Lecture Notes in Triangulation Conjecture
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Scalar Curvature and Geometrization Conjectures for 3-Manifolds
Comparison Geometry MSRI Publications Volume 30, 1997 Scalar Curvature and Geometrization Conjectures for 3-Manifolds MICHAEL T. ANDERSON Abstract. We first summarize very briefly the topology of 3-manifolds and the approach of Thurston towards their geometrization. After dis- cussing some general properties of curvature functionals on the space of metrics, we formulate and discuss three conjectures that imply Thurston’s Geometrization Conjecture for closed oriented 3-manifolds. The final two sections present evidence for the validity of these conjectures and outline an approach toward their proof. Introduction In the late seventies and early eighties Thurston proved a number of very re- markable results on the existence of geometric structures on 3-manifolds. These results provide strong support for the profound conjecture, formulated by Thur- ston, that every compact 3-manifold admits a canonical decomposition into do- mains, each of which has a canonical geometric structure. For simplicity, we state the conjecture only for closed, oriented 3-manifolds. Geometrization Conjecture [Thurston 1982]. Let M be a closed , oriented, 2 prime 3-manifold. Then there is a finite collection of disjoint, embedded tori Ti 2 in M, such that each component of the complement M r Ti admits a geometric structure, i.e., a complete, locally homogeneous RiemannianS metric. A more detailed description of the conjecture and the terminology will be given in Section 1. A complete Riemannian manifold N is locally homogeneous if the universal cover N˜ is a complete homogenous manifold, that is, if the isometry group Isom N˜ acts transitively on N˜. It follows that N is isometric to N=˜ Γ, where Γ is a discrete subgroup of Isom N˜, which acts freely and properly discontinuously on N˜. -
On the Circuit Diameter Conjecture
On the Circuit Diameter Conjecture Steffen Borgwardt1, Tamon Stephen2, and Timothy Yusun2 1 University of Colorado Denver [email protected] 2 Simon Fraser University {tamon,tyusun}@sfu.ca Abstract. From the point of view of optimization, a critical issue is relating the combina- torial diameter of a polyhedron to its number of facets f and dimension d. In the seminal paper of Klee and Walkup [KW67], the Hirsch conjecture of an upper bound of f − d was shown to be equivalent to several seemingly simpler statements, and was disproved for unbounded polyhedra through the construction of a particular 4-dimensional polyhedron U4 with 8 facets. The Hirsch bound for bounded polyhedra was only recently disproved by Santos [San12]. We consider analogous properties for a variant of the combinatorial diameter called the circuit diameter. In this variant, the walks are built from the circuit directions of the poly- hedron, which are the minimal non-trivial solutions to the system defining the polyhedron. We are able to prove that circuit variants of the so-called non-revisiting conjecture and d-step conjecture both imply the circuit analogue of the Hirsch conjecture. For the equiva- lences in [KW67], the wedge construction was a fundamental proof technique. We exhibit why it is not available in the circuit setting, and what are the implications of losing it as a tool. Further, we show the circuit analogue of the non-revisiting conjecture implies a linear bound on the circuit diameter of all unbounded polyhedra – in contrast to what is known for the combinatorial diameter. Finally, we give two proofs of a circuit version of the 4-step conjecture. -
Generalized Riemann Hypothesis Léo Agélas
Generalized Riemann Hypothesis Léo Agélas To cite this version: Léo Agélas. Generalized Riemann Hypothesis. 2019. hal-00747680v3 HAL Id: hal-00747680 https://hal.archives-ouvertes.fr/hal-00747680v3 Preprint submitted on 29 May 2019 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. Generalized Riemann Hypothesis L´eoAg´elas Department of Mathematics, IFP Energies nouvelles, 1-4, avenue de Bois-Pr´eau,F-92852 Rueil-Malmaison, France Abstract (Generalized) Riemann Hypothesis (that all non-trivial zeros of the (Dirichlet L-function) zeta function have real part one-half) is arguably the most impor- tant unsolved problem in contemporary mathematics due to its deep relation to the fundamental building blocks of the integers, the primes. The proof of the Riemann hypothesis will immediately verify a slew of dependent theorems (Borwien et al.(2008), Sabbagh(2002)). In this paper, we give a proof of Gen- eralized Riemann Hypothesis which implies the proof of Riemann Hypothesis and Goldbach's weak conjecture (also known as the odd Goldbach conjecture) one of the oldest and best-known unsolved problems in number theory. 1. Introduction The Riemann hypothesis is one of the most important conjectures in math- ematics. -
Diameter of Simplicial Complexes, a Computational Approach
University of Cantabria Master’s thesis. Masters degree in Mathematics and Computing Diameter of simplicial complexes, a computational approach Author: Advisor: Francisco Criado Gallart Francisco Santos Leal 2015-2016 This work is licensed under a Creative Commons Attribution-ShareAlike 4.0 International License. Desvarío laborioso y empobrecedor el de componer vastos libros; el de explayar en quinientas páginas una idea cuya perfecta exposición oral cabe en pocos minutos. Mejor procedimiento es simular que esos libros ya existen y ofrecer un resumen, un comentario. Borges, Ficciones Acknowledgements First, I would like to thank my advisor, professor Francisco Santos. He has been supportive years before I arrived in Santander, and even more when I arrived. Also, I want to thank professor Michael Joswig and his team in the discrete ge- ometry group of the Technical University of Berlin, for all the help and advice that they provided during my (short) visit to their department. Finally, I want to thank my friends at Cantabria, and my “disciples”: Álvaro, Ana, Beatriz, Cristina, David, Esther, Jesús, Jon, Manu, Néstor, Sara and Susana. i Diameter of simplicial complexes, a computational approach Abstract The computational complexity of the simplex method, widely used for linear program- ming, depends on the combinatorial diameter of the edge graph of a polyhedron with n facets and dimension d. Despite its popularity, little is known about the (combinatorial) diameter of polytopes, and even for simpler types of complexes. For the case of polytopes, it was conjectured by Hirsch (1957) that the diameter is smaller than (n − d), but this was disproved by Francisco Santos (2010). -
Towards the Poincaré Conjecture and the Classification of 3-Manifolds John Milnor
Towards the Poincaré Conjecture and the Classification of 3-Manifolds John Milnor he Poincaré Conjecture was posed ninety- space SO(3)/I60 . Here SO(3) is the group of rota- nine years ago and may possibly have tions of Euclidean 3-space, and I60 is the subgroup been proved in the last few months. This consisting of those rotations which carry a regu- note will be an account of some of the lar icosahedron or dodecahedron onto itself (the Tmajor results over the past hundred unique simple group of order 60). This manifold years which have paved the way towards a proof has the homology of the 3-sphere, but its funda- and towards the even more ambitious project of mental group π1(SO(3)/I60) is a perfect group of classifying all compact 3-dimensional manifolds. order 120. He concluded the discussion by asking, The final paragraph provides a brief description of again translated into modern language: the latest developments, due to Grigory Perelman. A more serious discussion of Perelman’s work If a closed 3-dimensional manifold has will be provided in a subsequent note by Michael trivial fundamental group, must it be Anderson. homeomorphic to the 3-sphere? The conjecture that this is indeed the case has Poincaré’s Question come to be known as the Poincaré Conjecture. It At the very beginning of the twentieth century, has turned out to be an extraordinarily difficult Henri Poincaré (1854–1912) made an unwise claim, question, much harder than the corresponding which can be stated in modern language as follows: question in dimension five or more,2 and is a If a closed 3-dimensional manifold has key stumbling block in the effort to classify the homology of the sphere S3 , then it 3-dimensional manifolds. -
PIECEWISE LINEAR TOPOLOGY Contents 1. Introduction 2 2. Basic
PIECEWISE LINEAR TOPOLOGY J. L. BRYANT Contents 1. Introduction 2 2. Basic Definitions and Terminology. 2 3. Regular Neighborhoods 9 4. General Position 16 5. Embeddings, Engulfing 19 6. Handle Theory 24 7. Isotopies, Unknotting 30 8. Approximations, Controlled Isotopies 31 9. Triangulations of Manifolds 33 References 35 1 2 J. L. BRYANT 1. Introduction The piecewise linear category offers a rich structural setting in which to study many of the problems that arise in geometric topology. The first systematic ac- counts of the subject may be found in [2] and [63]. Whitehead’s important paper [63] contains the foundation of the geometric and algebraic theory of simplicial com- plexes that we use today. More recent sources, such as [30], [50], and [66], together with [17] and [37], provide a fairly complete development of PL theory up through the early 1970’s. This chapter will present an overview of the subject, drawing heavily upon these sources as well as others with the goal of unifying various topics found there as well as in other parts of the literature. We shall try to give enough in the way of proofs to provide the reader with a flavor of some of the techniques of the subject, while deferring the more intricate details to the literature. Our discussion will generally avoid problems associated with embedding and isotopy in codimension 2. The reader is referred to [12] for a survey of results in this very important area. 2. Basic Definitions and Terminology. Simplexes. A simplex of dimension p (a p-simplex) σ is the convex closure of a n set of (p+1) geometrically independent points {v0, . -
Report on 8Th EUROPT Workshop on Advances in Continuous
8th EUROPT Workshop on Advances in Continuous Optimization Aveiro, Portugal, July 9-10, 2010 Final Report The 8th EUROPT Workshop on Advances in Continuous Optimization was hosted by the Univer- sity of Aveiro, Portugal. Workshop started with a Welcome Reception of the participants on July 8, fol- lowed by two working days, July 9 and July 10. This Workshop continued the line of the past EUROPT workshops. The first one was held in 2000 in Budapest, followed by the workshops in Rotterdam in 2001, Istanbul in 2003, Rhodes in 2004, Reykjavik in 2006, Prague in 2007, and Remagen in 2009. All these international workshops were organized by the EURO Working Group on Continuous Optimization (EUROPT; http://www.iam.metu.edu.tr/EUROPT) as a satellite meeting of the EURO Conferences. This time, the 8th EUROPT Workshop, was a satellite meeting before the EURO XXIV Conference in Lisbon, (http://www.euro2010lisbon.org/). During the 8th EUROPT Workshop, the organizational duties were distributed between a Scientific Committee, an Organizing Committee, and a Local Committee. • The Scientific Committee was composed by Marco Lopez (Chair), Universidad de Alicante; Domin- gos Cardoso, Universidade de Aveiro; Emilio Carrizosa, Universidad de Sevilla; Joaquim Judice, Uni- versidade de Coimbra; Diethard Klatte, Universitat Zurich; Olga Kostyukova, Belarusian Academy of Sciences; Marco Locatelli, Universita’ di Torino; Florian Potra, University of Maryland Baltimore County; Franz Rendl, Universitat Klagenfurt; Claudia Sagastizabal, CEPEL (Research Center for Electric Energy); Oliver Stein, Karlsruhe Institute of Technology; Georg Still, University of Twente. • The Organizing Committee was composed by Domingos Cardoso (Chair), Universidade de Aveiro; Tatiana Tchemisova (co-Chair), Universidade de Aveiro; Miguel Anjos, University of Waterloo; Edite Fernandes, Universidade do Minho; Vicente Novo, UNED (Spain); Juan Parra, Universidad Miguel Hernandez´ de Elche; Gerhard-Wilhelm Weber, Middle East Technical University. -
The Process of Student Cognition in Constructing Mathematical Conjecture
ISSN 2087-8885 E-ISSN 2407-0610 Journal on Mathematics Education Volume 9, No. 1, January 2018, pp. 15-26 THE PROCESS OF STUDENT COGNITION IN CONSTRUCTING MATHEMATICAL CONJECTURE I Wayan Puja Astawa1, I Ketut Budayasa2, Dwi Juniati2 1Ganesha University of Education, Jalan Udayana 11, Singaraja, Indonesia 2State University of Surabaya, Ketintang, Surabaya, Indonesia Email: [email protected] Abstract This research aims to describe the process of student cognition in constructing mathematical conjecture. Many researchers have studied this process but without giving a detailed explanation of how students understand the information to construct a mathematical conjecture. The researchers focus their analysis on how to construct and prove the conjecture. This article discusses the process of student cognition in constructing mathematical conjecture from the very beginning of the process. The process is studied through qualitative research involving six students from the Mathematics Education Department in the Ganesha University of Education. The process of student cognition in constructing mathematical conjecture is grouped into five different stages. The stages consist of understanding the problem, exploring the problem, formulating conjecture, justifying conjecture, and proving conjecture. In addition, details of the process of the students’ cognition in each stage are also discussed. Keywords: Process of Student Cognition, Mathematical Conjecture, qualitative research Abstrak Penelitian ini bertujuan untuk mendeskripsikan proses kognisi mahasiswa dalam mengonstruksi konjektur matematika. Beberapa peneliti mengkaji proses-proses ini tanpa menjelaskan bagaimana siswa memahami informasi untuk mengonstruksi konjektur. Para peneliti dalam analisisnya menekankan bagaimana mengonstruksi dan membuktikan konjektur. Artikel ini membahas proses kognisi mahasiswa dalam mengonstruksi konjektur matematika dari tahap paling awal. -
History of Mathematics
History of Mathematics James Tattersall, Providence College (Chair) Janet Beery, University of Redlands Robert E. Bradley, Adelphi University V. Frederick Rickey, United States Military Academy Lawrence Shirley, Towson University Introduction. There are many excellent reasons to study the history of mathematics. It helps students develop a deeper understanding of the mathematics they have already studied by seeing how it was developed over time and in various places. It encourages creative and flexible thinking by allowing students to see historical evidence that there are different and perfectly valid ways to view concepts and to carry out computations. Ideally, a History of Mathematics course should be a part of every mathematics major program. A course taught at the sophomore-level allows mathematics students to see the great wealth of mathematics that lies before them and encourages them to continue studying the subject. A one- or two-semester course taught at the senior level can dig deeper into the history of mathematics, incorporating many ideas from the 19th and 20th centuries that could only be approached with difficulty by less prepared students. Such a senior-level course might be a capstone experience taught in a seminar format. It would be wonderful for students, especially those planning to become middle school or high school mathematics teachers, to have the opportunity to take advantage of both options. We also encourage History of Mathematics courses taught to entering students interested in mathematics, perhaps as First Year or Honors Seminars; to general education students at any level; and to junior and senior mathematics majors and minors. Ideally, mathematics history would be incorporated seamlessly into all courses in the undergraduate mathematics curriculum in addition to being addressed in a few courses of the type we have listed. -
Arxiv:Math/0403494V1
ONE-POINT SUSPENSIONS AND WREATH PRODUCTS OF POLYTOPES AND SPHERES MICHAEL JOSWIG AND FRANK H. LUTZ Abstract. It is known that the suspension of a simplicial complex can be realized with only one additional point. Suitable iterations of this construction generate highly symmetric simplicial complexes with various interesting combinatorial and topological properties. In particular, infinitely many non-PL spheres as well as contractible simplicial complexes with a vertex-transitive group of automorphisms can be obtained in this way. 1. Introduction McMullen [34] constructed projectively unique convex polytopes as the joint convex hulls of polytopes in mutually skew affine subspaces which are attached to the vertices of yet another polytope. It is immediate that if the polytopes attached are pairwise isomorphic one can obtain polytopes with a large group of automorphisms. In fact, if the polytopes attached are simplices, then the resulting polytope can be obtained by successive wedging (or rather its dual operation). This dual wedge, first introduced and exploited by Adler and Dantzig [1] in 1974 for the study of the Hirsch conjecture of linear programming, is essentially the same as the one-point suspension in combinatorial topology. It is striking that this simple construction makes several appearances in the literature, while it seems that never before it had been the focus of research for its own sake. The purpose of this paper is to collect what is known (for the polytopal as well as the combinatorial constructions) and to fill in several gaps, most notably by introducing wreath products of simplicial complexes. In particular, we give a detailed analysis of wreath products in order to provide explicit descriptions of highly symmetric polytopes which previously had been implicit in McMullen’s construction. -
Program of the Sessions San Diego, California, January 9–12, 2013
Program of the Sessions San Diego, California, January 9–12, 2013 AMS Short Course on Random Matrices, Part Monday, January 7 I MAA Short Course on Conceptual Climate Models, Part I 9:00 AM –3:45PM Room 4, Upper Level, San Diego Convention Center 8:30 AM –5:30PM Room 5B, Upper Level, San Diego Convention Center Organizer: Van Vu,YaleUniversity Organizers: Esther Widiasih,University of Arizona 8:00AM Registration outside Room 5A, SDCC Mary Lou Zeeman,Bowdoin upper level. College 9:00AM Random Matrices: The Universality James Walsh, Oberlin (5) phenomenon for Wigner ensemble. College Preliminary report. 7:30AM Registration outside Room 5A, SDCC Terence Tao, University of California Los upper level. Angles 8:30AM Zero-dimensional energy balance models. 10:45AM Universality of random matrices and (1) Hans Kaper, Georgetown University (6) Dyson Brownian Motion. Preliminary 10:30AM Hands-on Session: Dynamics of energy report. (2) balance models, I. Laszlo Erdos, LMU, Munich Anna Barry*, Institute for Math and Its Applications, and Samantha 2:30PM Free probability and Random matrices. Oestreicher*, University of Minnesota (7) Preliminary report. Alice Guionnet, Massachusetts Institute 2:00PM One-dimensional energy balance models. of Technology (3) Hans Kaper, Georgetown University 4:00PM Hands-on Session: Dynamics of energy NSF-EHR Grant Proposal Writing Workshop (4) balance models, II. Anna Barry*, Institute for Math and Its Applications, and Samantha 3:00 PM –6:00PM Marina Ballroom Oestreicher*, University of Minnesota F, 3rd Floor, Marriott The time limit for each AMS contributed paper in the sessions meeting will be found in Volume 34, Issue 1 of Abstracts is ten minutes. -
Triangulations of 3-Manifolds with Essential Edges
TRIANGULATIONS OF 3–MANIFOLDS WITH ESSENTIAL EDGES CRAIG D. HODGSON, J. HYAM RUBINSTEIN, HENRY SEGERMAN AND STEPHAN TILLMANN Dedicated to Michel Boileau for his many contributions and leadership in low dimensional topology. ABSTRACT. We define essential and strongly essential triangulations of 3–manifolds, and give four constructions using different tools (Heegaard splittings, hierarchies of Haken 3–manifolds, Epstein-Penner decompositions, and cut loci of Riemannian manifolds) to obtain triangulations with these properties under various hypotheses on the topology or geometry of the manifold. We also show that a semi-angle structure is a sufficient condition for a triangulation of a 3–manifold to be essential, and a strict angle structure is a sufficient condition for a triangulation to be strongly essential. Moreover, algorithms to test whether a triangulation of a 3–manifold is essential or strongly essential are given. 1. INTRODUCTION Finding combinatorial and topological properties of geometric triangulations of hyper- bolic 3–manifolds gives information which is useful for the reverse process—for exam- ple, solving Thurston’s gluing equations to construct an explicit hyperbolic metric from an ideal triangulation. Moreover, suitable properties of a triangulation can be used to de- duce facts about the variety of representations of the fundamental group of the underlying 3-manifold into PSL(2;C). See for example [32]. In this paper, we focus on one-vertex triangulations of closed manifolds and ideal trian- gulations of the interiors of compact manifolds with boundary. Two important properties of these triangulations are introduced. For one-vertex triangulations in the closed case, the first property is that no edge loop is null-homotopic and the second is that no two edge loops are homotopic, keeping the vertex fixed.