2018 Leroy P. Steele Prizes
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COMBINATORIAL Bn-ANALOGUES of SCHUBERT POLYNOMIALS 0
TRANSACTIONS OF THE AMERICAN MATHEMATICAL SOCIETY Volume 348, Number 9, September 1996 COMBINATORIAL Bn-ANALOGUES OF SCHUBERT POLYNOMIALS SERGEY FOMIN AND ANATOL N. KIRILLOV Abstract. Combinatorial Bn-analogues of Schubert polynomials and corre- sponding symmetric functions are constructed and studied. The development is based on an exponential solution of the type B Yang-Baxter equation that involves the nilCoxeter algebra of the hyperoctahedral group. 0. Introduction This paper is devoted to the problem of constructing type B analogues of the Schubert polynomials of Lascoux and Sch¨utzenberger (see, e.g., [L2], [M] and the literature therein). We begin with reviewing the basic properties of the type A polynomials, stating them in a form that would allow subsequent generalizations to other types. Let W = Wn be the Coxeter group of type An with generators s1, ... ,sn (that is, the symmetric group Sn+1). Let x1, x2, ... be formal variables. Then W naturally acts on the polynomial ring C[x1,...,xn+1] by permuting the variables. Let IW denote the ideal generated by homogeneous non-constant W -symmetric polynomials. By a classical result [Bo], the cohomology ring H(F ) of the flag variety of type A can be canonically identified with the quotient C[x1,...,xn+1]/IW .This ring is graded by the degree and has a distinguished linear basis of homogeneous cosets Xw modulo IW , labelled by the elements w of the group. Let us state for the record that, for an element w W of length l(w), ∈ (0) Xw is a homogeneous polynomial of degree l(w); X1=1; the latter condition signifies proper normalization. -
Proofs from the BOOK.Pdf
Martin Aigner Günter M. Ziegler Proofs from THE BOOK Fourth Edition Martin Aigner Günter M. Ziegler Proofs from THE BOOK Fourth Edition Including Illustrations by Karl H. Hofmann 123 Prof. Dr. Martin Aigner Prof.GünterM.Ziegler FB Mathematik und Informatik Institut für Mathematik, MA 6-2 Freie Universität Berlin Technische Universität Berlin Arnimallee 3 Straße des 17. Juni 136 14195 Berlin 10623 Berlin Deutschland Deutschland [email protected] [email protected] ISBN 978-3-642-00855-9 e-ISBN 978-3-642-00856-6 DOI 10.1007/978-3-642-00856-6 Springer Heidelberg Dordrecht London New York c Springer-Verlag Berlin Heidelberg 2010 This work is subject to copyright. All rights are reserved, whether the whole or part of the material is concerned, specifically the rights of translation, reprinting, reuse of illustrations, recitation, broadcasting, reproduction on microfilm or in any other way, and storage in data banks. Duplication of this publication or parts thereof is permitted only under the provisions of the German Copyright Law of September 9, 1965, in its current version, and permission for use must always be obtained from Springer. Violations are liable to prosecution under the German Copyright Law. The use of general descriptive names, registered names, trademarks, etc. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use. Cover design: deblik, Berlin Printed on acid-free paper Springer is part of Springer Science+Business Media (www.springer.com) Preface Paul Erdosliked˝ to talk aboutThe Book, in which God maintainsthe perfect proofsfor mathematical theorems, following the dictum of G. -
2010 Integral
Autumn 2010 Volume 5 Massachusetts Institute of Technology 1ntegral n e w s f r o m t h e mathematics d e p a r t m e n t a t m i t The retirement of seven of our illustrious col- leagues this year—Mike Artin, David Ben- Inside ney, Dan Kleitman, Arthur Mattuck, Is Sing- er, Dan Stroock, and Alar Toomre—marks • Faculty news 2–3 a shift to a new generation of faculty, from • Women in math 3 those who entered the field in the Sputnik era to those who never knew life without email • A minority perspective 4 and the Internet. The older generation built • Student news 4–5 the department into the academic power- house it is today—indeed they were the core • Funds for RSI and SPUR 5 of the department, its leadership and most • Retiring faculty and staff 6–7 distinguished members, during my early years at MIT. Now, as they are in the process • Alumni corner 8 of retiring, I look around and see that my con- temporaries are becoming the department’s Dear Friends, older group. Yikes! another year gone by and what a year it Other big changes are in the works. Two of Marina Chen have taken the lead in raising an was. We’re getting older, and younger, cele- our dedicated long-term administrators— endowment for them. Together with those of brating prizes and long careers, remembering Joanne Jonsson and Linda Okun—have Tim Lu ’79 and Peiti Tung ’79, their commit- our past and looking to the future. -
Exploring Topics of the Art Gallery Problem
The College of Wooster Open Works Senior Independent Study Theses 2019 Exploring Topics of the Art Gallery Problem Megan Vuich The College of Wooster, [email protected] Follow this and additional works at: https://openworks.wooster.edu/independentstudy Recommended Citation Vuich, Megan, "Exploring Topics of the Art Gallery Problem" (2019). Senior Independent Study Theses. Paper 8534. This Senior Independent Study Thesis Exemplar is brought to you by Open Works, a service of The College of Wooster Libraries. It has been accepted for inclusion in Senior Independent Study Theses by an authorized administrator of Open Works. For more information, please contact [email protected]. © Copyright 2019 Megan Vuich Exploring Topics of the Art Gallery Problem Independent Study Thesis Presented in Partial Fulfillment of the Requirements for the Degree Bachelor of Arts in the Department of Mathematics and Computer Science at The College of Wooster by Megan Vuich The College of Wooster 2019 Advised by: Dr. Robert Kelvey Abstract Created in the 1970’s, the Art Gallery Problem seeks to answer the question of how many security guards are necessary to fully survey the floor plan of any building. These floor plans are modeled by polygons, with guards represented by points inside these shapes. Shortly after the creation of the problem, it was theorized that for guards whose positions were limited to the polygon’s j n k vertices, 3 guards are sufficient to watch any type of polygon, where n is the number of the polygon’s vertices. Two proofs accompanied this theorem, drawing from concepts of computational geometry and graph theory. -
Scientific Report for the Year 2000
The Erwin Schr¨odinger International Boltzmanngasse 9 ESI Institute for Mathematical Physics A-1090 Wien, Austria Scientific Report for the Year 2000 Vienna, ESI-Report 2000 March 1, 2001 Supported by Federal Ministry of Education, Science, and Culture, Austria ESI–Report 2000 ERWIN SCHRODINGER¨ INTERNATIONAL INSTITUTE OF MATHEMATICAL PHYSICS, SCIENTIFIC REPORT FOR THE YEAR 2000 ESI, Boltzmanngasse 9, A-1090 Wien, Austria March 1, 2001 Honorary President: Walter Thirring, Tel. +43-1-4277-51516. President: Jakob Yngvason: +43-1-4277-51506. [email protected] Director: Peter W. Michor: +43-1-3172047-16. [email protected] Director: Klaus Schmidt: +43-1-3172047-14. [email protected] Administration: Ulrike Fischer, Eva Kissler, Ursula Sagmeister: +43-1-3172047-12, [email protected] Computer group: Andreas Cap, Gerald Teschl, Hermann Schichl. International Scientific Advisory board: Jean-Pierre Bourguignon (IHES), Giovanni Gallavotti (Roma), Krzysztof Gawedzki (IHES), Vaughan F.R. Jones (Berkeley), Viktor Kac (MIT), Elliott Lieb (Princeton), Harald Grosse (Vienna), Harald Niederreiter (Vienna), ESI preprints are available via ‘anonymous ftp’ or ‘gopher’: FTP.ESI.AC.AT and via the URL: http://www.esi.ac.at. Table of contents General remarks . 2 Winter School in Geometry and Physics . 2 Wolfgang Pauli und die Physik des 20. Jahrhunderts . 3 Summer Session Seminar Sophus Lie . 3 PROGRAMS IN 2000 . 4 Duality, String Theory, and M-theory . 4 Confinement . 5 Representation theory . 7 Algebraic Groups, Invariant Theory, and Applications . 7 Quantum Measurement and Information . 9 CONTINUATION OF PROGRAMS FROM 1999 and earlier . 10 List of Preprints in 2000 . 13 List of seminars and colloquia outside of conferences . -
Paul Erdős Mathematical Genius, Human (In That Order)
Paul Erdős Mathematical Genius, Human (In That Order) By Joshua Hill MATH 341-01 4 June 2004 "A Mathematician, like a painter or a poet, is a maker of patterns. If his patterns are more permanent that theirs, it is because the are made with ideas... The mathematician's patterns, like the painter's or the poet's, must be beautiful; the ideas, like the colours of the words, must fit together in a harmonious way. Beauty is the first test: there is no permanent place in the world for ugly mathematics." --G.H. Hardy "Why are numbers beautiful? It's like asking why is Beethoven's Ninth Symphony beautiful. If you don't see why, someone can't tell you. I know numbers are beautiful. If they aren't beautiful, nothing is." -- Paul Erdős "One of the first people I met in Princeton was Paul Erdős. He was 26 years old at the time, and had his Ph.D. for several years, and had been bouncing from one postdoctoral fellowship to another... Though I was slightly younger, I considered myself wiser in the ways of the world, and I lectured Erdős "This fellowship business is all well and good, but it can't go on for much longer -- jobs are hard to get -- you had better get on the ball and start looking for a real honest job." ... Forty years after my sermon, Erdős hasn't found it necessary to look for an "honest" job yet." -- Paul Halmos Introduction Paul Erdős (said "Air-daish") was a brilliant and prolific mathematician, who was central to the advancement of several major branches of mathematics. -
Proofs from the BOOK Third Edition Springer-Verlag Berlin Heidelberg Gmbh Martin Aigner Gunter M
Martin Aigner Gunter M. Ziegler Proofs from THE BOOK Third Edition Springer-Verlag Berlin Heidelberg GmbH Martin Aigner Gunter M. Ziegler Proofs from THE BOOK Third Edition With 250 Figures Including Illustrations by Karl H. Hofmann Springer Martin Aigner Gunter M. Ziegler Freie Universitat Berlin Technische Universitat Berlin Institut flir Mathematik II (WE2) Institut flir Mathematik, MA 6-2 Arnimallee 3 StraBe des 17. Juni 136 14195 Berlin, Germany 10623 Berlin, Germany email: [email protected] email: [email protected] Cataloging-in-Publication Data applied for A catalog record for this book is available from the Library of Congress Bibliographic information published by Die Deutsche Bibliothek Die Deutsche Bibliothek lists this publication in the Deutsche Nationalbibliografie; detailed bibliographic data is available in the Internet at http://dnb.ddb.de. Mathematics Subject Classification (2000): 00-01 (General) ISBN 978-3-662-05414-7 ISBN 978-3-662-05412-3 (eBook) DOl 10 .1007/978-3 -662-05412-3 This work is subject to copyright. All rights are reserved, whether the whole or part of the material is concerned, specifically the rights of translation, reprinting, reuse of illustrations, recitation, broadcasting, reproduction on microfilm or in any other way, and storage in data banks. Duplication of this publication or parts thereof is permitted only under the provisions of the German Copyright Law of September 9, 1965, in its current version, and permission for use must always be obtained from Springer-Verlag. Viola tions are liable for prosecution under the German Copyright Law. © Springer-Verlag Berlin Heidelberg 1998,2001,2004 Originally published by Springer-Verlag Berlin Heidelberg New York in 2004. -
The Art Gallery Theorem
Outline The players The theorem The proof from THE BOOK Variations The Art Gallery Theorem Vic Reiner, Univ. of Minnesota Monthly Math Hour at UW May 18, 2014 Vic Reiner, Univ. of Minnesota The Art Gallery Theorem Outline The players The theorem The proof from THE BOOK Variations 1 The players 2 The theorem 3 The proof from THE BOOK 4 Variations Vic Reiner, Univ. of Minnesota The Art Gallery Theorem Outline The players The theorem The proof from THE BOOK Variations Victor Klee, formerly of UW Vic Reiner, Univ. of Minnesota The Art Gallery Theorem Outline The players The theorem The proof from THE BOOK Variations Klee’s question posed to V. Chvátal Given the floor plan of a weirdly shaped art gallery having N straight sides, how many guards will we need to post, in the worst case, so that every bit of wall is visible to a guard? Can one do it with N=3 guards? Vic Reiner, Univ. of Minnesota The Art Gallery Theorem Outline The players The theorem The proof from THE BOOK Variations Klee’s question posed to V. Chvátal Given the floor plan of a weirdly shaped art gallery having N straight sides, how many guards will we need to post, in the worst case, so that every bit of wall is visible to a guard? Can one do it with N=3 guards? Vic Reiner, Univ. of Minnesota The Art Gallery Theorem Outline The players The theorem The proof from THE BOOK Variations Vasek Chvátal: Yes, I can prove that! Vic Reiner, Univ. -
Arxiv:Math/9912128V1 [Math.RA] 15 Dec 1999 Iigdiagrams
TOTAL POSITIVITY: TESTS AND PARAMETRIZATIONS SERGEY FOMIN AND ANDREI ZELEVINSKY Introduction A matrix is totally positive (resp. totally nonnegative) if all its minors are pos- itive (resp. nonnegative) real numbers. The first systematic study of these classes of matrices was undertaken in the 1930s by F. R. Gantmacher and M. G. Krein [20, 21, 22], who established their remarkable spectral properties (in particular, an n × n totally positive matrix x has n distinct positive eigenvalues). Earlier, I. J. Schoenberg [41] discovered the connection between total nonnegativity and the following variation-diminishing property: the number of sign changes in a vec- tor does not increase upon multiplying by x. Total positivity found numerous applications and was studied from many dif- ferent angles. An incomplete list includes: oscillations in mechanical systems (the original motivation in [22]), stochastic processes and approximation theory [25, 28], P´olya frequency sequences [28, 40], representation theory of the infinite symmetric group and the Edrei-Thoma theorem [13, 44], planar resistor networks [11], uni- modality and log-concavity [42], and theory of immanants [43]. Further references can be found in S. Karlin’s book [28] and in the surveys [2, 5, 38]. In this paper, we focus on the following two problems: (i) parametrizing all totally nonnegative matrices; (ii) testing a matrix for total positivity. Our interest in these problems stemmed from a surprising representation-theoretic connection between total positivity and canonical bases for quantum groups, dis- covered by G. Lusztig [33] (cf. also the surveys [31, 34]). Among other things, he extended the subject by defining totally positive and totally nonnegative elements for any reductive group. -
3.1 Prime Numbers
Chapter 3 I Number Theory 159 3.1 Prime Numbers Prime numbers serve as the basic building blocks in the multiplicative structure of the integers. As you may recall, an integer n greater than one is prime if its only positive integer multiplicative factors are 1 and n. Furthermore, every integer can be expressed as a product of primes, and this expression is unique up to the order of the primes in the product. This important insight into the multiplicative structure of the integers has become known as the fundamental theorem of arithmetic . Beneath the simplicity of the prime numbers lies a sophisticated world of insights and results that has intrigued mathematicians for centuries. By the third century b.c.e. , Greek mathematicians had defined prime numbers, as one might expect from their familiarity with the division algorithm. In Book IX of Elements [73], Euclid gives a proof of the infinitude of primes—one of the most elegant proofs in all of mathematics. Just as important as this understanding of prime numbers are the many unsolved questions about primes. For example, the Riemann hypothesis is one of the most famous open questions in all of mathematics. This claim provides an analytic formula for the number of primes less than or equal to any given natural number. A proof of the Riemann hypothesis also has financial rewards. The Clay Mathematics Institute has chosen six open questions (including the Riemann hypothesis)—a complete solution of any one would earn a $1 million prize. Working toward defining a prime number, we recall an important theorem and definition from section 2.2. -
SCIENTIFIC REPORT for the 5 YEAR PERIOD 1993–1997 INCLUDING the PREHISTORY 1991–1992 ESI, Boltzmanngasse 9, A-1090 Wien, Austria
The Erwin Schr¨odinger International Boltzmanngasse 9 ESI Institute for Mathematical Physics A-1090 Wien, Austria Scientific Report for the 5 Year Period 1993–1997 Including the Prehistory 1991–1992 Vienna, ESI-Report 1993-1997 March 5, 1998 Supported by Federal Ministry of Science and Transport, Austria http://www.esi.ac.at/ ESI–Report 1993-1997 ERWIN SCHRODINGER¨ INTERNATIONAL INSTITUTE OF MATHEMATICAL PHYSICS, SCIENTIFIC REPORT FOR THE 5 YEAR PERIOD 1993–1997 INCLUDING THE PREHISTORY 1991–1992 ESI, Boltzmanngasse 9, A-1090 Wien, Austria March 5, 1998 Table of contents THE YEAR 1991 (Paleolithicum) . 3 Report on the Workshop: Interfaces between Mathematics and Physics, 1991 . 3 THE YEAR 1992 (Neolithicum) . 9 Conference on Interfaces between Mathematics and Physics . 9 Conference ‘75 years of Radon transform’ . 9 THE YEAR 1993 (Start of history of ESI) . 11 Erwin Schr¨odinger Institute opened . 11 The Erwin Schr¨odinger Institute An Austrian Initiative for East-West-Collaboration . 11 ACTIVITIES IN 1993 . 13 Short overview . 13 Two dimensional quantum field theory . 13 Schr¨odinger Operators . 16 Differential geometry . 18 Visitors outside of specific activities . 20 THE YEAR 1994 . 21 General remarks . 21 FTP-server for POSTSCRIPT-files of ESI-preprints available . 22 Winter School in Geometry and Physics . 22 ACTIVITIES IN 1994 . 22 International Symposium in Honour of Boltzmann’s 150th Birthday . 22 Ergodicity in non-commutative algebras . 23 Mathematical relativity . 23 Quaternionic and hyper K¨ahler manifolds, . 25 Spinors, twistors and conformal invariants . 27 Gibbsian random fields . 28 CONTINUATION OF 1993 PROGRAMS . 29 Two-dimensional quantum field theory . 29 Differential Geometry . 29 Schr¨odinger Operators . -
The Yang-Baxter Equation, Symmetric Functions, and Schubert Polynomials
DISCRETE MATHEMATICS ELSEVIER Discrete Mathematics 153 (1996) 123 143 The Yang-Baxter equation, symmetric functions, and Schubert polynomials Sergey Fomin a'b'*, Anatol N. Kirillov c a Department of Mathematics, Room 2-363B, Massachusetts Institute of Technolooy, Cambridge, MA 02139, USA b Theory of Aloorithms Laboratory, SPIIRAN, Russia c Steklov Mathematical Institute, St. Petersbur9, Russia Received 31 August 1993; revised 18 February 1995 Abstract We present an approach to the theory of Schubert polynomials, corresponding symmetric functions, and their generalizations that is based on exponential solutions of the Yang-Baxter equation. In the case of the solution related to the nilCoxeter algebra of the symmetric group, we recover the Schubert polynomials of Lascoux and Schiitzenberger, and provide simplified proofs of their basic properties, along with various generalizations thereof. Our techniques make use of an explicit combinatorial interpretation of these polynomials in terms of configurations of labelled pseudo-lines. Keywords: Yang-Baxter equation; Schubert polynomials; Symmetric functions 1. Introduction The Yang-Baxter operators hi(x) satisfy the following relations (cf. [1,7]): hi(x)hj(y) = hj(y)hi(x) if li -j[ >_-2; hi(x)hi+l (x + y)hi(y) = hi+l (y)hi(x + y)hi+l(X); The role the representations of the Yang-Baxter algebra play in the theory of quantum groups [9], the theory of exactly solvable models in statistical mechanics [1], low- dimensional topology [7,27,16], the theory of special functions, and other branches of mathematics (see, e.g., the survey [5]) is well known. * Corresponding author. 0012-365X/96/$15.00 (~) 1996--Elsevier Science B.V.