science. and work hard to preserve their country’s ecology — I admired Julie: I began as a biochemistry major, planning to study exam.this during Three my time additional there. prize exam problems are NEWSLETTERpharmacy, and was a double major in math. But after talking to included in the Awards Dinner article on page 14... Athena, who loved the math department and was then pursuing ...... ES: Both of you were actively involved in AWM (Association the actuarial track, I decided to switch completely to math. for Women in Mathematics). Tell me about that. EDITED BY . Compute the volume of the 2018– Athena: We learned from each other and found our way to the ProblemJulie: I was involved 1 since my first year. I became the treasurer actuarial track together. We only overlapped at UMass for one dimensional simplex Richard S. Ellis Robert Kusner and then the president of AWM. year — it was a lot of fun to have that year together. Athena: I was treasurer2018 sophomore year when our AWM {(t1, ... , t2018 R t1 t2018 . chapter was founded. AWM was the best thing that happened ES: What research experiences did you have at UMass? ...... to me. I made some great friendships through AWM (my good DESIGNEDAthena: I did an BY REU (Research Experience for Undergraduates) friend, Shelby Cox,)∈ was the : 0 chapter’s ≤ ≤ first ··· ≤ president). ≤ 1}AWM is Given numbers a , a , a , a , suppose Brigetteat the Scripps McKenna Institute after sophomore year, using MATLAB Problemgreat at helping 2. building confidence. It1 was2 great3 to4 talk with to model the ocean current off the coast of San Diego. There agraduaten is defined students recursively about math. as was a camera that took tons of pictures per minute and the Julie: Yes, the graduate students are a bridge between the faculty code analyzed the photos to model the and athen = undergrads. (an−1 + a Theyn−2 + helpedan−3 + mea n−4decide)/4. what classes to take. IN COOPERATION WITHcurrent. Sometimes math can be isolating, so AWM helped me with Julie: I participated in the LEE- Showfinding that students the tosequence study with. {a Math} converges has a gender-imbalance, and SIPS program (through the College but the actuarial field is quite balancedn gender-wise. Q.Y. CHEN P. FLAHERTY O. GWILLIAM of Natural Sciences), working with calculate L = limn→∞ an...... P. HACKING J. HOROWITZ S. HROBAR Biostatistician Laura Balzar on an HIV/ ES: Rumor has it there is a third Higgins sister who is a UMass V. LYZINSKI I. MIRKOVIC AIDSA. study. MORALES I also attended weekly lab graduate? meetings with Nicholas Reich and his Problem 3. Consider a regular tetrahedron with F. PEDIT A. RAYMOND C. RUSSELL edgesJulie: Yes, of Ilength have a twin 1. What sister, who is the majored length in computer of the shortestscience Julianne Higgins team. For my project, I used R (statistical at UMass. She also works in insurance, for Liberty Mutual as a N. WANG N. WHITAKER R. YOUNG programming language) to do various simulation studies. Laura loopcomputer on itsprogrammer. surface whichWe never surrounds had a class together,two vertices? but we .. was an amazing mentor and teacher, and I am very grateful I would study together while taking the calculus classes. It was fun had this summer experience to open my eyes to the real-world ...... The Department of Mathematics and Statistics publishes to compare notes while she was taking CS 250 (Discrete Math applications of math/statistics. Problemfor CS) and I4. was How taking many Math 3003×3 (Introduction arrays are tothere Abstract such its annual newsletter for alumni and friends. You are thatThinking). (i) entries The courses include overlapped all the for digits a while, from before 1 diverging.through important, and we want toES: hear What from were you! you Pleasefavorite contact or most usimportant at courses at 9, and (ii) entries in every row and column are in [email protected] toUMass? share your news, let us know how increasingES: Any parting order? thoughts? you are doing, and learnJulie: ways Statistical to become Programming involved (STAT with 535) thewith Patrick Flaherty Athena: Insurance impacts everything. It touches on the Department. Our website— ais great a valuable course where resource we learned for Python current and how to apply it environment, which comes up in Property and Casualty to statistical questions. Also, Linear Regression (Stat 525) with happenings and news, so we encourage you to visit us regularly ProblemInsurance. Julie’s 5. . Letand myEn workbe the touches coefficients on public health in the issues Erin Conlon. We learned to use SAS, which as I mentioned is ∞ xⁿ n at www. math.umass.edu expansion:(like the Affordable .sec xCare+tan Act). x = As EElon . ⁿMusk n=0 recently n! said (on important for my current job. Twitter), we need some creative actuaries to figure out how to Athena: So many great courses. Math Modeling with Nate insureShow self-driving that they cars. Insurancesatisfy E is0 needed=E1 =1 for and so many for things.n≥1 On a more somber note,Whitaker. we mourn I loved thethe exploratory passing natureon 2 ofJuly the course and doing the group and individual projects. Also, Stat 525. I took it with ... 2018 of our dear colleague Richard S. Ellis, an internationally Daeyoung Kim and we also used SAS. He met with each group regarded probabilist, andseveral a good times friendduring the to semestermany ofto helpus onus with the project, which was great. campus and in the community. It’s an immeasurable loss to Problem 6. Let An be the set of all subsets S of our Department. For many years Richard edited the annual {1, 2, ..., n} such that S contains the size |S| of S. Let Newsletter and monthly News Briefs, and I — your current Bn be the set of all S in An which are minimal, i.e., editor — enjoyed working with him on both for much of the if S contains some subset T in An then T = S. Show past decade. As I re-drafted the letter soliciting briefs this that the number bn of elements of the set Bn is the 10 DEPARTMENT OF MATHEMATICS & STATISTICS th September, I realized it was based on Richard’s traditional n Fibonacci number Fn (here F1 = 1 = F2 and after text, passed down from him to me several years ago. Both that Fn = Fn−1 + Fn−2). this Newsletter and the News Briefs have become Department traditions, shaped by each of us who has taken on the role of Problem 7. Evaluate π/2 1 editor, but Richard’s influence looms large. He and I shared many common interests outside mathematics, particularly an intellectual curiosity about languages and literature, and both Send solutions, comments, or feedback via email of us have been deeply committed to carry on the tradition of to Professor Franz Pedit 2 HABEN MICHAEL INTERVIEW Continued DEPARTMENT MW: Obviously HEAD’S the pro bono MESSAGE work is interesting for readers, I’d like to welcomeso youdetails to of our any Newsletter specific cases/results as the new would Department be great to have. Head. I officially started on 21 January 2018. It’s a true honorHM: In – lawand school somewhat clinics Idaunting spent a lot –of to time follow representing in the footsteps of Farshid Hajir, who now serves as Viceprisoners, Provost in ofparole Academic hearings, Affairssuits over theirand conditions,did a fantastic etc. A job in his 3 years as Head. I take over a department that’slonger risen project tremendously involved the data in analysisstature that since went I into came the expertto UMass in 1987. We’ve made some exceptional hires reportand improved submitted to our the Connecticutgraduate and state undergraduate legislature when they programs. Our graduates have gone on to do outstandingwere things. considering We’re veryoverturning proud the of ourstate’s alumni. death penalty. The thrust of our argument was that the state’s prosecutors were choosing whether to charge the death penalty in an arbitrary and A particular area inconsistentof growth manner.is our numberSide-stepping of undergraduate the basic moral questions majors, which continually exceeds expectations. More and more of our incoming studentsabout the recognize death penalty, the ours benefits was a position of majoring that, if true, in math. We have almost 1000 majors in 7 areas: Actuarial Science, Applied Math, Computing,many could back Pure without Math, too Statistics, many misgivings. Teaching and an Individual concentration. Mathematics is also an essential part of any 21st century education, as over 15,000 UMass students take our classes each year. MW: How do you manage to keep doing it, with your other Thanks to the hardjob? work of our search committee, our tenure track position in Math Biology was filled by our top candidate: Assistant ProfessorHM: Brian Since movingVan Koten into statistics is an expert I mostly in assist applied with relatively probability and numerical analysis, performing computer small-stakes cases like landlord-tenant disputes, CORI seals, simulations of molecular systems with applications in biology, chemistryTetranoid, and materials a quadruply science. punctured We constant also had mean a verycurvature successful year in hiring 8 newetc. Asoutstanding far as time commitment Visiting Assistant goes, probably Professors: an average Siddhantof 2-3 sphere Agrawal in Euclidean, Panagiota 3-space (SeeBirmpa page 24, Noriyukifor details) Hamada, hours per week. But it’s different enough from statistics that it’s Kuan-Wen Lai, Jonathan Simone, Zahra Sinaei, Zheni Utic and Jiayu Zhai. Our new Marshall Stone VAP, Laura Colmenarejo a nice break. The last year and half I’ve been helping a friend, Hernando, will joinalso usa statistician, in Spring in 2019. a suit with his landlord. We talk about it for hours, and it’s like a break from work. I heard of a math Our Newsletter, andprofessor the on-lineat U. Toronto Faculty who Newsis also aBriefs lawyer atwho www.math.umass.edu, takes part in provide an opportunity to highlight some of the outstanding worklarge cases, of our but faculty that’s beyond in pushing me. the envelope of knowledge in mathematics and statistics each year: Assistant Professor Nestor Guillen spoke at the Austin workshop “Gerrymandering Steals Elections: Learn how It’s Done and How to Stop It,” and was partMW: Iof saw a panela book onby Leothe Katz:topic “Why including the law USis so Representative perverse”. Jim McGovern this year; Associate Professor Paul Hacking was invitedMy recollection to lecture is at that the it 2018is related International to social choice Congress paradoxes, of Mathematicians; Associate Professor Alexei Oblomkov was awarded a SimonsWhat Fellowship; is or should Professors be the relationshipMarkos Katsoulakis between law and and Luc Rey-Bellet received a major Air Force grant to develop mathematics, in your view? performance guarantees in predictive modeling; Professor Andrea Nahmod was part of a feature honoring women in the Notices of the AMS; and UniversityHM: I think Distinguishedfor the law, as with Professor the sciences Panos and many Kevrekidis other published 4 papers in the Nature family of journals. endeavors, math holds out the ideal of universally accepted Our Department truthshosted and 3 a conferences universally accepted this past method year: of establishing Associate those Professor Anna Liu was among the organizers of the 32nd New England Statisticaltruths. Symposium Can the law bringing get close together to that kind nearly of ideal? 250 I thinkstatisticians our Lawson’s to discuss genus emerging 2 minimal surface issues in in the April 3-sphere 2018; Professor (See page 24 for details) Andrea Nahmodlegal helped system organize accepts there Women will neverin Partial be consensus Differential on what Equationsis in March 2018; and Associate Professor Hongkun Zhang co-organizedtrue Mathematicalor right, and just Physicsfocuses on Perspective dispute resolution. of Billards You justand Dominoes celebrating the 70th birthdays of Pavel Bleher and Leonid Bunimovichagree in on September a way to obtain 2017. the truth, a proof system, so to speak, whether it be trial by fire, trial by jury, judicial finding, etc. It seems similar to the role that p-values play in some applications UMass Amherst undergraduatesof statistics. Maybe Jonahthe European Chaban legal, traditionArtem Vysogoretsgets closer to , and Jimmy Hwang worked as a team, led by Assistant Professor Matthewthe Dobsonmathematical, to produceideal. Of course the top-scoring if you aren’t usingproject a proof among 7 competing teams at the first ever Student Competition Using Modeling (SCUDEM)system as reliable in Fallas math’s, 2017. you Three will probably more SCUDEMwrongly assert teams led by Dobson also did very well in Spring 2018, receiving meritorioussomething mention as objectively and outstanding true, which may mention. be worse than what we’re doing. We are very sad to have lost an important member of our faculty, Richard S. Ellis, who passed away in July 2018. Richard joined the department in 1975, and also taught classes in Judaism and the Torah2-lobed as an equivariant adjunct constrainedprofessor Willmoreof Judaic torus and Near Eastern Studies. He was an internationally regarded expert in probability and large(See pagedeviation 24 for details) theory, who also cared very much about the well-being of his students and colleagues, organizing sessions to relieve stress both inside and outside of the classroom. Richard will be truly missed. 2019-2020 Volume 35 11 We are also sorry to report the retirement of two important members of our faculty, Michael Lavine and Bill Meeks, in May 2018. Professor Lavine, a well-respected Bayesian statistician and a leader in our statistics group, had been a department member since 2008. Professor Meeks held the prestigious George David Birkhoff chair since joining the department in 1986; he is a world-renowned differential geometer and topologist, with a distinguished reputation in the area of minimal surfaces. The support of our alumni and friends is invaluable to us. We want to know how you are doing. Please send us your news, or stop in for a visit. – Nathaniel Whitaker DEPARTMENT OF MATHEMATICS & STATISTICS 2018 Volume 33 3 3 INTERVIEW WITH GEORGE AVRUNIN, ON had that kind of place where faculty and graduate students mix, THE OCCASION OF HIS RETIREMENT FROM and we’re hopeful that the renovations now being planned will THE DEPARTMENT make that possible. NEWBB: I know CHALLENGE that your field is algebra PROBLEMS and representation theory, After 44 years at UMass, George but I was also aware in the ‘90s that if anybody had a question MATHEMATICSAvrunin & retired at the end of the Here is a selection of some of the more challenging about LaTeX or any software oriented question, you were spring term. On the occasion of this problems from the 2018 Jacob-Cohen-Killam prize STATISTICS always the go-to guy. How did that come about? milestone I had a chance to interview exam. Three additional prize exam problems are GA: I have always worked in other areas beyond mathematics. NEWSLETTERGeorge to get some perspective included in the Awards Dinner article on page 14... on his experiences as a teacher, In my senior year of college I wasn’t sure whether I wanted to researcher, and department head...... apply to graduate school in math or psychology. I was working EDITED BY George was born in Detroit and grew as a research assistant. Compute in what the we volume would now of thecall cognitive2018– Problempsychology. Back 1 then, as a math graduate student, you had up in the Detroit area. He received dimensional simplex Richard S. Ellis Robert Kusnerhis bachelor’s and doctoral degrees to take some courses outside of the department, so I went to from the University of Michigan. He came to our department the mathematical psychologist2018 Clyde Coombs, who taught {(t1, ... , t2018 R t1 t2018 . in 1976, and in addition to his research and teaching, he served a famous graduate course I had taken as an undergraduate...... Together we made up some independent study courses. These DESIGNEDfor eight years BYas associate department head, three years as )∈ : 0 ≤ ≤ ··· ≤ ≤ 1} head and two terms as acting head. He has also been an adjunct dealt with what are called single-peaked preference functions, Problemin which respondents 2. Given have numbers some ordering a1, a of2, choices.a3, a4, supposeIt turns Brigettefaculty memberMcKenna of the computer science department since 1992. a is defined recursively as — Brian Burrell outn that these situations are quite common for simple choices. [“With simple stimuli like amount of sugar in coffee or grade expectations in courses, the preference orders of individuals BB: What was your impression of UMass when you arrived? an = (an−1 + an−2 + an−3 + an−4)/4. can be represented by single-peaked functions of an underlying IN COOPERATIONGA: It was already oneWITH of the strongest institutions in the state, ordering. When stimuli are more complex, as in candidates but perception hadn’t caught up with that yet. There was the Show that the sequence {a } converges and for office or automobiles, there nis usually no natural ordering Q.Y. CHEN P.Zoo FLAHERTY Mass mentality. At theO. time, GWILLIAM the UMass graduate programs calculateunderlying theL = stimuli, limn→∞ and an .hence ...... the preference orders cannot were much smaller than they are now; it was very much an P. HACKING J. HOROWITZ S. HROBAR be single-peaked functions in one dimension.” Coombs & undergraduate institution. That has changed. We have a lot V. LYZINSKI I. MIRKOVIC A. MORALES Avrunin, 1977.] One of Coombs’s major research contributions more out-of-state students, and the university has continued to Problemhad to do with 3. developing Consider scaling a regular techniques tetrahedron for these things. with F. PEDIT A.get RAYMOND better. The students andC. their RUSSELL families in the state recognize edgesOne day of Coombs length came 1. Whatinto the isoffice the lengthand he drew of thesome shortest pictures N. WANG that now, and they treat us as a serious place. N. WHITAKER R. YOUNG looprelated on to itscomplex surface preference which functions surrounds in 2 dimensions,two vertices? but .. BB: Who else came in when you were hired? all he had were these pictures. So I turned the pictures into GA: Richard Ellis and Eduardo Cattani came in a few years .mathematics...... and extended it to n dimensions. We wrote two The Department of Mathematicsbefore, but H.K. andHsieh Statistics and a mathematical publishes physicist named Jay Problempapers that explained 4. How the many interplay 3×3 between arrays the are properties there such of its annual newsletter Rosenfor alumni were hired and in my friends. year. You are thatthe options (i) entries and the include properties all of the preferences. digits from So even 1 through when important, and we want toBB: hear As we from speak, you! they Please are tearing contact down us atWorcester Dining 9,I was and doing (ii) myentries research in everyin the cohomologyrow and column of groups, are I was in [email protected] toCommons. share your When news, I arrived let ushere know in the howearly ‘80s there was a increasingdoing this other order? kind of work. I came to UMass and did algebra, you are doing, and learncafeteria ways toon becomethe lower level.involved It was awith gathering the place for people but I maintained the contact with Coombs, and we eventually published a monograph on social conflict. Department. Our websitein theis adepartment. valuable Iresource bring this upfor because current I wanted to ask you how the university atmosphere has changed in your time here. BB: And computer science? happenings and news, so we encourage you to visit us regularly Problem 5. .Let En be the coefficients in the ∞ xⁿ n at www. math.umass.eduGA: When I got here we had that 16th floor area, and many of expansion:GA: That began .sec during x+tan a budgetary x = E crisis. ⁿ nwhen=0 theren! was talk the faculty had come from departments that had very active of layoffs of untenured faculty. I thought I’d better be thinking common rooms, places with a lot of informal interaction among aboutShow options, that so they I went satisfy to Jack E Wileden,0 =E1 =1 who and had for been n≥1 my On a more somber note,grad we students mourn and thefaculty. passing But we didn’ton 2 haveJuly that kind of thing undergraduate... roommate for a couple of years and had gotten a job in computer science at UMass [note: he is currently Associate 2018 of our dear colleaguehere. Richard My first S. coupleEllis, anof years internationally a bunch of us kept coming up with ideas to make that into a gathering place. We would have Dean of Student Affairs]. I said I wanted to sit in on a few classes, regarded probabilist, andnewspaper a good subscriptions friend to deliveredmany of there, us onand we would have and Jack suggested data structures, the compiler course, and a campus and in the community.cookies every It’s afternoon, an immeasurable and the same loss three to of us would show Problemcouple of others. 6. LetThen A nhe be came the to set me ofwith all a subsetsproblem. SHe of was our Department. For manyup every years day Richard for the cookies. edited I think the annualthe department has never {1,trying 2, ...,to n}read such a paper that in S distributed contains systems,the size written |S| of byS. Leta Newsletter and monthly News Briefs, and I — your current Bn be the set of all S in An which are minimal, i.e., editor — enjoyed working with him on both for much of the if S contains some subset T in An then T = S. Show past decade. As I re-drafted the letter soliciting briefs this that the number bn of elements of the set Bn is the 12 DEPARTMENT OF MATHEMATICS & STATISTICS th September, I realized it was based on Richard’s traditional n Fibonacci number Fn (here F1 = 1 = F2 and after text, passed down from him to me several years ago. Both that Fn = Fn−1 + Fn−2). this Newsletter and the News Briefs have become Department traditions, shaped by each of us who has taken on the role of Problem 7. Evaluate π/2 1 editor, but Richard’s influence looms large. He and I shared many common interests outside mathematics, particularly an intellectual curiosity about languages and literature, and both Send solutions, comments, or feedback via email of us have been deeply committed to carry on the tradition of to Professor Franz Pedit 2 famous guy using some pretty sophisticated math in set theory using it a year later. She went on to become the computer science and logic. So we read this paper together, and Jack and I said, department chair at Michigan State. DEPARTMENT HEAD’S MESSAGE “We can do better than this.” This is how I got into computer BB: What are your plans now that you are stepping down? I’d like to welcomescience. you toBy theour way, Newsletter Robin Milner, as the guy new who Department wrote that paper, Head. I officially started on 21 January GA: I’m not stepping down completely just yet. I’m going to 2018. It’s a true honorwon the – Turing and somewhat Award, the highest daunting award – in to computer follow science,in the footsteps of Farshid Hajir, who teach two courses in the fall and not teach in the spring. My now serves as Vicepartly Provost for the of stuff Academic we thought Affairs we could anddo better did than.a fantastic job in his 3 years as Head. I take over a department that’s risen tremendously in stature since I came to UMassrecent in research1987. We’ve has been made related some to the idea of looking at systems BB: At that time computer science was in the low-rise. When where the people are really part of the system, not just end exceptional hires didand it becameimproved a serious our presencegraduate on and campus? undergraduate programs.users. So Our we talkgraduates about things have like gone elections, on voting systems, to do outstandingGA: things. It was We’re already very a department proud of by our the alumni.time I got here. One and medical care, in which users interact with medical devices. of the reasons it was successful is that of the top 25 computer We’ve been treating these as concurrent or distributed systems, A particular area scienceof growth departments is our numberfrom the of‘80s undergraduate onward, there were majors, two whichand modeling continually them using exceeds a programming expectations. language More that focuses and more of our incoming studentsdepartments recognize that had the a benefits reputation ofas majoringbeing very in collegial. math. onWe thehave kinds almost of interactions 1000 majors and inchoices 7 areas: that occurActuarial in these Science, Applied Math, Computing,These were PureUMass Math, and Washington. Statistics, If Teaching you asked andanyone an inIndividual situations. concentration. This work has been Mathematics supported by isthe also NSF an and essential the part of any 21st centuryacademic education, computer science as over about 15,000 where UMass people studentsworked well take NIH, our andclasses we’ve each just receivedyear. a four-year renewal of our NIH together, they all said the same. The UMass computer science grant applying this to computer-aided surgery. We’re using department shared resources very well, and they built up a models to analyze and identify problems that could come up Thanks to the hardstrong work department of our quickly.search Whencommittee, I first interactedour tenure with track them positionwhen things in don’tMath synchronize Biology properly.was filled (I now by know our atop lot aboutcandidate: Assistant Professorthey Brian had a decentVan Koten graduate is program. an expert They in appliedwere open probabilityto having the and kinds numerical of things that analysis, can go wrong performing in cardiac computer surgery.) Also simulations of molecularme work with systems their people. with Oneapplications of the things in I am biology, really grateful chemistry we are and measuring materials proxies science. for the We cognitive also had load aon very the leaders successful year in hiring 8 newfor is outstanding how the computer Visiting science Assistant department Professors: has allowed meSiddhant to of the Agrawal surgical ,teams, Panagiota and trying Birmpa to identify, Noriyuki situations Hamada where , Kuan-Wen Lai, Jonathanbe a computer Simone scientist,, Zahra but also, Sinaei and more, Zheni importantly, Utic theand way Jiayu they Zhai are .more Our likely new to Marshall make mistakes Stone because VAP, Laurathe cognitive Colmenarejo Hernando, will jointhe mathus in department Spring 2019. has allowed me to do these other things. load is high. In situations where some part of the procedure is They didn’t say, “We hired you to do group theory, so you should especially complicated, we hope to provide ways to reduce the be doing group theory.” And it wasn’t just the math department. load through a smart checklist which is generated from our Our Newsletter, andI have the the on-line letter that Faculty the dean News [Fred Byron] Briefs wrote at www.math.umass.edu, on my tenure models for provide human processes. an opportunity So I will beto workinghighlight on somethat, I of the outstanding workcase, and of ourhe said faculty here is in someone pushing who the is making envelope contributions of knowledge hope, forin mathematicsfour more years, and in statistics retirement each will do year: some Assistant other Professor Nestor inGuillen three different spoke areas, at the and Austin we should workshop foster that. “GerrymanderingSo UMass was fun things Steals I have Elections: had less time Learn to do. how It’s Done and How to Stop It,” and was parta place of that a panellet me do on that, the and topic I’m notincluding sure there US are manyRepresentative other Jim McGovern this year; Associate Professor Paul Hacking was invitedplaces to that lecture would haveat the let 2018me do Internationalit the same way. Congress of Mathematicians;AWM CHAPTER Associate UPDATE! Professor Alexei Oblomkov was BB: So you had your hand in the new technology. awarded a Simons Fellowship; Professors Markos Katsoulakis and Luc Rey-BelletOur student received chapter of a majorthe Association Air Force for grantWomen to indevelop performance guaranteesGA: I set inup predictive the RCF and modeling; served for severalProfessor years Andreaas its first Nahmod Mathematics was (AWM) part of continues a feature to buildhonoring and grow women a community in the Notices of the AMS; and Universitydirector. In fact, Distinguished I am the person Professor responsible Panos for bringing Kevrekidis TeX of published gender minority 4 papers mathematics in the Natureand statistics family undergraduate of journals. to UMass. Jack and I had a grad student, Laura Dillon, who students, graduate students, faculty, and staff members. The Our Department washosted working 3 conferences on a thesis that this had pastlots of year: mathematical Associate notation. Professor AWM Anna chapter Liu is continuing was among to run the in our organizers new remote of format the 32by nd New England StatisticalAt Symposium that time, to print bringing it we used together something nearly called 250 Runoff. statisticians You hosting to discuss discussions emerging through issuesSlack and in events April through 2018; Zoom. Professor printed on printers with daisy wheels, and you had to swap the Andrea Nahmod helped organize Women in Partial Differential Equations Some in March of our big 2018; hits from and last Associate year to this Professor year are: Hongkun daisy wheels, and it was terrible. In 1982 the computer science th Zhang co-organizeddepartment Mathematical bought a laser Physics printer Perspective for $25,000. With of Billardsa laser printer and Dominoes• Undergraduate celebrating Homework the 70Night birthdays of Pavel Bleher and Leonid Bunimovichyou couldin September run TeX. I had 2017. read about it in the AMS Bulletin, and • The AWM Summer Book Club I said, “We should get this.” I was particularly interested in this • AWM Undergrad + Grad Student Mentoring Lunches UMass Amherst undergraduatesbecause my father was Jonah a printer. Chaban He was, Arteminvolved Vysogoretsin some early , and• AWMJimmy Grad Hwang Student worked + Post Doc as Mentoring a team, ledLunches by Assistant Professor Matthewand Dobson not very successful, to produce attempts the totop-scoring use electronic project typesetting, among • 7 AWMcompeting Departmental teams Coffee at the firstHours ever Student Competition Using Modeling (SCUDEM)but he got me ininterested Fall 2017. in typography Three frommore SCUDEMearly on. There teams • ledThe by AWM Dobson Fall ‘20 also Hidden did veryFigures well Book in Club Spring 2018, receiving meritoriouswas a mentionUMass grad and student outstanding who was spending mention. the summer at Stanford, and after I requested it, he brought back a tape with We are hoping to plan a remote career panel for the Spring a pre-release version of TeX82, which became the widespread semester, so if you are a UMass alum who would be interested We are very sad toTeX. have It took lost some an importantwork for Computer member Science of ourto compile faculty, it and Richard in sharing S. Ellis a bit, whoabout passedyour career away with in us, July please 2018. reach Richard out to joined the department inget 1975, it to work and on also their taught laser printer. classes Laura in Dillon Judaism wrote and her thesis the Torah [email protected]. as an adjunct professor of Judaic and Near Eastern Studies. He was an internationally regarded expert in probability and large deviation theory, who also cared very much about the well-being of his students and colleagues, organizing sessions to relieve stress both inside and outside of the classroom. Richard will be truly missed. 2019-2020 Volume 35 13 We are also sorry to report the retirement of two important members of our faculty, Michael Lavine and Bill Meeks, in May 2018. Professor Lavine, a well-respected Bayesian statistician and a leader in our statistics group, had been a department member since 2008. Professor Meeks held the prestigious George David Birkhoff chair since joining the department in 1986; he is a world-renowned differential geometer and topologist, with a distinguished reputation in the area of minimal surfaces. The support of our alumni and friends is invaluable to us. We want to know how you are doing. Please send us your news, or stop in for a visit. – Nathaniel Whitaker DEPARTMENT OF MATHEMATICS & STATISTICS 2018 Volume 33 3 3 IN MEMORIAM I have one anecdote I can share, although there are many happy memories I have of him. I remember when he was giving In order to commemorate former members of the department, away some math books after his retirement. He had some that Tom Braden has created an “In Memoriam” page at https:// NEWhe had preselected CHALLENGE to give to certain PROBLEMS people and then others MATHEMATICSwww.math.umass.edu/in-memoriam. & Please let us know if you where one could select anything one wanted. I saw that the can supply further details including new names for the list. Here2nd collection is a selection contained of asome copy of “Linearthe more Lie challengingGroups” by STATISTICS problemsFreudenthal fromand de the Vries. 2018 It’s hardJacob-Cohen-Killam to describe this book prizebut RIP JIM HUMPHREYS exam.it’s something Three like additional if Lewis Carroll prize had examdecided problems to write a book are NEWSLETTERThe department was saddened by the untimely death of Emeritus includedabout Lie groups in the under Awards the influence Dinner ofarticle PCP. it’son apage personal 14. .. Professor James (Jim) Humphreys in late August. Department favorite. I quickly snatched it up, and Jim’s expression was ...... Head Nate Whitaker informed us: inscrutable. I think I must have failed some kind of test that day EDITED BY :) — Paul Gunnells I am very sorry to say that our former colleague Jim Problem 1. Compute the volume of the 2018– dimensional simplex Richard S. EllisHumphreys Robertpassed early Kusner yesterday morning. He was a I am very saddened by the news of Jim Humphreys’ death. very important part of our department from 1974 until his {( t ,For ... ,more t thanR 302018 years he wast one of thet most influential. and1 best known2018 members of our Department.1 In2018 fact, a common retirement in 2003. He was a highly respected Mathematician in ...... Representation Theory, a mentor to many of our younger faculty response when somebody found out I was from UMass was to DESIGNED BY )∈ : 0 ≤ ≤ ··· ≤ ≤ 1} and a great departmental citizen. He published a classic textbook ask if that’s where Jim was. His research and his books on Lie Problem 2. Given numbers a , a , a , a , suppose Brigettein 1974, McKenna “Introduction to Lie Algebras and Representation Theory brought him a well-deserved worldwide1 2 3recognition.4 Theory” with a 7th edition in a n isAs defined Paul mentions, recursively Jim was ascentral to the development of 1997. the graduate program, serving as GPD for many years and Many colleagues in the attractingan = (manyan−1 +students an−2 + who an−3 knew + an−4 of )/4.him by his celebrated IN COOPERATIONdepartment and WITHelsewhere book on Lie Algebras. sent heartfelt emails, which Show Jim that was verythe generoussequence of his {a time} converges and was, as Nateand says, an exemplary citizen who believed stronglyn that a Department was Q.Y. CHEN P.have FLAHERTY been collated below.O. We GWILLIAM calculate L = lim a ...... hope that a more permanent more than the sum ofn→∞ its members. n P. HACKING J. HOROWITZ S. HROBAR and fitting memorial will be I always admired Jim’s appreciation of beautiful V. LYZINSKI I. MIRKOVIC A. MORALES mathematics as well as his commitment to human rights causes. possible when life returns to Problem 3. Consider a regular tetrahedron with F. PEDIT A.normal. RAYMOND A short obituary canC. be RUSSELL I will miss him. — Eduardo Cattani found here: https://www.legacy. edges of length 1. What is the length of the shortest N. WANG N. WHITAKER R. YOUNG Very sad news. Jim was an amazing colleague and knew an com/obituaries/erietimesnews/ loop on its surface which surrounds two vertices? .. infinite amount of mathematics which he willingly shared with obituary.aspx?pid=196925399 .us...... My personal favorites were the UMass-Northampton bus The Department of MathematicsReminiscences and Statistics publishes Problemrides Jim. I probably 4. How learnt many more 3×3 Representation arrays are theory there from such When I first joined the department there were limited its annual newsletter for alumni and friends. You are thatthese (i)rides entries than from include graduate all studies. the digits He will from be missed 1 through by all activities in number theory and I didn’t have a lot of people to of us. RIP. — Alexei Oblomkov important, and we want totalk hear to. Besides from you!David Please Hayes, contactJim and Peterus at Norman (who is 9, and (ii) entries in every row and column are in [email protected] toalive share and yourdoing verynews, well) let were us veryknow helpful how to me and offered increasing Jim came order? to UMass a few years before I did; he was the one you are doing, and learnmany ways useful to becomeadvice on mathematicsinvolved with and departmental the affairs. I whose interests were closest to mine then and was a big influence Department. Our websitereally is appreciatea valuable that. resource for current on me, too. In his department service, especially as GPD, as well as happenings and news, so we encourageThe thesis of youmy firstto visit student us regularly(John Cullinan) makes heavy Problem 5. .Let En be the coefficients in the his editing, reviewing, and general ∞ guidancexⁿ aboutn things, I’ve at www. math.umass.eduuse of group theory and representation theory; Jim stepped in expansion: .sec x+tan x = E . ⁿ n=0 n! and offered helps at critical junctures. And from Jim I inherited always thought of him as one of the fairest and most honest people I’ve known. — George Avrunin his collection of Glenn Gould on LPs. In his memory I will play Show that they satisfy E0 =E1 =1 and for n≥1 On a more somber note,the we Goldberg mourn Variations the passing now. —Siman on 2Wong July ...I’m very sorry to hear about Jim’s passing. He was extremely 2018 of our dear colleague RichardJim was always S. Ellis, a big an figure internationally in the department and was very kind to me when I first arrived at UMass (and many times regarded probabilist, andinfluential a good to friendme. I always to many really liked of ushim on and looked forward thereafter). He put real effort into making me feel welcome in campus and in the community.to seeing him. It’s alsoan myimmeasurable understanding isloss that to he was a key player the department, andLet I Awill be always the be set grateful of all to subsets him for that. S of Problem— Tom Braden 6. n our Department. For manyin getting years ourRichard graduate edited program the goingannual (maybe others can confirm). RIP. {1, 2, ..., n} such that S contains the size |S| of S. Let Newsletter and monthly News Briefs, and I — your current Bn be the set of all S in An which are minimal, i.e., editor — enjoyed working with him on both for much of the if S contains some subset T in An then T = S. Show past decade. As I re-drafted the letter soliciting briefs this that the number bn of elements of the set Bn is the 14 DEPARTMENT OF MATHEMATICS & STATISTICS th September, I realized it was based on Richard’s traditional n Fibonacci number Fn (here F1 = 1 = F2 and after text, passed down from him to me several years ago. Both that Fn = Fn−1 + Fn−2). this Newsletter and the News Briefs have become Department traditions, shaped by each of us who has taken on the role of Problem 7. Evaluate π/2 1 editor, but Richard’s influence looms large. He and I shared many common interests outside mathematics, particularly an intellectual curiosity about languages and literature, and both Send solutions, comments, or feedback via email of us have been deeply committed to carry on the tradition of to Professor Franz Pedit 2 Jim was one of the foundational authors of present day when I would visit Northampton. We would catch up on family, DEPARTMENTmodular representationHEAD’S theory. MESSAGE He was widely appreciated in local politics, and music (we had a shared love of classical music mathematics. For instance a paper of Bernstein, Gelfand and and Bruce Springsteen). He usually gifted me a book or two I’d like to welcomeGelfand, you to which our Newsletterhas become oneas the of organizingnew Department principles Head.in from I officiallyhis vast collection started when on I would21 January visit, and I will cherish 2018. It’s a true honorrepresentation – and theory,somewhat starts dauntingwith the explanation – to follow that theyin the are footstepsthem always. of Farshid — John Cullinan, Hajir, Associatewho Professor and Chair of now serves as Viceapplying Provost Jim’s of work Academic in a simpler Affairs setting. and did a fantastic jobMathematics in his 3 years Bard Collegeas Head. I take over a department that’s risenJim and tremendously I had offices nextin statureto each other since and I camemany occasions to UMass in 1987. We’ve made some exceptional hires toand talk. improved In time his our student graduate Cornellius and Pillen undergraduate married my first programs. I would Our graduateswish to emphasize have gone the onhuge contribution of to do outstandingstudent things. Elena We’re Galaktionova. very proud They of ourhad aalumni. long happy marriage James Humphreys to the professional mathematical education with two great kids. worldwide in the area of Lie algebras, algebraic groups, finite A particular area of growthBefore UMass is our Inumber thought ofthat undergraduate Jim’s field, the majors,modular whichgroups continuallyof Lie type and exceeds their representations. expectations. His Morebook “Linear and more of representation theory, was a jungle of random coincidences and algebraic groups” appeared in Russian under my translation in our incoming studentsthat I would recognize never touch the benefitsit. Through of Jim’s majoring teachings in I learnedmath. 1975We have and influencedalmost 1000 a lot tomajors algebraic in research7 areas: in Actuarialthe USSR. Science,His Applied Math, Computing,of hidden beauties Pure andMath, spine Statistics, of this new Teaching world — and many an of Individual last book “Modularconcentration. representations Mathematics of finite groups is also of anLie type”essential st part of any 21 centurywhich have education, originally asbeen over established 15,000 by UMass Humphreys students himself. take (2006) our classes is a real pieceeach of year. art, and accumulates enormous research Consequently, this became one of two principal fields where I material developed in the previous 50 years. These and his other Thanks to the hardwas successfulwork of ourin mathematics. search committee, The key factor our tenurein this wastrack my positionbooks will in serve Math for longBiology as an importantwas filled source by ofour information top candidate: Assistant Professorstudent Brian Dmitriy Van RumyninKoten is who an wasexpert really in a jointapplied student probability of Jim in theand area. numerical His own research analysis, publications performing concerned computer important simulations of molecularand me. When systems I was awaywith Jim applications taught him the in classical biology, modular chemistry problems and andmaterials were very science. encouraging We foralso solving had harda very problems. successful year in hiring 8 newrepresentation outstanding and presented Visiting him Assistant with a problem Professors: that eventually Siddhant In my Agrawal view James, Panagiota Humphreys Birmpa was a very, Noriyuki significant Hamadafigure in , had a radical geometric solution and resulted in a thesis paper my part of the mathematical world. Kuan-Wen Lai, Jonathanin Annals of Simone Mathematics., Zahra Methods Sinaei of modular, Zheni representation Utic and Jiayu ZhaiI never. Our met newJames Marshall personally Stonebut was VAP, in contact Laura on manyColmenarejo Hernando, will jointheory us havein Spring in time 2019.percolated in many fields of mathematics occasions since 1975. He was always very willing to help and and were influential in physics. share his knowledge with me. I feel his death as a personal loss. Our Newsletter, and Mythe long on-line term Facultystudy of physics News ofBriefs Quantum at www.math.umass.edu, Field Theory — Alexandre provide Zalesski, an Emeritus opportunity Professor, to highlightUniversity ofsome East of the outstanding workhas colored of our much faculty of my in view pushing on mathematics the envelope and the ofworld. knowledge It Anglia, in UK mathematics and statistics each year: Assistant Professor Nestor startedGuillen when spoke Jim gifted at the me Austin 1500 pages workshop books on the“Gerrymandering subject, the Steals Elections: Learn how It’s Done and How to Stop It,” and was partjoint workof a ofpanel Deligne, on Witten,the topic and includingothers. US Representative Jim McGovern this year; Associate Professor Paul I have heard a gossip that Jim said that, getting my tenure Hacking was invited to lecture at the 2018 International Congress of Mathematicians; Associate Professor Alexei Oblomkov was through, was the hardest work he has ever done. I imagine that awarded a Simonsit mayFellowship; have taken Professors more than one Markos person’s effort,Katsoulakis but otherwise and it Luc Rey-Bellet received a major Air Force grant to develop performance guaranteesis completely in predictivein keeping with modeling; my image ofProfessor Jim. For years Andrea he was Nahmod was part of a feature honoring women in the Notices of the AMS; and Universityorganizing the Distinguished representation theory Professor seminar Panos and used Kevrekidis it to take published 4 papers in the Nature family of journals. care of many less known mathematicians, with huge emphasis Our Department onhosted people 3rather conferences than on fame. this For past me year:it was important Associate to have Professor Anna Liu was among the organizers of the 32nd New England Statisticalsomeone Symposium close that bringing I could adore together as a human nearly being. 250 statisticians to discuss emerging issues in April 2018; Professor Andrea Nahmod helpedThese organize are just a few Women aspects inof Partialmy relation Differential with Jim and Equationsmy in March 2018; and Associate Professor Hongkun gratitude to him. Many I may never be able to express. — Ivan th Zhang co-organizedMirkovic Mathematical Physics Perspective of Billards and Dominoes celebrating the 70 birthdays of Pavel Bleher and Leonid Bunimovich in September 2017. I was very sad to learn of Jim’s passing. I read his SL(2,p) UMass Amherst undergraduatespaper as an undergraduate Jonah and Chaban he was ,the Artem main reasonVysogorets I came , and Jimmy Hwang worked as a team, led by Assistant to UMass to begin my graduate studies in 1999. I took four Professor Matthew Dobson, to produce the top-scoring project among 7 competing teams at the first ever Student Competition or five regular classes with him and an independent study in Using Modeling (SCUDEM)modular representation in Fall 2017. theory. Three He encouraged more SCUDEM me to attend teams led by Dobson also did very well in Spring 2018, receiving meritoriousthe Representation mention and Theory outstanding seminar in mention.addition to the Number Theory and helped me immensely with my dissertation. After We are very sad tofinishing have lost graduate an important school we keptmember in touch of andour he faculty, was always Richard S. Ellis, who passed away in July 2018. Richard joined the department inextremely 1975, and helpful also whenever taught I hadclasses mathematical in Judaism questions. and the Torah as an adjunct professor of Judaic and Near Eastern Studies. He was an internationallyOutside of mathematics, regarded I will expert miss our in dinnersprobability together and largeLozenge deviation tiling contributed theory, by whoAlejandro also Morales cared very much about the well-being of his students and colleagues, organizing sessions to relieve stress both inside and outside of the classroom. Richard will be truly missed. 2019-2020 Volume 35 15 We are also sorry to report the retirement of two important members of our faculty, Michael Lavine and Bill Meeks, in May 2018. Professor Lavine, a well-respected Bayesian statistician and a leader in our statistics group, had been a department member since 2008. Professor Meeks held the prestigious George David Birkhoff chair since joining the department in 1986; he is a world-renowned differential geometer and topologist, with a distinguished reputation in the area of minimal surfaces. The support of our alumni and friends is invaluable to us. We want to know how you are doing. Please send us your news, or stop in for a visit. – Nathaniel Whitaker DEPARTMENT OF MATHEMATICS & STATISTICS 2018 Volume 33 3 3 DEPARTMENTAL EFFORTS TO PROMOTE People from many different roles in the department INCLUSIVITY started meeting biweekly this summer to discuss texts on antiracist teaching. The group first read “Teaching Across This topic has become much more urgent nationally given the NEWCultural Strengths”CHALLENGE by Alicia Feledina PROBLEMS Chávez and Susan MATHEMATICSevents of last summer. Our College & of Natural Sciences has Diana Longerbeam, which describes different cultural learning been strong on this issue (see https://www.cns.umass.edu/ Hereframeworks, is a selection and the need of for some instructors of the to more rely on challengingall of STATISTICSdiversity-equity-inclusion). — Ed problemsthem so as not from to underserve the 2018 learners Jacob-Cohen-Killam who grew up in a prize The Department of Mathematics and Statistics’ Climate exam.particular Three framework. additional The group prize then exammoved onproblems to “Political are NEWSLETTERCommittee is dedicated to understanding and improving includedConocimiento in forthe Teaching Awards Mathematics Dinner article and Rehumanizing on page 14... the professional climate of our department. The committee ...... Mathematics” where Rochelle Gutiérrez challenges the includes representatives from the faculty, staff, graduate idea that learning and teaching mathematics is universal EDITEDstudent, and BY undergraduate student populations, and is Problemand culture-free. 1. TheCompute pièce de therésistance volume was “Teaching of the 2018– to working to systematically review and improve the experiences dimensionalTransgress” by Bell simplex Hooks in which education is presented as Richard S. Ellisof all these groups. Robert Kusner a practice of freedom, and the importance of creating learning The 2019-2020 Climate Committee conducted an 2018 {(communitiest1, ... , t2018 withinR our classroomst1 is emphasized.t2018 The . extensive survey of the experiences of our undergraduate ...... group is planning to continue meeting and further educate DESIGNEDstudents, with almost BY 400 respondents. We also held a pre- themselves on antiracist)∈ teaching. : 0 ≤ — ≤ Annie ··· ≤ Raymond ≤ 1} COVID social lunch with faculty and undergraduate Math Problem 2. Given numbers a , a , a , a , suppose Brigettemajors atMcKenna a dining hall, and worked to get more information DEPARTMENTAL SPACE 1 2 3 4 for prospective majors on the departmental website. The an is defined recursively as graduate student group is establishing an extensive graduate The department is nearing the end of the planning phase of a mentoring structure. The climate committee has also projectan to= renovate(an−1 + andan−2 expand + an−3 the + department’s an−4)/4. physical space. IN COOPERATIONfinancially supported WITH pre-talks before seminars to make them The plan includes acquiring 2 new wings of Lederle tower, former more accessible to all department members, meals for graduate Showlaboratory that space the on sequence the 15th and {a 16th} converges floors, to theand left as you exit the elevators. This space will nallow for a nicer undergraduate Q.Y. CHEN P.students FLAHERTY with visitors, and theO. purchaseGWILLIAM of books for graduate calculate L = lim a ...... students for the antiracist teaching reading group. The climate advising and lounge space,n→∞ 3n new sizeable meeting rooms, and 24 P. HACKING J. HOROWITZ S. HROBAR committee has also worked to streamline the shared use of new offices for faculty, staff, and graduate students. The 15th floor V. LYZINSKI I. MIRKOVIC A. MORALES will also include 2 discussion nooks to encourage spontaneous conference rooms. The climate and teaching committees also Problem 3. Consider a regular tetrahedron with F. PEDIT A.co-hosted RAYMOND a training sessionC. on intersectionalityRUSSELL led by the conversations. The project also includes renovation of the 16th edgesfloor colloquium of length space, 1. What including is the substantial length renovation of the shortest of the N. WANG N.UMass WHITAKER Stonewall Center. — KristaR. YOUNG Gile loopkitchenette on its and surface the section which to the surrounds right of the colloquium two vertices? room .. Department members were moved by the killing of as a common room. This renovation is needed to support the George Floyd and following events this summer to examine . .recent...... growth necessary to support all of our students. The the role of racism, and therefore antiracism, in our professional The Department of Mathematics and Statistics publishes Problemdesign has prioritized 4. How making many space 3×3 forarrays everyone, are therewhile alsosuch work. Department members have been active in dialogues in its annual newsletter for alumni and friends. You are creating more opportunities for community and connection our local and professional communities, as well as on campus that (i) entries include all the digits from 1 through within the department. Construction was scheduled to begin important, and we want toand hear in the from department. you! Please There contactis now a faculty-grad us at student 9, and (ii) entries in every row and column are in this academic year, but will be delayed due to the pandemic and [email protected] toreading share group your on news, antiracist let teachingus know and howa grad-student led increasing order? its budget and logistical impacts. — Krista Gile you are doing, and learnreading ways groupto become of the book involved Hidden Figures with . theThere is also a Department. Our websiteSlack is channela valuable where resource department for members current can share actions M.S. OPTION IN STATISTICS IN THE happenings and news, so orwe insights, encourage and a workingyou to visitgroup us of regularlypassionate volunteers Problem 5. .Let En be the coefficients in the BOSTON AREA ∞ xⁿ n at www. math.umass.eduinterested in anti racist action and change. This group is expansion: .sec x+tan x = E . ⁿ n=0 n! planning many additional projects to foster antiracism in our TheShow M.S. option that inthey Statistics satisfy at the E =NewtonE =1 Mountand forIda campusn≥1 department. We are learning about barriers to success for our of the University of Massachusetts0 Amherst1 began its second On a more somber note,Black we students mourn and the students passing from otheron 2 under-represented July year... in Fall 2020, under the direction of Associate Professor 2018 of our dear colleaguegroups Richard and working S. Ellis, to directan internationally recourses to reduce these Erin Conlon. This program is an evening program. There are barriers, including allocation of departmental resources and regarded probabilist, and a good friend to many of us on eleven graduate courses being offered during the 2020 - 2021 pursuing external funding sources. We are also developing a academic year, including Mathematical Statistics I and II, campus and in the community. It’s an immeasurable loss to long-term strategic plan for antiracism in our department. ProblemStatistical Computing, 6. Let A Statisticaln be the Methods set of forall Datasubsets Science, S of and our Department. For many — Krista years Gile Richard edited the annual {1,Data 2, Visualization, ..., n} such amongthat S others.contains Applications the size are |S |currently of S. Let Newsletter and monthly News Briefs, and I — your current Bn be the set of all S in An which are minimal, i.e., editor — enjoyed working with him on both for much of the if S contains some subset T in An then T = S. Show past decade. As I re-drafted the letter soliciting briefs this that the number bn of elements of the set Bn is the 16 DEPARTMENT OF MATHEMATICS & STATISTICS th September, I realized it was based on Richard’s traditional n Fibonacci number Fn (here F1 = 1 = F2 and after text, passed down from him to me several years ago. Both that Fn = Fn−1 + Fn−2). this Newsletter and the News Briefs have become Department traditions, shaped by each of us who has taken on the role of Problem 7. Evaluate π/2 1 editor, but Richard’s influence looms large. He and I shared many common interests outside mathematics, particularly an intellectual curiosity about languages and literature, and both Send solutions, comments, or feedback via email of us have been deeply committed to carry on the tradition of to Professor Franz Pedit 2 being accepted for the Fall 2021 class. More information on the than 100 virtual attendees. There were 27 contributed talks and DEPARTMENTprogram isHEAD’S available at https://people.math.umass.edu/~conlon/ MESSAGE 69 contributed posters including presentations by VAP Laura statmtida/ —Erin Conlon Colmenarejo and VAP Theo Douvropoulos. The best student I’d like to welcome you to our Newsletter as the new Department Head.presentation I officially prize started of the conferenceon 21 January was supported by our 2018. It’s a true honorUNDERGRADUATE – and somewhat RESEARCHdaunting – to follow in the footstepsdepartment. of FarshidThe virtual Hajir meeting, who included social activities like a now serves as Vice Provost of Academic Affairs and did a fantastic jobpuzzle in his hunt, 3 years a virtual as excursionHead. I takeusing theover website Geoguessr, a There were 10 REU students for summer 2020: six were supported a department that’s risen tremendously in stature since I came to UMassvirtual in 1987. banquet, We’ve and a madedesign yoursome own t-shirt contest. thanks to the Barksdale fund, two were supported through the exceptional hires and improved our graduate and undergraduate programs. — Alejandro Our graduatesMorales have gone on UMass TRIPODS Institute, and two were supported through to do outstandingfaculty things. grants. We’re There very proudwas a wide of ourrange alumni. of exciting research carried out this summer, and many of the students presented ONLINE CONFERENCES A particular area atof an growth online Mathis our REU number conference of undergraduate organized by UConn. majors, The whichOne feature continually of the COVID-19-ridden exceeds expectations. environment More this and year more of our incoming studentsprojects recognize presented were the benefits of majoring in math. Wewas have the profusionalmost 1000of online majors academic in 7 areas:conferences. Actuarial I asked Science, Applied Math, Computing,“Circle Dynamics: Pure Arnold Math, Tongues” Statistics, by Rebecca Teaching Rosenblum, and anwith Individual Laura Colmenarejo concentration. to report Mathematics on her experiences is also— Ed. an essential part of any 21st centuryfaculty mentor education, Robin Youngas over 15,000 UMass students take our classes each year. “Hooklength Formulas for Semi-Standard Young Tableaux” by Thanks to the hardPeter workCassels, of withour facultysearch mentor committee, Alejandro our Morales tenure track position in Math Biology was filled by our top candidate: Assistant Professor“Exploring Brian theVan Naples Koten parking is an functions” expert byin Christoapplied Keller probability with and numerical analysis, performing computer simulations of molecularfaculty mentor systems Laura with Colmenarejo applications in biology, chemistry and materials science. We also had a very successful year in hiring 8 new“Clustering outstanding of Uveal VisitingMelanoma Assistant Patients” by Professors: Nathan Grant Siddhant with Agrawal, Panagiota Birmpa, Noriyuki Hamada, Kuan-Wen Lai, Jonathanfaculty mentor Simone Leili Shahriyari, Zahra Sinaei, Zheni Utic and Jiayu Zhai. Our new Marshall Stone VAP, Laura Colmenarejo Hernando, will join“Adjusted us in Per-Protocol Spring 2019. Analysis in Vaccine Efficacy Trials” by Erica Laidler with faculty mentor Ted Westling It was March 11, 2020 when we started to receive news about Our Newsletter, andAdditional the on-line projects, Faculty not presented News at theBriefs REU at conference: www.math.umass.edu,the online providetransition an due opportunity to COVID-19, toand highlight it was March some 13, of 2020 when it was made official. Spring 2019 lectures would be the outstanding work“Exploring of our Patient faculty Gene in Expression pushing in the Lung envelope Adenocarcinoma” of knowledge in mathematics and statistics each year: Assistant online for the rest of the semester and the spring break would by Joseph Cormier with faculty mentor Leili Shahriyari Professor Nestor Guillen spoke at the Austin workshop “Gerrymanderinggive us Steals time toElections: figure out Learn how that how was It’s possible. Done During and Howthat to Stop It,” and was part“Alternate of a Algorithms panel on for the School topic Choice” including by Morgan US DiPillaRepresentative with week, Jim I started McGovern receiving thisemails year; about Associate postponed Professorand canceled Paul Hacking was invitedfaculty to mentor lecture Mark at theWilson 2018 International Congress of Mathematicians;conferences. Surprisingly, Associate I also Professorsaw a post Alexeion Facebook Oblomkov by was awarded a Simons“Using Fellowship; Neural Networks Professors to Identify Markos Parameters Katsoulakis for Lane Changing and Luc Maria Rey-Bellet Monks Gillespie received (Colorado a major State Air University) Force grant asking to for develop performance guaranteesModel from in Trafficpredictive Data” bymodeling; Yaocao Chen Professor with faculty Andrea mentor Nahmod volunteers was to organize part of or a talkfeature in a virtual honoring conference. women On March in the Notices of the AMS; and UniversityQian-Yong Chen Distinguished Professor Panos Kevrekidis19, published I emailed her4 papers saying thatin the I would Nature love familyto co-organize of journals. such “Thermodynamic properties of billiards-like heat conduction a conference and/or give a talk. Within a week, we formed a Our Department model”hosted by 3 Zoe conferences Duan with faculty this past mentor year: Yao Li Associate Professorteam Annaof four organizersLiu was amongand five the weeks organizers later we sent of theour first32nd New announcement to the community. AlCoVE (an Algebraic “A data-driven method for invariant probability measures of England Statistical Symposium bringing together nearly 250 statisticiansCombinatorics to discuss emergingVirtual Expedition!) issues in took April place 2018; virtually Professor on nonlinear dynamical systems driven by non-Gaussian Levy Andrea Nahmod helped organize Women in Partial Differential EquationsJune 15-16, in March 2020, with2018; 12 andtop-level Associate research Professortalks and a Hongkunposter processes” by Liwen Ouyang with faculty mentor Jiayu Zhai th Zhang co-organized Mathematical Physics Perspective of Billards and Dominoessession with celebrating 12 posters from the researchers 70 birthdays at all stages. of PavelMoreover, Bleher and — Matthew Dobson Leonid Bunimovich in September 2017. this conference included social activities such as a scavenger CONFERENCES hunt, some virtual expeditions, math funny pools, and a happy UMass Amherst undergraduates Jonah Chaban, Artem Vysogorets, andhour. Jimmy Hwang worked as a team, led by Assistant Professor MatthewThe Dobson 32nd International, to produce conference the top-scoring in Formal project Power Seriesamong 7 competingWhile I was teamsorganizing at the AlCoVE, first everI was Student involved Competition in and Algebraic Combinatorics (FPSAC), the main conference another conference. Every year since 2013, I have attended a Using Modeling (SCUDEM) in Fall 2017. Three more SCUDEM teams led by Dobson also did very well in Spring 2018, in the field, was held online from July 6 to July 24, 2020. The conference called FPSAC (Formal Power Series in Algebraic receiving meritoriousorganizing mention committee and outstandingincluded Assistant mention. Professor Alejandro Combinatorics). Over the years, this conference is becoming Morales as chair, VAP Laura Colmenarejo, and PhD student more and more famous, and the number of submissions is We are very sad toWilliam have lostDugan. an Theimportant conference member had more of than our 600 faculty, registered Richard increasing S. Ellis every, who year. passedHowever, away there inare Julyat most 2018. 30 talks Richard and joined the department inparticipants 1975, and from also around taught the classes world andin Judaism an average and of morethe Torah usually as noan more adjunct than professor60 papers as of you Judaic could expectand Near to have Eastern in Studies. He was an internationally regarded expert in probability and large deviation theory, who also cared very much about the well-being of his students and colleagues, organizing sessions to relieve stress both inside and outside of the classroom. Richard will be truly missed. 2019-2020 Volume 35 17 We are also sorry to report the retirement of two important members of our faculty, Michael Lavine and Bill Meeks, in May 2018. Professor Lavine, a well-respected Bayesian statistician and a leader in our statistics group, had been a department member since 2008. Professor Meeks held the prestigious George David Birkhoff chair since joining the department in 1986; he is a world-renowned differential geometer and topologist, with a distinguished reputation in the area of minimal surfaces. The support of our alumni and friends is invaluable to us. We want to know how you are doing. Please send us your news, or stop in for a visit. – Nathaniel Whitaker DEPARTMENT OF MATHEMATICS & STATISTICS 2018 Volume 33 3 3 an M-F conference with a 9-5 schedule and two or three poster questions in the chat during the talk or at the end of the sessions. Then, the question came up. What are we doing with talk. FPSAC? Are we going online? Is this even possible? After many • Technical support and host, who will be in charge of meetings, some calls to the community, and some decisions, NEW handling CHALLENGE the technical aspect PROBLEMS of letting participants in, MATHEMATICSthere was a team aiming to get& this conference organized. muting when necessary, and making sure that there are no Leading this team, there was Alejandro H. Morales from our Herestrange is a selection behaviors. of some of the more challenging STATISTICSdepartment, and I said yes when he asked for help. His proposal problems• All the peoplefrom theassigned 2018 to Jacob-Cohen-Killamthese roles must be co-host prize as was to have three contributed talks for three days a week exam.soon Three as they additionaljoin the meeting, prize and exam the host problems should not are be NEWSLETTERand for three weeks in July. Three, three, and three. And yes, includedassigned in to the any Awardsof these roles Dinner apart from article technical on pagesupport. 14. .. three poster sessions, one each week this time, and trying to ...... Social events are more than important, they are essential. They accommodate three time zones. But no, we did not have three help us keep the community active and engaged, as well as EDITEDmonths to organize BY it, we did in two. FPSAC took place virtually Problemcreate a nice environment1. Compute for the conference. volume of the 2018– on July 5-24, and among the social activities, we had virtual dimensional• Organize short simplex breaks (coffee breaks) during talks with Richard S. Elliscoffee breaks Robert with activities, Kusner a banquet, happy hours, and two topics and breakout rooms with a reasonable number of 2018 puzzle events. {(t1,participants ... , t2018 inR each room. t1 t2018 . These are my tips for organizing a virtual conference...... • Organize long breaks (for lunch or happy hour time) at the DESIGNEDConference talks BY—general ideas end of each)∈ session, so: 0 participants ≤ ≤ ··· can ≤ engage ≤ in 1}further • 30 minutes talk, including questions. Problemdiscussion 2. and/or Given socialize. numbers a1, a2, a3, a4, suppose Brigette McKenna • Organize small activities such as scavenger hunts, puzzles, • Make sure to be explicit about the available time for the an is defined recursively as speakers. Since interrupting during an online talk is polls, topics for conversations, photo competitions, etc. complicated or cannot be done as discreetly as we would • aBe =inclusive (a + whilea +organizing a + a the)/4. activities and keep inn mindn−1 that theren−2 willn−3 be undergraduaten−4 and graduate IN COOPERATIONlike, letting the WITH speakers know that they have 30 minutes students, or even postdocs and faculty, that are new to the and that the time will be strictly managed is usually enough. Show that the sequence {a } converges and • No more than 2 talks with no break. community. n Q.Y. CHEN P. FLAHERTY O. GWILLIAM • For a day conference, 6 talks is a reasonable number. For calculate• Don’t beL =afraid lim n→∞to ask an . for...... videos! Elevator speeches are P. HACKING J. HOROWITZ S. HROBAR very interesting, a good practice for junior mathematicians a conference that extends to a few days, reduce the number V. LYZINSKI I. MIRKOVICto 3 talks per day. A. MORALES and fun to record and watch! You can find my Problemelevator 3.speech Consider for FPSAC a regular https://www.youtube.com/ tetrahedron with F. PEDIT A.• RAYMONDTake into account the C.time RUSSELL zones of the audience before fixing the schedule. edgeswatch?v=1HThJ9cdnSE&feature=youtu.be&t=4m12s of length 1. What is the length of the shortest. N. WANG N. WHITAKER R. YOUNG • A pre-registration form is a good way to obtain this kind of loopSoftware on itsand surface technical which support surrounds two vertices? .. information. • Try to avoid Google apps to organize your conference. That • Record the talks if the speakers agree. Offer the option of ...... includes Google sites, Google forms, Google Docs, etc. The Department of Mathematicsrecording theand talk Statistics and letting thepublishes speaker decide afterward Problem• Zoom is 4.a very How standard many app 3×3 for arrays conferences are therein the suchUS. its annual newsletter for inalumni case they and want friends.to check the You recording. are Also, ask the thatHowever, (i) entries participants include in allother the countries digits (likefrom for 1 instance through important, and we want to hearspeakers from to you! include Please “This contact talk is being us at recorded” in their 9, andFrance) (ii) mayentries not be in allowed every to row access and Zoom column with their are work in [email protected] to sharefirst yourslide. news, let us know how increasingcomputer. order? Be open to experimenting with other options. you are doing, and learn• waysRemember to become to be inclusive involved and includewith the a variety of speakers • For the Zoom extra license, be aware that it takes two weeks including minorities and speakers at different stages in to activate it and you need to activate it also in your profile Department. Our website is a valuable resource for current their careers. Problemwhen you 5 create. .Let the E Zoom be the link. coefficients in the happenings and news, so •we encourageAsk the speakers you for to preferences visit us regularly about dates and times. • Include a password forn your conference and give a nice hint ∞ xⁿ n nn! at www. math.umass.edu• Offer the speakers the opportunity to practice their settings expansion:in your emails, .sec sox+tan the participants x = E can. ⁿ guess=0 the password. before their talks. ShowHave in that mind they that satisfy students E will =E also =1 participate, and for nbut≥1 it should not be easy to find out 0by searching1 the hint. On a more somber note,Relevant we mourn roles to theconsider passing during on the 2talks July • Chair for each session who will be in charge of introducing • ...Find out if you can use grant funding to pay for a company 2018 of our dear colleague Richard S. Ellis, an internationally that edits your videos. It is not the craziest thing, the edits the speakers, and can also remind everyone about the regarded probabilist, and astatement good friend of respect to and many inclusion of usat the on beginning of each are usually really good, and not much funding is needed for section. an online conference. campus and in the community. It’s an immeasurable loss to Problem 6. Let An be the set of all subsets S of our Department. For many• Chatyears moderator Richard who edited will thebe responsible annual for asking the • Save the chat, so you can send the comments and questions {1, 2,to ...,the n}speakers such since that they S contains will not have the access size to | themS| of later. S. Let Newsletter and monthly News Briefs, and I — your current Bn be the set of all S in An which are minimal, i.e., editor — enjoyed working with him on both for much of the if S contains some subset T in An then T = S. Show past decade. As I re-drafted the letter soliciting briefs this that the number bn of elements of the set Bn is the 18 DEPARTMENT OF MATHEMATICS & STATISTICS th September, I realized it was based on Richard’s traditional n Fibonacci number Fn (here F1 = 1 = F2 and after text, passed down from him to me several years ago. Both that Fn = Fn−1 + Fn−2). this Newsletter and the News Briefs have become Department traditions, shaped by each of us who has taken on the role of Problem 7. Evaluate π/2 1 editor, but Richard’s influence looms large. He and I shared many common interests outside mathematics, particularly an intellectual curiosity about languages and literature, and both Send solutions, comments, or feedback via email of us have been deeply committed to carry on the tradition of to Professor Franz Pedit 2 • Monitor the waiting room and make sure that all RECOGNIZING STUDENT SUCCESS DEPARTMENTparticipants HEAD’S accepted in MESSAGE the talks have their full name in Latin characters before entering the room. The traditional awards dinner was not held owing to COVID-19, I’d like to welcome• youFor to university our Newsletter Zoom accounts, as the only new email Department addresses from Head. but Iwe officially list the awards started here. Congratulations on 21 January to all students listed! 2018. It’s a true honorthe – same and universitysomewhat are daunting allowed to –be to alternative follow in hosts. the footstepsAlthough ofin-person Farshid graduation Hajir, who activities were not possible now serves as Vice ProvostMake sure of youAcademic include more Affairs than oneand person did ain fantastic case there jobthis in year,his 3the years department as Head. organized I take anover online ceremony for a department that’s risenare any tremendously issues. in stature since I came to UMassgraduating in 1987. students, We’ve madewhich somecan be found at https://www. youtube.com/watch?v=xmTePcTz9pI. exceptional hires Organizationaland improved tips our graduate and undergraduate programs. Our graduates have gone on to do outstanding• things.Weekly We’re or biweekly very meetingsproud of are our at fixed alumni. times to help with Graduate Student Awards keeping the organization going. Distinguished Thesis Award: Shuaimin Kang for her thesis • Find a forum (Slack, hackmd, GoogleDrive, etc) where A particular area of growth is our number of undergraduate majors, which“Latent continually Class Models exceedsfor At-Risk expectations. Populations” More and more of you write summaries of the meetings, to-do lists, and a our incoming students recognize the benefits of majoring in math. DistinguishedWe have almost Teaching 1000 Award:majors Angelicain 7 areas: Simonetti Actuarial Science, brainstorming section. Applied Math, Computing, Pure Math, Statistics, Teaching and an Individual concentration. Mathematics is also an essential • Find an instant way to communicate as a group (Whatsapp, st Undergraduate awards part of any 21 centuryFacebook education, Messenger, as over Google 15,000 Doc, GroupMe,UMass students etc) during take our classes each year. Honors research and theses the talks, and avoid using the private Zoom chat. These students completed honors theses in mathematics or Thanks to the hard• Trywork to minimizeof our search the number committee, of emails our to the tenure participants track position in Math Biology was filled by our top candidate: statistics this year: Assistant Professor Brianand speakers Van Koten by summarizing is an expert information. in applied probability and numerical analysis, performing computer Robin Armstrong, Ellen Burton, Max Cope-Flanagan, Lucy • Emails to participants should be direct and contain the simulations of molecular systems with applications in biology, chemistryGrossman, and materials Patrick Lei, science. Roy Siegelmann We also had a very successful information and the links accessible. year in hiring 8 new outstanding Visiting Assistant Professors: SiddhantREU Agrawal students , Panagiota Birmpa, Noriyuki Hamada, • Make sure to include a statement of respect and inclusion Kuan-Wen Lai, Jonathan Simone, Zahra Sinaei, Zheni Utic and JiayuThe Zhai following. Our newstudents Marshall participated Stone in VAP, an LauraREU (research Colmenarejo on your website, and include it in one of your emails to the experience for undergraduates) this year: Hernando, will join usparticipants. in Spring 2019. Robin Armstrong, Ellen Burton, Peter Cassels, Owen Davey, • Registration of participants should be mandatory in order Nuha Futa, Jimmy Hwang, Pranav Kalkunte, Long Le, Max Our Newsletter, and tothe get on-line the link forFaculty the conference. News Briefs This allows at www.math.umass.edu, the organizers provide an opportunity to highlight some of Liu, Mridul Madan, Nghia Nguyen, Manan Patel, Advait Sinha, the outstanding workto of estimate our faculty the number in pushing of participants the envelope if there ofare knowledge any in mathematics and statistics each year: Assistant Matthew Trainor Professor Nestor Guillenrestrictions. spoke at the Austin workshop “Gerrymandering Steals Elections: Learn how It’s Done and How to Outstanding Academic Achievement in Actuarial Science • Make sure you are aware of the limitations of the software Stop It,” and was part of a panel on the topic including US RepresentativeJulianne Jim Higgins,McGovern Xiaoxi this (Jenelle) year; AssociateKang, Indrius Professor Kveraga, Paul you are using depending on the role of the participants Hacking was invited to lecture at the 2018 International Congress of Mathematicians;Madelyn Nelson, Ruoying Associate Zhao Professor Alexei Oblomkov was (host, co-host, participant) and the software from which awarded a Simons Fellowship; Professors Markos Katsoulakis and LucOutstanding Rey-Bellet Academic received aAchievement major Air Forcein Applied grant toand develop the participants are attending the conference (phone, Computational Math performance guaranteeslaptop, in tablet predictive / Linux, modeling;Macintosh, Windows, Professor Chrome). Andrea Nahmod was part of a feature honoring women in the Notices Jensen Beaumont, Daria Bobrova, Max Cope-Flanagan, Brian of the AMS; and University• Ask speakers Distinguished to provide another Professor method Panos of contact Kevrekidis (apart published 4 papers in the Nature family of journals. Dang, Collin Giguere, Joshua Marulis, Roman Sacks, Adam from email) in case they do not show up and do not answer Viola, Devon Yu, Jiaming Yuan Our Department hostedemail. 3 conferences this past year: Associate Professor Anna Liu was among the organizers of the 32nd New Outstanding Academic Achievement in Pure Math & England Statistical Symposium bringing together nearly 250 statisticiansIndividual to discuss Concentration emerging issues in April 2018; Professor Yes, I know these are many things to have in mind and that it Andrea Nahmod helped organize Women in Partial Differential EquationsThomas in MarchBertram, 2018;Owen andDavey, Associate Alexander ProfessorFischer, Alexandra Hongkun seems complicated. However, I can tell you that you do not need th Zhang co-organized Mathematical Physics Perspective of Billards and DominoesMcGuire, Patrick celebrating Lei, Nathan the 70 Sherman, birthdays Matthew of Pavel Trainor, Bleher and to organize hotels, conference rooms, speakers and participants’ Leonid Bunimovich in September 2017. Yankai Xiang trips, funding for travel, etc. I just have two final suggestions. Outstanding Academic Achievement in Statistics Ask for help. Seminars and conferences are already Timothy Cauley, Delaney Johnson, Derrick Liu, John Milmore, UMass Amherst undergraduateshappening all over Jonahthe world Chaban and many, Artem of us Vysogorets have some , and Jimmy Hwang worked as a team, led by Assistant Mariah Morse, Sirisha Nouduri, Ilina Shah, Shuyi Tan, William Professor Matthewexperience Dobson we’d, to be produce happy to share. the top-scoring project among 7 competing teams at the first ever Student Competition Zhang Using Modeling (SCUDEM) Enjoy the conferencein Fall 2017. and make Three sure allmore the SCUDEM organizers can teams led by Dobson also did very well in Spring 2018, Outstanding Academic Achievement in the Teaching participate actively in those parts they are most interested in. receiving meritorious mention and outstanding mention. Concentration Ellen Burton, David Dam, Lindsey Thunberg, Tongyu Zhou We are very sad to have lost an important member of our faculty, RichardM.K. BennettS. Ellis award, who for passed outstanding away achievement in July 2018. in geometry Richard joined the department in 1975, and also taught classes in Judaism and the TorahThe asRobert an adjunctand Veronica professor Piziak Fundof Judaic endows and an annualNear Easternprize Studies. He was an internationally regarded expert in probability and large deviation theory, who also cared very much about the well-being of his students and colleagues, organizing sessions to relieve stress both inside and outside of the classroom. Richard will be truly missed. 2019-2020 Volume 35 19 We are also sorry to report the retirement of two important members of our faculty, Michael Lavine and Bill Meeks, in May 2018. Professor Lavine, a well-respected Bayesian statistician and a leader in our statistics group, had been a department member since 2008. Professor Meeks held the prestigious George David Birkhoff chair since joining the department in 1986; he is a world-renowned differential geometer and topologist, with a distinguished reputation in the area of minimal surfaces. The support of our alumni and friends is invaluable to us. We want to know how you are doing. Please send us your news, or stop in for a visit. – Nathaniel Whitaker DEPARTMENT OF MATHEMATICS & STATISTICS 2018 Volume 33 3 3 in the Department of Math & Stat to the student of highest Foundation grants “Moduli Spaces: New Directions” and standing in Math 461. “ELGA. Latin American School of Algebraic Geometry and Ellen Burton Applications.” Student Leadership Award NEWPhoto by www.plainformstudio.comCHALLENGE PROBLEMS Julianne Higgins, President and former treasurer of the UMass MATHEMATICS & Here is a selection of some of the more challenging chapter of the Association for Women in Mathematics Panos Kevrekidis was also on sabbatical, and contributed a STATISTICSChan Kim, for his leadership in the teaching club and his service problemsdetailed report from in late the June. 2018 Jacob-Cohen-Killam prize as a peer advisor exam. Three additional prize exam problems are NEWSLETTERWinners of the Jacob Cohen Killam prize exam includedSome 15 years in theago, Awardscurrent Department Dinner articleHead, Professor on page Nate 14. .. Pranav Garg , First place ...... Whitaker and I assembled a very bright team of 3 excellent Gary Wei, Second place UMass undergraduates to work on a topic of tumor dynamics. EDITEDKirin Sarangkasari BY , Third place ProblemWe were interested 1. Compute in how vascular the volumenetworks formof the and 2018– provide Dhruba Basu, Joshua Bornstein, Stuart Lustig, Matthew Miller, dimensionalthe tumor with simplexnutrients (in a process called angiogenesis) Richard S. EllisFourth place (tie)Robert Kusner in the presence of an extracellular matrix and various 2018 Leon Emory Lincoln and Robert Bradley Lincoln Scholarship {(othert1, ...elements , t2018 potentiallyR inhibitingt1 this processt2018 (so-called. The donation is from the estate of Annah Silsby Lincoln, ...... inhibitors). One of the talented undergraduates involved in this DESIGNEDdaughter of Leon BY Emory and sister to Robert Bradley, both quest, that eventually)∈ led :to 0 a ≤ paper ≤ published ··· ≤ in August ≤ 1} 2007 graduates UMass Amherst. This scholarship is given to a math Problemin Mathematical 2. andGiven Computer numbers Modelling a1, a was2, a 3called, a4, supposeHeather Brigettemajor of McKenna high academic standing. Harrington. Heather went on to win a Goldwater scholarship an is defined recursively as Li Shandross and then a prestigious NSF fellowship to go and study for her Marcia Lockhart Ruma Scholarship PhDa at =Imperial (a + College. a + Shea continued + a )/4. on in Mathematical Established by Marcia Lockhart Ruma, Class of ‘65, and her Biologyn and n−1its interfacen−2 withn−3 the techniquesn−4 stemming from IN COOPERATIONhusband Charles, Class WITH of ‘64 and MBA ‘65, this award is given to Pure Mathematics in the area of Topological Data Analysis and an undergraduate major in Math & Stat who has demonstrated Showbecame that an Associate the sequence Professor {ata nthe} converges University of and Oxford, one Q.Y. CHEN P.financial FLAHERTY need. O. GWILLIAM calculateof the top institutions L = limn→∞ in the an .UK ...... and around the globe in terms P. HACKING J.Cynthia HOROWITZ Camacho S. HROBAR of its academic impact. In an unrelated development, less than Robert and Lynne Pollack Actuarial Award 5 years ago, I learned about an exciting new computational V. LYZINSKI I. MIRKOVIC A. MORALES This scholarship is awarded through a generous donation from Problemtechnique called 3. deflation. Consider Suppose a regular that youtetrahedron use a root-finding with F. PEDIT A.Robert RAYMOND and Lynn Pollack to C.an outstandingRUSSELL student in actuarial edgesalgorithm of lengthlike the 1.Newton-Raphson What is the lengthmethod ofand the you shortest find N. WANG N.science. WHITAKER R. YOUNG loopa solution. on its Now, surface suppose which that your surrounds problem istwo very vertices? complex .. Siqi Gong (possibly bearing infinite degrees of freedom) and therefore SCUDEM .has...... not only one but many solutions. How do you find other The Department of MathematicsTwo teams from and UMass Statistics competed publishes in this event, in which Problemsolutions, given 4. that How you manyalready 3×3have one?arrays Deflation are there gives suchyou its annual newsletter studentsfor alumni develop andmodels friends. using differential You are equations. The first thata systematic (i) entries way to include “factor out” all thethis firstdigits solution from and1 through solve a important, and we want toteam hear was from rated outstandingyou! Please (the contact highest possibleus at rating) “revised problem” that allows to find a second root. Deflating Team 1: Frank Cole, Vishvesh Gandhi, Alexander Shilcusky 9,then and two (ii) roots, entries one can in try every to find row a third and one column and so areon. inThis [email protected] toTeam share 2: Minh your Nguyen, news, Xindong let us Tian, know Freya how Zhang increasingyoung, freshly order? appointed Associate Professor, again at the you are doing, and learn ways to become involved with the University of Oxford and its Mathematical Institute, studying Department. Our website is a valuable resource for current deflation was named Patrick Farrell. With Patrick and former happenings and news, so SABBATICALwe encourage you NEWS to visit us regularly Problempostdoctoral research5. .Let Efellow,n be theVisiting coefficients Assistant Professor in the and expansion:well-remembered .sec Chief x+tan Undergraduate x = ∞ E xⁿ . Advisor,ⁿ n=0 n n!Prof. Stathis at www. math.umass.edu Jenia Tevelev has spent the 2019- Charalampidis now of Cal Poly San Luis Obispo, we wrote a 2020 academic year conducting paperShow on using that deflation they satisfyfor finding E0 =solutionsE1 =1 ofand nonlinear for n ≥1partial research, teaching, and mentoring differential equations that appeared in 2017 in Communications On a more somber note, we mourn the passingat the Universidad on 2 July Católica de Chile ... in Nonlinear Science and Numerical Simulation. 2018 of our dear colleague Richard S. Ellis, anin internationallySantiago. His sabbatical activities Little did I know about the fact that these highly visible regarded probabilist, and a good friend towere many generously of us onsupported by the young colleagues at Oxford (Heather and Patrick) knew each Fulbright Scholarship “New Frontiers campus and in the community. It’s an immeasurable loss to Problemother well and 6. Letworked An beclosely the together,set of all until, subsets upon S theirof of Algebraic Geometry”, Simons our Department. For many years Richard edited the annual {1,invitation, 2, ..., n}the suchthree ofthat us ended S contains up spending the asize good | Sfraction| of S. ofLet Fellowship and National Science Newsletter and monthly News Briefs, and I — your current Bn be the set of all S in An which are minimal, i.e., editor — enjoyed working with him on both for much of the if S contains some subset T in An then T = S. Show past decade. As I re-drafted the letter soliciting briefs this that the number bn of elements of the set Bn is the 20 DEPARTMENT OF MATHEMATICS & STATISTICS th September, I realized it was based on Richard’s traditional n Fibonacci number Fn (here F1 = 1 = F2 and after text, passed down from him to me several years ago. Both that Fn = Fn−1 + Fn−2). this Newsletter and the News Briefs have become Department traditions, shaped by each of us who has taken on the role of Problem 7. Evaluate π/2 1 editor, but Richard’s influence looms large. He and I shared many common interests outside mathematics, particularly an intellectual curiosity about languages and literature, and both Send solutions, comments, or feedback via email of us have been deeply committed to carry on the tradition of to Professor Franz Pedit 2 Fall 2018 writing an application for the very highly competitive mentored a junior researcher (analogous to our VAPs). In general, DEPARTMENTLeverhulme HEAD’S Trust Visiting ProfessorshipMESSAGE scheme for a potential it was an ultra busy and extremely exciting period full of new visit at the University of Oxford. Thankfully, we were lucky ideas, directions and collaborations, ranging from exponential I’d like to welcomeenough you to beour awarded Newsletter such a fellowship,as the new enabling Department me to spend Head. asymptotics I officially to modeling started quasicrystals on 21 January and from plasma and 2018. It’s a true honorthe entire – and year somewhatat the University daunting of Oxford. – to Indeed, follow I inarrived the footstepsfluid waves of Farshidto studying Hajir τ proteins, who and cancer stem cells! Of now serves as Vicehere Provost in Oxford of (fromAcademic where IAffairs am currently and writingdid a fantasticstill under jobcourse, in his I continued3 years as to Head.mentor I undergraduatetake over student Jimmy a department that’slockdown!) risen tremendously in early September in andstature was immediatelysince I came struck to UMassby Hwang in 1987. (who completed We’ve made his honors some thesis and is now admitted in exceptional hires theand beauty improved of Oxford our as graduatea town, the andability undergraduate to walk and/or bike programs. the PhD Our program), graduates PhD students have Ryangone Ross on and George Tsolias, to do outstandingeverywhere things. We’re and the very remarkable proud ofstrength our alumni. and diversity of the and Visiting Assistant Professor Mithun Thudiyangal remotely Mathematical Institute and of the University. Of course, there at UMass, and also completed a project and paper submission A particular area wereof growth many nontrivial is our numbersteps along of the undergraduate way. Getting one’s majors,children whichwith Applied continually Math M.S. exceeds student expectations. Jennifer Sullivan More based onand her more of to school within the UK system was a particular challenge for earlier honors thesis. I was especially excited about the spring, our incoming studentsus, even recognize getting a bank the accountbenefits here of turned majoring out to in be rathermath. whenWe have various almost trips 1000to different majors Universities in 7 areas: and Actuarialcountries andScience, Applied Math, Computing,complicated, butPure gradually Math, and Statistics, despite a Teachingnumber of hurdlesand an we Individual conferences concentration. were scheduled. Mathematics is also an essential st part of any 21 centurygot acclimated education, and spent as over a really 15,000 pleasant UMass Fall semester students here. take ourBut classes then, there each came year. COVID! And, of course, everything The weather was quite mild throughout the Fall and Winter and changed, as it has for almost all of us. The UK was one of the Thanks to the hardenabled work a numberof our ofsearch trips and committee, short visits bothour tenurewithin the track UK positionworst, if innot theMath worst Biology hit country was infilled Europe. by Theour initialtop candidate: less Assistant Professor(e.g. Brian to University Van Koten of Essex, is to an Imperial expert College, in applied to the University probability strict and reaction numerical (towards analysis, social interactions performing and distancing) computer was simulations of molecularof Cambridge systems and some with within applications Europe), for in lectures, biology, in parallel chemistry quickly and observed materials to leadscience. to unprecedented We also had and a veryunexpected successful year in hiring 8 newwith outstanding numerous seminars Visiting and colloquia Assistant at Oxford. Professors: Siddhantresults Agrawal and was, rapidlyPanagiota changed, Birmpa although, Noriyuki its impact wasHamada deep , Scientifically, it was a remarkable experience and a “true and lasting in terms of the rapid progress of the pandemic. Kuan-Wen Lai, Jonathansabbatical” inSimone the intended, Zahra (as far Sinaei as I can, Zhenitell) sense Utic of the and term. Jiayu Lockdown Zhai. Ourwas imposednew Marshall after mid-MarchStone VAP, although Laura we Colmenarejo as a Hernando, will joinFirst us off, in the Spring number 2019. of seminars and talks and visitors and family started observing it already earlier and we are still internal journal clubs and even conferences going on on a rolling observing it despite the gradual relaxation of associated Our Newsletter, andbasis the here on-line is truly staggering. Faculty News Almost Briefs literally, at one www.math.umass.edu, could spend measures. Thankfully,provide an here opportunity in the UK, there to highlight was a high somequality of the outstanding workdays on of end our doing faculty nothing in pushingmore than thegoing envelope to interesting of knowledgetalks supply in system mathematics of goods that and enabled statistics (despite each the year: strains Assistant on it Professor Nestor nearlyGuillen one spokeafter another. at the AustinThey also workshop have excellent “Gerrymandering programs of by everyone Steals using Elections: it concurrently) Learn how getting It’s food Done and and supplies How to Stop It,” and was partpublic of lectures a panel about on Mathematics the topic including and its applications, US Representative as well without Jim going McGovern outside one’s this door. year; Here, Associate as in the US, Professor the number Paul as numerous very distinguished visitors in their high profile of cases is still very high and even in Oxfordshire, there have Hacking was invited to lecture at the 2018 International Congress of Mathematicians; Associate Professor Alexei Oblomkov was lecture series. I went back to learning -I hope- a good deal been more deaths in just this one county than in some much awarded a Simonsabout Fellowship; tumor biology Professors through different Markos lecture Katsoulakis series and andweekly Luc bigger Rey-Bellet (over 10 times received in size) a European major Air countries. Force grant to develop performance guaranteesdiscussions in withpredictive both a modeling;math biologist Professor and also Andreaseparately Nahmod COVID was haspart also of ahad feature a striking honoring impact women on research in the Notices of the AMS; and Universitywith a tumor Distinguished biologist. I also learned Professor a little Panos about Alzheimer’s Kevrekidis mobilizing published the 4 efforts papers of ina huge the Naturenumber offamily researchers of journals. around and Parkinson’s, i.e., neurodegenerative diseases and their the globe from Biology, Epidemiology and also Mathematics Our Department modeling.hosted 3 Of conferences course, I did thisnot forgetpast year:about my Associate favorite areas Professor and Statistics Anna towardsLiu was the among direction the of organizersattempting to of help the with 32 nd New England Statisticalof Symposiumnonlinear PDEs bringing and nonlinear together waves nearly especially. 250 I connected statisticians understanding to discuss theemerging pandemic issues from indifferent April 2018;perspectives. Professor To Andrea Nahmodwith helped an engineer organize who Women is doing in state-of-the-art Partial Differential experiments Equations that effect, in March I decided 2018; to try and to Associateassemble a team Professor of collaborator Hongkun in fluids (on the so-called rogue waves) and collaborated with friends and researchers from Universityth of Sevilla, University of Zhang co-organizeda plasma Mathematical scientist exploring Physics nonlinear Perspective waves ofwithin Billards variants and DominoesIllinois at Urbana celebrating Champaign the and 70 JRC birthdays in Italy, in of order Pavel to look Bleher and Leonid Bunimovichof the in Maxwell’sSeptember equations. 2017. Of course, I also continued my into epidemiological models for the spread of the pandemic. We iterations with Patrick on deflation techniques for highly are focusing on some regions that we know/understand better UMass Amherst undergraduateschallenging 3d problems Jonah (using Chaban state-of-the-art, Artem finiteVysogorets element , andand haveJimmy attempted Hwang to offerworked more as detailed a team, models led byaccounting Assistant Professor Matthewtechniques Dobson coupled, to produce to deflation) the top-scoring and with Heather project (on among the for 7 somecompeting of the particular teams at features the first of theever spreading Student of Competitionthis Using Modeling (SCUDEM)dynamics of vortices in Fall in 2017.atomic gasesThree and howmore to SCUDEM use algebraic teams disease, led by such Dobson as most also notably did thevery role well of inthe Spring asymptomatic 2018, receiving meritorioustechniques mention to solve and the outstandingassociated equations mention. efficiently, but also infectious individuals. Another point of emphasis is to offer to find all possible solutions for small numbers of vortices of the a spatial analysis of the dynamics of the pandemic (instead of relevant polynomial equations). I supervised a Master’s Thesis just a cumulative “well mixed” perspective of it), as well as the We are very sad toin haveMathematical lost an Physics, important I mentored member two graduate of our students faculty, (one Richard attempt S. to Ellis split, thewho model passed into multiple away in interacting July 2018. populations Richard joined the department inin 1975, tumor anddynamics also andtaught one inclasses computational in Judaism methods), and Ithe also Torah of different as an adjunctages, due toprofessor the clear ofmanifestation Judaic and of theNear diversity Eastern Studies. He was an internationally regarded expert in probability and large deviation theory, who also cared very much about the well-being of his students and colleagues, organizing sessions to relieve stress both inside and outside of the classroom. Richard will be truly missed. 2019-2020 Volume 35 21 We are also sorry to report the retirement of two important members of our faculty, Michael Lavine and Bill Meeks, in May 2018. Professor Lavine, a well-respected Bayesian statistician and a leader in our statistics group, had been a department member since 2008. Professor Meeks held the prestigious George David Birkhoff chair since joining the department in 1986; he is a world-renowned differential geometer and topologist, with a distinguished reputation in the area of minimal surfaces. The support of our alumni and friends is invaluable to us. We want to know how you are doing. Please send us your news, or stop in for a visit. – Nathaniel Whitaker DEPARTMENT OF MATHEMATICS & STATISTICS 2018 Volume 33 3 3 of COVID’s effects to different age groups. Below is a list of donors to the department during the period For now, my family and I are just hoping to get back — a 2019-10-01 to 2020-09-30. We greatly appreciate your support! nontrivial exercise in its own right. Amid countless cancellations (including also our first batch of tickets for July!), and with only NEWDonald C. CHALLENGE Abbott PROBLEMS MATHEMATICStwo companies flying from Europe & to Boston at the moment, Christina Abel ‘86 we are hoping to catch a flight of one of them to be able to HereActuaries’ is aClub selection of Hartford-Springfield of some of the more challenging STATISTICSsafely return to Amherst and prepare for what promises to be problemsAmerican Online from Giving the Foundation 2018 Jacob-Cohen-Killam prize a completely unique, in my 20 years of experience at UMass, exam.Geraldine Three Amprimo additional ‘75 prize exam problems are NEWSLETTERFall semester! The Oxford experience was a remarkable one, but includedHenri V. Azibert in the‘73 & Awards Susan (Hubbard) Dinner Azibert article ‘75 on page 14... June L. Bacon for now we are all just hoping for a COVID vaccine and for the ...... return of our world to a more stable, more safe and healthy state, John B. Baillieul ‘67 & Patricia (Pfeiffer) Baillieul ‘68 EDITEDto the degree BY that this may be possible. I certainly hope that this ProblemJoan (Bracker) Barksdale1. Compute ‘66 & Edgar the W. volume Barksdale, of Jr. the 2018– materializes between the time that these lines are written and dimensionalKenneth H. Barrows simplex ‘60 & Betsy (Howes) Barrows ‘64 Richard S. Ellisthe time that Robertyou are reading Kusner them! Wendell A. Berry ‘75 Philip S. Blau ‘92MS,’96Ph.D.2018 {(t1, ... , t2018 R t1 t2018 ...... David J. Bookston ‘96 Daniel D. Bourdeau)∈ ‘70 : 0 ≤ ≤ ··· ≤ ≤ 1} DESIGNED BY Bradford S. Nichols ‘08 & Emily Braley ‘07 Given numbers a , a , a , a , suppose Brigette McKenna ProblemGail Brittain ‘64MA 2. 1 2 3 4 aCarln is J. definedBritton, Jr. ‘86MED recursively & Margaret as (Stanne) Britton ‘84,’85MED Brown University Jennifer Burrill ‘97MS an = (an−1 + an−2 + an−3 + an−4)/4. IN COOPERATION WITH Katherine Burrill ‘96MS Ann (Chandonait) Celino ‘73 ShowCarol A. that Chanen the sequence {an} converges and Q.Y. CHEN P. FLAHERTY O. GWILLIAM calculateJames J. Chanen L = ‘64 lim n→∞ an...... P. HACKING J. HOROWITZ S. HROBAR Yue Chang ‘17MS,’18Ph.D. V. LYZINSKI I. MIRKOVIC A. MORALES Qiang Yu ‘99MS & Zhixiong Chen ‘98MS,’02Ph.D. New VAPs having fun on Zoom ProblemFrances Chevarley 3. ‘69 Consider a regular tetrahedron with F. PEDIT A. RAYMOND C. RUSSELL edgesRichard ofD. Coccilength ‘06,’06,’08MS 1. What & Alexandrais the length Cocci-Smart of the ‘08,’08 shortest N. WANG N. WHITAKER R. YOUNG loopRichard on A. itsCoco surface ‘75,’78MA which surrounds two vertices? .. Elizabeth (Witowski) Colby ‘69 .Paul...... M. Conlin ‘88 & Jill J. Conlin The Department of Mathematics and Statistics publishes ProblemD. John Coparanis 4. ‘52How many 3×3 arrays are there such its annual newsletter for alumni and friends. You are Peter J. Costa ‘84Ph.D. & Anne R. Costa thatCarol (i)(Tarr) entries Cox ‘63 *include all the digits from 1 through important, and we want to hear from you! Please contact us at 9,William and H.(ii) Cox, entries Jr. ‘64 in every row and column are in [email protected] to share your news, let us know how increasingBoxuan Cui ‘10,’12MS order? you are doing, and learn ways to become involved with the Leonard L. Dalton ‘61 & Leona (Mabie) Dalton ‘61 Department. Our website is a valuable resource for current Ashley DaSilva ‘07 Kyle DeSormier ‘15 Problem 5. .Let En be the coefficients in the happenings and news, so we encourage you to visit us regularly Nicolas DiCiaccio expansion: .sec x+tan x = ∞ E xⁿ. ⁿ n=0 nn! at www. math.umass.edu Michael A. Diehl ‘07MS,’08Ph.D. Elizabeth (Lombardi) Doane ‘70MA Show that they satisfy E0 =E1 =1 and for n≥1 Neil F. Doherty On a more somber note, we mourn the passing on 2 July David... J. Ellenbogen ‘84MED 2018 of our dear colleague Richard S. Ellis, an internationally Keith R. Ferland ‘67MA,’73Ph.D. & Gloria (Picard) Ferland ‘68MA regarded probabilist, and a good friend to many of us on Fidelity Investments Charitable Gift Fnd campus and in the community. It’s an immeasurable loss to Jonathan W. Fienup Let ‘96MS A be the set of all subsets S of ProblemSheila (Ryan) Flynn 6. ‘55 n our Department. For manyMonohedral years Richardspiral tiling edited contributed the by annual Julien Brenneck {1,Mary 2, Francis ..., n} Brzezenski such that ‘56 S contains the size |S| of S. Let Newsletter and monthly News Briefs, and I — your current Bn be the set of all S in An which are minimal, i.e., editor — enjoyed working with him on both for much of the if S contains some subset T in An then T = S. Show past decade. As I re-drafted the letter soliciting briefs this that the number bn of elements of the set Bn is the 22 DEPARTMENT OF MATHEMATICS & STATISTICS th September, I realized it was based on Richard’s traditional n Fibonacci number Fn (here F1 = 1 = F2 and after text, passed down from him to me several years ago. Both that Fn = Fn−1 + Fn−2). this Newsletter and the News Briefs have become Department traditions, shaped by each of us who has taken on the role of Problem 7. Evaluate π/2 1 editor, but Richard’s influence looms large. He and I shared many common interests outside mathematics, particularly an intellectual curiosity about languages and literature, and both Send solutions, comments, or feedback via email of us have been deeply committed to carry on the tradition of to Professor Franz Pedit 2 Christine (Paratore) Fraser ‘84 James A. O’Keeffe ‘75MA DEPARTMENTRobert F. Fredette HEAD’S ‘74 & Louise MESSAGE (Faille) Fredette ‘74 Corinne (Desautels) O’Reilly ‘96 Mary Ann Godbout ‘74MA Karnig Ovian “60S & Diana (Eksoozian) Ovian ‘60 I’d like to welcomeWilliam you toD. Goodhue,our Newsletter Jr. ‘73MA as the new Department Head.John I L.officially Pauly ‘64 started on 21 January 2018. It’s a true honorAndrew – F. andGori ‘68somewhat & Diane (Mccobb) daunting Gori ‘69 – to follow in the footstepsRoy D. Perdue of Farshid ‘73 Hajir, who now serves as ViceXiangdong Provost Gu of ‘06MS,’12MS,’14Ph.D. Academic Affairs and did a fantastic jobLaura in Pieczhis 3 ‘85 years as Head. I take over a department that’sGuardian risen Life tremendously Insurance in stature since I came to UMassJoan in (Magistri) 1987. PierceWe’ve ‘67 made some exceptional hires Barbaraand improved Hamkalo ‘69Ph.D. our graduate and undergraduate programs.Robert OurPiziak graduates ‘66MA,’69Ph.D. have gone& Veronica on (Kelly) Piziak Keith D. Hartt ‘83,’87MS,’93Ph.D. & Ann Wiedie ‘89,’91MS,’95Ph.D. ‘63,’65MS,’70Ph.D. to do outstandingDavid things. A. Hastings We’re ‘67,’72MA,’77Ph.D. very proud of our alumni. M. Amin Plaisted ‘82 Donald E. Hastings ‘59 Marie (Coveney) Poirier ‘64 A particular area Dominicof growth Y. Herard is our ‘01 number of undergraduate majors, whichRobert Pollackcontinually ‘54 & Lynne exceeds (Tuttle) expectations.Pollack ‘55 More and more of our incoming studentsJoseph W. recognize Higgins % & the Melanie benefits S. Higgins of majoring in math. KatherineWe have (Donner)almost Porter1000 ‘74majors in 7 areas: Actuarial Science, Applied Math, Computing,Neil B. Hindman Pure ‘67MA Math, & Audrey Statistics, (Prentiss) Hindman Teaching ‘70MS,’73Ph.D. and an IndividualStuart D. Rachlin concentration. ‘84 Mathematics is also an essential part of any 21st centuryThomas education,E. Howes ‘61 & asLesley over (Payzant) 15,000 Howes UMass ‘62 students takeRonald our classes R. Rainka each ‘63 year. Youping Huang ‘85MS Barry W. Randall ‘86 Gerald L. Janowitz ‘86 Adam B. Rattiner ‘96 Thanks to the hardMizan work R. Khan of ‘90Ph.D.our search committee, our tenure track positionRobert R. inReitano Math ‘72MA Biology was filled by our top candidate: Assistant ProfessorAlvin Brian T. Kho Van ‘94,’96MS,’00Ph.D. Koten is an expert in applied probabilityCathleen and numerical Riley ‘66 analysis, performing computer simulations of molecularJason Killam systems & Beatrice with Killam applications in biology, chemistrySteven and E. Robinson materials ‘83Ph.D. science. & Claire We (Briana) also Robinson had a very ‘73 successful year in hiring 8 newSuzanne outstanding Knapp ‘51 Visiting Assistant Professors: SiddhantJosephine Agrawal (Sears), RodriguezPanagiota ‘89MS Birmpa, Noriyuki Hamada, Kuan-Wen Lai, JonathanLeo R. Korn ‘77,’81MSSimone, Zahra Sinaei, Zheni Utic and JiayuNorman Zhai K.. OurRoth ‘71Ph.D. new Marshall & Deborah RothStone ‘68 VAP, Laura Colmenarejo Mark N. Kosmo ‘77 William H. Sabean ‘80 Hernando, will joinDeborah us in(Parent) Spring Krau 2019. ‘68 Gerard J. Sarnie ‘75,’78MBA Vicki (Birckholtz) Kuziak ‘76 Schwab Fund for Charitable Giving Our Newsletter, andMarilyn the (Galuska) on-line Lacerte Faculty ‘71 News Briefs at www.math.umass.edu,Douglas J. Shaffer provide ‘82MBA an opportunity& Leigh (Callahan) to Shaffer highlight ‘80,’82MS some of the outstanding workDenis F.of Lankowski our faculty ‘76,’84MA,’84MS in pushing the envelope of knowledgeYannan in Shen mathematics ‘09MS,’12Ph.D. and statistics each year: Assistant Professor Nestor LorraineGuillen Lavallee spoke ‘55MS at the Austin workshop “GerrymanderingMarquerite Steals Shepard-Diciaccio Elections: Learn how It’s Done and How to Marguerite (Brown) Lawton ‘54 Ann (Mercik) Sieben ‘75 Stop It,” and was partMark R.of Leeper a panel ‘72 & on Evelyn the (Chimelis) topic including Leeper ‘72 US RepresentativeSimons Jim Foundation McGovern this year; Associate Professor Paul Hacking was invitedJohn P.to Letourneau lecture ‘74at &the Marcia 2018 (Roszkiewicz) International Letourneau Congress ‘74 of Mathematicians;Walter S. Sizer ‘72MA Associate Professor Alexei Oblomkov was awarded a SimonsRachel Fellowship; (Michelson) Professors Levy ‘53 & Donald Markos M. Levy Katsoulakis and LucJonathan Rey-Bellet B. Skinner received ‘70Ph.D. a major Air Force grant to develop performance guaranteesDonald F. Liebin predictive ‘67Ph.D. & Barbara modeling; (Taddeo) Professor Lieb ‘67MA Andrea NahmodHoward R. was Smith part ‘75 of a feature honoring women in the Notices of the AMS; and UniversityChandler Lincoln Distinguished III ‘72,’78MS,’18MS Professor Panos KevrekidisEric published T. Sondergeld 4 papers‘84 in the Nature family of journals. Xinyuan Liu ‘18 David L. Stenson ‘68MA,’72Ph.D. & Ellen (Shipley) Stenson Michael C. Lyle ‘73 ‘69MA,’76Ph.D. nd Our Department Carolynhosted (Doucette) 3 conferences MacArthur this ‘72 past year: Associate ProfessorPaul V. Anna Storey ‘77 Liu was among the organizers of the 32 New England StatisticalDouglas Symposium R. Malloy bringing‘73 together nearly 250 statisticiansMary to (Hopkinson) discuss emerging Sweet ‘89 & Paulissues A. Sweet, in April Jr. 2018; Professor Andrea NahmodBrad helped Marcus organize ‘75 & Shelley Women (Sack) Marcus in Partial ‘76 Differential EquationsRichard in W. March Tabor ‘95MS 2018; and Associate Professor Hongkun Zhang co-organizedClifford Mathematical D. Martin ‘67 Physics Perspective of Billards and DominoesRobert M. Tardiff celebrating ‘72MA,’75Ph.D. the 70& thCindy birthdays Tardiff of Pavel Bleher and Leonid BunimovichGerald in F. September May ‘69 2017. Susan (McNamara) Teich ‘82 & Donald L. Teich Edward A. Maybury, Sr. ‘61 Vanguard Charitable Endowment Program John W. McAlister ‘88 Peng Wang ‘15Ph.D. & Yuanyuan Chen ‘14MS UMass Amherst undergraduatesJohn J. McColgan ‘07 Jonah Chaban, Artem Vysogorets, andNorma Jimmy (Bloem) HwangWenkalman worked ‘67 as a team, led by Assistant Professor MatthewJohn Dobson J. McDonough, to produce‘88 the top-scoring project amongMark 7 competing R. West ‘77 teams at the first ever Student Competition Using Modeling (SCUDEM)William H. McLoughlin in Fall ‘69MED 2017. & Three Patricia (Bik)more McLoughlin SCUDEM ‘64 teamsCarolyn led by(Levine) Dobson White also‘90 did very well in Spring 2018, receiving meritoriousHerbert mention P. Mehlhorn, and Jr. ‘83 outstanding mention. Jeffrey L. Whitney ‘90 & Tobi (Goldstein) Whitney ‘90 Dale A. Melikan ‘61 Gerald C. Wickham ‘60MA We are very sad toSteven have A. lostMonahan an important & Geni Monahan member of our faculty, RichardEdward S. F. Ellis Wolff, ‘74MA,’77Ph.D.who passed away& Jane Liebman in July ‘73MA 2018. Richard joined George A. Morin, Jr. ‘58 John C. Yagodzinski ‘71 the department inRobert 1975, A. O’Connelland also ‘00MS taught classes in Judaism and the TorahEllen as(Cloran) an adjunct Zoltoski ‘68 professor of Judaic and Near Eastern Studies. He was an internationally regarded expert in probability and large deviation theory, who also cared very much about the well-being of his students and colleagues, organizing sessions to relieve stress both inside and outside of the classroom. Richard will be truly missed. 2019-2020 Volume 35 23 We are also sorry to report the retirement of two important members of our faculty, Michael Lavine and Bill Meeks, in May 2018. Professor Lavine, a well-respected Bayesian statistician and a leader in our statistics group, had been a department member since 2008. Professor Meeks held the prestigious George David Birkhoff chair since joining the department in 1986; he is a world-renowned differential geometer and topologist, with a distinguished reputation in the area of minimal surfaces. The support of our alumni and friends is invaluable to us. We want to know how you are doing. Please send us your news, or stop in for a visit. – Nathaniel Whitaker DEPARTMENT OF MATHEMATICS & STATISTICS 2018 Volume 33 3 3 Non-Profit Org. U.S. Postage PAID Amherst, MA Permit No. 2 Department of Mathematics and Statistics University of Massachusetts Amherst 710 North Pleasant Street Amherst, MA 01003-9305 FRANZ PEDIT EXPLAINS THE PICTURES The surfaces shown are stationary solutions to the elliptic variational problem of minimizing the elastic membrane energy with a conformal (stretching) constraint. The classification of the minimizers and, more generally, the stationary solutions, among sur- faces of finite topology is an open question which has been answered only for surfaces of genus zero and one. The higher genus case remains elusive, but inroads have been made, as can be seen in the Lawson surface examples of higher genus. The mathematical theory behind those images involves a combination of non-linear elliptic analysis, integrable systems, non-abelian Hodge theory over curves, and loop Grassmannians. The images are based on long term collaborative theoretical work with Dr. Lynn Heller, Dr. Sebastian Heller (Hannover University), Prof. Josef Dorfmeister (TU-Munich), and Dr. Nicholas Schmitt (TU-Berlin), who also carried out extensive mathematical experiments and produced all the images using his proprietary XLab Software Suite. PUZZLE FUN Vivien Ripoli from Solving Fun ( https://solving-fun.com/ ) created the puzzle below for a departmental tea. To solve it, you may need to visit the department website to identify people; the boldfaced words are hints. If you get stuck, another hint is on page 2. RISING RESEARCHER AWARD Commonwealth Honors College student Shelby Cox ’18 is a Mathematics & Statistics and Linguistics double major who has a track record of winning awards that reflect her superb academic performance and leadership abilities in the field of mathematics and statistics. Along with establishing and serving as President of the UMass chapter of the Association for Women in Mathematics, Cox has received two Outstanding Academic Achievement Awards from the Department of Mathematics and Statistics as well as the 2017 William F. Field Alumni Scholar Award, which recognizes and honors third-year students for their academic achievements. Shelby won a prestigious National Science Foundation graduate research fellowship to pursue a PhD in pure mathematics this fall at the University of Michigan. Cox’s research accomplishments began when she participated in a summer 2016 National Science Foundation Research Experience for Undergraduates (NSF/REU) at the University of Maryland. The project concerned calculating the Euler characteristic of geometric objects, known as Hilbert schemes, which are mathematical structures in algebraic geometry that occur under symmetry. The Euler characteristic is a rough measure of the topology, or shape, of an object. The heart of Cox’s achievement was to reduce these calculations to previous known calculations that are more mathematically manageable. Cox and her collaborator gave a talk and also presented a poster on their work in January 2017 at the Joint Mathematics Meetings – the largest gathering of mathematicians in the United States and the largest annual meeting of mathematicians in the world. According to Associate Professor Eric Sommers, her advisor and teacher, “Shelby’s superb performance in research and departmental coursework, as well as her role in establishing and leading the UMass chapter of the Association for Women in Mathematics, makes her deserving of the Rising Researcher award.” Cox acknowledged just how much what it means to be a scientist has changed—but that the principles of science have remained the same: As we move on to new adventures as educators, actuaries, data scientists, software engineers and researchers, we probably won't have to remember the pigeonhole principle or the first 10 digits of π, but we will continue to solve problems. Article/photo credit: Office of News and Media Relations