Alex Eskin Curriculum Vitae
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2006 Annual Report
Contents Clay Mathematics Institute 2006 James A. Carlson Letter from the President 2 Recognizing Achievement Fields Medal Winner Terence Tao 3 Persi Diaconis Mathematics & Magic Tricks 4 Annual Meeting Clay Lectures at Cambridge University 6 Researchers, Workshops & Conferences Summary of 2006 Research Activities 8 Profile Interview with Research Fellow Ben Green 10 Davar Khoshnevisan Normal Numbers are Normal 15 Feature Article CMI—Göttingen Library Project: 16 Eugene Chislenko The Felix Klein Protocols Digitized The Klein Protokolle 18 Summer School Arithmetic Geometry at the Mathematisches Institut, Göttingen, Germany 22 Program Overview The Ross Program at Ohio State University 24 PROMYS at Boston University Institute News Awards & Honors 26 Deadlines Nominations, Proposals and Applications 32 Publications Selected Articles by Research Fellows 33 Books & Videos Activities 2007 Institute Calendar 36 2006 Another major change this year concerns the editorial board for the Clay Mathematics Institute Monograph Series, published jointly with the American Mathematical Society. Simon Donaldson and Andrew Wiles will serve as editors-in-chief, while I will serve as managing editor. Associate editors are Brian Conrad, Ingrid Daubechies, Charles Fefferman, János Kollár, Andrei Okounkov, David Morrison, Cliff Taubes, Peter Ozsváth, and Karen Smith. The Monograph Series publishes Letter from the president selected expositions of recent developments, both in emerging areas and in older subjects transformed by new insights or unifying ideas. The next volume in the series will be Ricci Flow and the Poincaré Conjecture, by John Morgan and Gang Tian. Their book will appear in the summer of 2007. In related publishing news, the Institute has had the complete record of the Göttingen seminars of Felix Klein, 1872–1912, digitized and made available on James Carlson. -
A Tour Through Mirzakhani's Work on Moduli Spaces of Riemann Surfaces
BULLETIN (New Series) OF THE AMERICAN MATHEMATICAL SOCIETY Volume 57, Number 3, July 2020, Pages 359–408 https://doi.org/10.1090/bull/1687 Article electronically published on February 3, 2020 A TOUR THROUGH MIRZAKHANI’S WORK ON MODULI SPACES OF RIEMANN SURFACES ALEX WRIGHT Abstract. We survey Mirzakhani’s work relating to Riemann surfaces, which spans about 20 papers. We target the discussion at a broad audience of non- experts. Contents 1. Introduction 359 2. Preliminaries on Teichm¨uller theory 361 3. The volume of M1,1 366 4. Integrating geometric functions over moduli space 367 5. Generalizing McShane’s identity 369 6. Computation of volumes using McShane identities 370 7. Computation of volumes using symplectic reduction 371 8. Witten’s conjecture 374 9. Counting simple closed geodesics 376 10. Random surfaces of large genus 379 11. Preliminaries on dynamics on moduli spaces 382 12. Earthquake flow 386 13. Horocyclic measures 389 14. Counting with respect to the Teichm¨uller metric 391 15. From orbits of curves to orbits in Teichm¨uller space 393 16. SL(2, R)-invariant measures and orbit closures 395 17. Classification of SL(2, R)-orbit closures 398 18. Effective counting of simple closed curves 400 19. Random walks on the mapping class group 401 Acknowledgments 402 About the author 402 References 403 1. Introduction This survey aims to be a tour through Maryam Mirzakhani’s remarkable work on Riemann surfaces, dynamics, and geometry. The star characters, all across Received by the editors May 12, 2019. 2010 Mathematics Subject Classification. Primary 32G15. c 2020 American Mathematical Society 359 License or copyright restrictions may apply to redistribution; see https://www.ams.org/journal-terms-of-use 360 ALEX WRIGHT 2 3117 4 5 12 14 16 18 19 9106 13 15 17 8 Figure 1.1. -
Interview with Andrei Okounkov “I Try Hard to Learn to See the World The
Interview with Andrei Okounkov “I try hard to learn to see the world the way physicists do” Born in Moscow in 1969, he obtained his doctorate in his native city. He is currently professor of Representation Theory at Princeton University (New Jersey). His work has led to applications in a variety of fields in both mathematics and physics. Thanks to this versatility, Okounkov was chosen as a researcher for the Sloan (2000) and Packard (2001) Foundations, and in 2004 he was awarded the prestigious European Mathematical Society Prize. This might be a very standard question, but making it is mandatory for us: How do you feel, being the winner of a Fields Medal? How were you told and what did you do at that moment? Out of a whole spectrum of thoughts that I had in the time since receiving the phone call from the President of the IMU, two are especially recurrent. First, this is a great honour and it means a great responsibility. At times, I feel overwhelmed by both. Second, I can't wait to share this recognition with my friends and collaborators. Mathematics is both a personal and collective endeavour: while ideas are born in individual heads, the exchange of ideas is just as important for progress. I was very fortunate to work with many brilliant mathematician who also became my close personal friends. This is our joint success. Your work, as far as I understand, connects several areas of mathematics. Why is this important? When this connections arise, are they a surprise, or you suspect them somehow? Any mathematical proof should involve a new ingredient, something which was not already present in the statement of the problem. -
Applications at the International Congress by Marty Golubitsky
From SIAM News, Volume 39, Number 10, December 2006 Applications at the International Congress By Marty Golubitsky Grigori Perelman’s decision to decline the Fields Medal, coupled with the speculations surrounding this decision, propelled the 2006 Fields Medals to international prominence. Stories about the medals and the award ceremony at the International Congress of Mathematicians in Madrid this summer appeared in many influential news outlets (The New York Times, BBC, ABC, . .) and even in popular magazines (The New Yorker). In Madrid, the topologist John Morgan gave an excellent account of the history of the Poincaré conjecture and the ideas of Richard Hamilton and Perelman that led to the proof that the three-dimensional conjecture is correct. As Morgan pointed out, proofs of the Poincaré con- jecture and its direct generalizations have led to four Fields Medals: to Stephen Smale (1966), William Thurston (1982), Michael Freedman (1986), and now Grigori Perelman. The 2006 ICM was held in the Palacio Municipal de Congressos, a modern convention center on the outskirts of Madrid, which easily accommodated the 3600 or so participants. The interior of the convention center has a number of intriguing views—my favorite, shown below, is from the top of the three-floor-long descending escalator. Alfio Quarteroni’s plenary lecture on cardiovascular mathematics was among the many ses- The opening ceremony included a welcome sions of interest to applied mathematicians. from Juan Carlos, King of Spain, as well as the official announcement of the prize recipients—not only the four Fields Medals but also the Nevanlinna Prize and the (newly established) Gauss Prize. -
From Rational Billiards to Dynamics on Moduli Spaces
FROM RATIONAL BILLIARDS TO DYNAMICS ON MODULI SPACES ALEX WRIGHT Abstract. This short expository note gives an elementary intro- duction to the study of dynamics on certain moduli spaces, and in particular the recent breakthrough result of Eskin, Mirzakhani, and Mohammadi. We also discuss the context and applications of this result, and connections to other areas of mathematics such as algebraic geometry, Teichm¨ullertheory, and ergodic theory on homogeneous spaces. Contents 1. Rational billiards 1 2. Translation surfaces 3 3. The GL(2; R) action 7 4. Renormalization 9 5. Eskin-Mirzakhani-Mohammadi's breakthrough 10 6. Applications of Eskin-Mirzakhani-Mohammadi's Theorem 11 7. Context from homogeneous spaces 12 8. The structure of the proof 14 9. Relation to Teichm¨ullertheory and algebraic geometry 15 10. What to read next 17 References 17 1. Rational billiards Consider a point bouncing around in a polygon. Away from the edges, the point moves at unit speed. At the edges, the point bounces according to the usual rule that angle of incidence equals angle of re- flection. If the point hits a vertex, it stops moving. The path of the point is called a billiard trajectory. The study of billiard trajectories is a basic problem in dynamical systems and arises naturally in physics. For example, consider two points of different masses moving on a interval, making elastic collisions 2 WRIGHT with each other and with the endpoints. This system can be modeled by billiard trajectories in a right angled triangle [MT02]. A rational polygon is a polygon all of whose angles are rational mul- tiples of π. -
Arxiv:2101.11672V2 [Math.AG] 3 Feb 2021 Ok Fwte [ Witten Interac of and Works Insights Geom of Symplectic Physics
INTEGRABLE HIERARCHY FOR THE RESOLVED CONIFOLD MURAD ALIM AND ARPAN SAHA Abstract. We provide a direct proof of a conjecture of Brini relating the Gromov– Witten theory of the resolved conifold to the Ablowitz–Ladik integrable hierarchy at the level of primaries. We use a functional representation of the Ablowitz–Ladik hierarchy as well as a difference equation for the Gromov–Witten potential. We express the solution of the difference equation as an analytic function which is a specialization of a Tau function put forward by Bridgeland in the study of wall- crossing phenomena of Donaldson–Thomas invariants. 1. Introduction The study of integrable structures as the underlying organizing principle of Gromov– Witten (GW) theory has been a great source of insights and interactions between various areas of mathematics such as algebraic and symplectic geometry, the study of integrable systems, and mathematical physics. The KdV integrable hierarchy for GW theory of a point was put forward in the works of Witten [Wit91] and Kontsevich [Kon92], relating the intersection theory on the Deligne–Mumford compactification of the moduli space of curves to 2d topological gravity. For P1, the relation of GW theory to the Toda integrable hierarchy was studied in [EHY95, EY94, EYY95, EHX97, Pan00]. In [Pan00], a conjectured difference equation for the GW potential implied a corresponding difference equation for Hurwitz numbers which was proved in [Oko00]. A general construction of an integrable hierarchy for a given Gromov–Witten theory was given by Dubrovin and Zhang in [DZ01], see also [Dub14] for an overview, yet explicit examples remain sparse, see also [ADK+06] for a relation between topologi- cal string theory and integrable hierarchies. -
The Quaternion
The Quaternion Volume 22: Number 1; Fall, 2007 The Newsletter of the Department of Mathematics and Statistics Just a Thought about Poincaré The R. Kent Nagle Lecture Series by Boris Shekhtman The Navier-Stokes (ordinary differential) equations are Andrei Okounkov, Grigori Perelman, Terence Tao, extensions of Newton’s laws of motion to flows of Wendelin Werner. Which of these names sounds liquids or gases. Developed by Claude-Louis Navier familiar? If you circled Perelman you are not alone. I do and George Gabriel Stokes (among others) during the not remember when so many people from different Nineteenth century, these equations are critical in walks of life asked me about a mathematician: modeling weather, air flow around planes and rockets, “Do you know the dude? What’s he done?” motions of stars in a galaxy, and many other physical “Not personally but he solved the Poincaré phenomena. Conjecture.” These equations are very difficult to solve, and the “What’s that?” Clay Institute has offered $ 1,000,000 for a tractable “He proved that a 3-dimensional, simply-connected solution as one of the seven “millennial problems” in manifold is homeomorphic to a sphere” modern mathematics. Then after a pause, “Yeah, whatever, dude. What do Fang-Hua Lin , Silver Professor of Mathematics at you think? Is he nuts?” the Courant Institute of Mathematical Sciences at NYU So who is Perelman and why is he crazy? and recipient of a Sloan fellowship, a Presidential Young Grigori “Grisha” Perelman, WJM, 40, Investigator Award, the Bochner Prize, and the Chern mathematician, lives as a recluse in St. -
THE DIMENSION of the TORELLI GROUP September 3, 2007 1
THE DIMENSION OF THE TORELLI GROUP MLADEN BESTVINA, KAI-UWE BUX, AND DAN MARGALIT September 3, 2007 Abstract. We prove that the cohomological dimension of the Torelli group for a closed connected orientable surface of genus g ≥ 2 is equal to 3g − 5. This answers a question of Mess, who proved the lower bound and settled the case of g = 2. We also find the cohomological dimension of the Johnson kernel (the subgroup of the Torelli group generated by Dehn twists about separating curves) to be 2g − 3. For g ≥ 2, we prove that the top dimensional homology of the Torelli group is infinitely generated. Finally, we give a new proof of the theorem of Mess that gives a precise description of the Torelli group in genus 2. The main tool is a new contractible complex, called the “complex of cycles”, on which the Torelli group acts. 1. Introduction Let S = Sg be a closed surface of genus g (unless specified otherwise, we take all surfaces to be connected and orientable). Let Mod(S) be the mapping class group + + of S, defined as π0(Homeo (S)), where Homeo (S) is the group of orientation preserving homeomorphisms of S. The Torelli group I(S) is the kernel of the natural action of Mod(S) on H1(S, Z). This action is symplectic—it preserves the algebraic intersection number—and it is a classical fact that Mod(S) surjects onto Sp(2g, Z). All of this information is encoded in the following short exact sequence: 1 →I(S) → Mod(S) → Sp(2g, Z) → 1. -
Andrei Okounkov [email protected]
Andrei Okounkov [email protected] Born July 26, 1969, in Moscow. Citizen of the Russian Federation and of the United States of America. Current positions: | Samuel Eilenberg Professor of Mathematics, Columbia University, 2990 Broadway, New York, NY 10027 USA | Full Professor, Center for Advanced Studies, Skolkovo Institute for Science and Technology, Nobel 3, Moscow Region, 143026 Russia | Academic Supervisor, International Laboratory of Representation Theory and Mathematical Physics, Higher School of Economics, Usacheva 6, Moscow, 119048 Russia Education: 1993 B.S. in Mathematics, Moscow State University, summa cum laude 1995 Ph.D. in Mathematics, Moscow State University Honors: Sloan Research Fellowship (2000), Packard Fellowship (2001), European Mathematical Society Prize (2004), Fields Medal (2006), Compositio Prize (2009). Member of the US National Academy of Science (2012) and of the American Academy of Arts and Sciences (2016). ICM Plenary talk (2018). Member of the Royal Swedish Academy of Sciences (2020). Service: I am a member of Executive Committee of the International Mathematics Union, the Executive Organizing Com- mittee of the 2022 International Congress of Mathematicians, and cochair of the Local Organizing Committee of the 2022 International Congress of Mathematicians. I am also member of both the Russian and the US National Com- mittees. I am a long-time supporter of the Mathematical Sciences Research Institute in Berkeley, first as a member and then chair of the Scientific Advisory Committee, and then as a member and vice-chair of the Board of Trustees. Other advisory and trustee board memberships include the Clay Mathematics Institute, Packard Foundation, Simons Center for Geometry and Physics, Hamilton Mathematics Institute, and others. -
From Rational Billiards to Dynamics on Moduli Spaces
FROM RATIONAL BILLIARDS TO DYNAMICS ON MODULI SPACES ALEX WRIGHT Abstract. This short expository note gives an elementary intro- duction to the study of dynamics on certain moduli spaces, and in particular the recent breakthrough result of Eskin, Mirzakhani, and Mohammadi. We also discuss the context and applications of this result, and connections to other areas of mathematics such as algebraic geometry, Teichm¨ullertheory, and ergodic theory on homogeneous spaces. Contents 1. Rational billiards 1 2. Translation surfaces 3 3. The GL(2; R) action 7 4. Renormalization 9 5. Eskin-Mirzakhani-Mohammadi's breakthrough 10 6. Applications of Eskin-Mirzakhani-Mohammadi's Theorem 11 7. Context from homogeneous spaces 12 8. The structure of the proof 14 9. Relation to Teichm¨ullertheory and algebraic geometry 15 10. What to read next 17 References 17 arXiv:1504.08290v2 [math.DS] 26 Jul 2015 1. Rational billiards Consider a point bouncing around in a polygon. Away from the edges, the point moves at unit speed. At the edges, the point bounces according to the usual rule that angle of incidence equals angle of re- flection. If the point hits a vertex, it stops moving. The path of the point is called a billiard trajectory. The study of billiard trajectories is a basic problem in dynamical systems and arises naturally in physics. For example, consider two points of different masses moving on a interval, making elastic collisions 2 WRIGHT with each other and with the endpoints. This system can be modeled by billiard trajectories in a right angled triangle [MT02]. A rational polygon is a polygon all of whose angles are rational mul- tiples of π. -
Mathematics People
NEWS Mathematics People Mann Receives Speh Awarded Duszenko Award Noether Lectureship Kathryn Mann of Cornell University Birgit Speh of Cornell University has has been awarded the 2019 Kamil been named the 2020 Noether Lec- Duszenko Award for her work in turer by the Association for Women topology, geometry, geometric group in Mathematics (AWM) and the AMS. theory, dynamics, and other areas She will deliver the prize lectures at of mathematics. Her work involves the 2020 Joint Mathematics Meet- actions of infinite groups on mani- ings. folds and the moduli spaces of such Speh is known for her work on the actions: character varieties, spaces of representation theory of reductive Kathryn Mann flat bundles or foliations, and spaces Birgit Speh Lie groups and its relationship to of left-invariant orders on groups. automorphic forms and the coho- Some of her work involves the relationship between the mology of arithmetic groups. Her research has explored algebraic and topological structure of diffeomorphism and connections between unitary representations, automorphic homeomorphism groups, the large-scale geometry of such forms, and the geometry of locally symmetric spaces. In groups (e.g. subgroup distortion and dynamical conse- recent work Speh has studied restrictions of representations quences of this), and rigidity phenomena for group actions, of reductive groups to noncompact reductive subgroups. often arising from some geometric structure. Mann received This work on “symmetry breaking” has led, in joint work her PhD from the University of Chicago in 2014 under with Kobayashi, to proofs of conjectures of Gross–Prasad the supervision of Benson Farb. She has held positions at for some pairs of orthogonal groups. -
Institute for Pure and Applied Mathematics, UCLA Annual Progress Report for 2017-2018 Award #1440415 July 6, 2018
Institute for Pure and Applied Mathematics, UCLA Annual Progress Report for 2017-2018 Award #1440415 July 6, 2018 TABLE OF CONTENTS EXECUTIVE SUMMARY 2 A. PARTICIPANT LIST 3 B. FINANCIAL SUPPORT LIST 3 C. INCOME AND EXPENDITURE REPORT 3 D. POSTDOCTORAL PLACEMENT LIST 4 E. INSTITUTE DIRECTORS’ MEETING REPORT 4 F. PARTICIPANT SUMMARY 8 G. POSTDOCTORAL PROGRAM SUMMARY 10 H. GRADUATE STUDENT PROGRAM SUMMARY 11 I. UNDERGRADUATE STUDENT PROGRAM SUMMARY 12 J. PROGRAM DESCRIPTION 13 K. PROGRAM CONSULTANT LIST 40 L. PUBLICATIONS LIST 43 M. INDUSTRIAL AND GOVERNMENTAL INVOLVEMENT 43 N. EXTERNAL SUPPORT 44 O. COMMITTEE MEMBERSHIP 45 IPAM Annual Report 2017-2018 Institute for Pure and Applied Mathematics, UCLA Annual Progress Report for 2017-2018 Award #1440415 July 6, 2018 EXECUTIVE SUMMARY This report covers our activities from June 11, 2017 to June 10, 2018 (which we refer to as the reporting period). The culminating retreat of the spring long program is part of this year’s report, along with the two reunion conferences, which are held the same week. This report includes the 2017 summer programs (RIPS and GRIPS). The 2018 summer programs will be included in next year’s report. IPAM held two long program in the reporting period: Complex High-Dimensional Energy Landscapes Quantitative Linear Algebra IPAM held the following workshops in the reporting period: RIPS Projects Day Mean Field Games Algorithmic Challenges in Protecting Privacy for Biomedical Data New Methods for Zimmer's Conjecture New Deep Learning Techniques IPAM typically offers two reunion conferences for each IPAM long program; the first is held a year and a half after the conclusion of the long program, and the second is held one year after the first.