Problems on Low-Dimensional Topology, 2018
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An Introduction to Topology the Classification Theorem for Surfaces by E
An Introduction to Topology An Introduction to Topology The Classification theorem for Surfaces By E. C. Zeeman Introduction. The classification theorem is a beautiful example of geometric topology. Although it was discovered in the last century*, yet it manages to convey the spirit of present day research. The proof that we give here is elementary, and its is hoped more intuitive than that found in most textbooks, but in none the less rigorous. It is designed for readers who have never done any topology before. It is the sort of mathematics that could be taught in schools both to foster geometric intuition, and to counteract the present day alarming tendency to drop geometry. It is profound, and yet preserves a sense of fun. In Appendix 1 we explain how a deeper result can be proved if one has available the more sophisticated tools of analytic topology and algebraic topology. Examples. Before starting the theorem let us look at a few examples of surfaces. In any branch of mathematics it is always a good thing to start with examples, because they are the source of our intuition. All the following pictures are of surfaces in 3-dimensions. In example 1 by the word “sphere” we mean just the surface of the sphere, and not the inside. In fact in all the examples we mean just the surface and not the solid inside. 1. Sphere. 2. Torus (or inner tube). 3. Knotted torus. 4. Sphere with knotted torus bored through it. * Zeeman wrote this article in the mid-twentieth century. 1 An Introduction to Topology 5. -
Area, Volume and Surface Area
The Improving Mathematics Education in Schools (TIMES) Project MEASUREMENT AND GEOMETRY Module 11 AREA, VOLUME AND SURFACE AREA A guide for teachers - Years 8–10 June 2011 YEARS 810 Area, Volume and Surface Area (Measurement and Geometry: Module 11) For teachers of Primary and Secondary Mathematics 510 Cover design, Layout design and Typesetting by Claire Ho The Improving Mathematics Education in Schools (TIMES) Project 2009‑2011 was funded by the Australian Government Department of Education, Employment and Workplace Relations. The views expressed here are those of the author and do not necessarily represent the views of the Australian Government Department of Education, Employment and Workplace Relations. © The University of Melbourne on behalf of the international Centre of Excellence for Education in Mathematics (ICE‑EM), the education division of the Australian Mathematical Sciences Institute (AMSI), 2010 (except where otherwise indicated). This work is licensed under the Creative Commons Attribution‑NonCommercial‑NoDerivs 3.0 Unported License. http://creativecommons.org/licenses/by‑nc‑nd/3.0/ The Improving Mathematics Education in Schools (TIMES) Project MEASUREMENT AND GEOMETRY Module 11 AREA, VOLUME AND SURFACE AREA A guide for teachers - Years 8–10 June 2011 Peter Brown Michael Evans David Hunt Janine McIntosh Bill Pender Jacqui Ramagge YEARS 810 {4} A guide for teachers AREA, VOLUME AND SURFACE AREA ASSUMED KNOWLEDGE • Knowledge of the areas of rectangles, triangles, circles and composite figures. • The definitions of a parallelogram and a rhombus. • Familiarity with the basic properties of parallel lines. • Familiarity with the volume of a rectangular prism. • Basic knowledge of congruence and similarity. • Since some formulas will be involved, the students will need some experience with substitution and also with the distributive law. -
Geometric Methods in Heegaard Theory
GEOMETRIC METHODS IN HEEGAARD THEORY TOBIAS HOLCK COLDING, DAVID GABAI, AND DANIEL KETOVER Abstract. We survey some recent geometric methods for studying Heegaard splittings of 3-manifolds 0. Introduction A Heegaard splitting of a closed orientable 3-manifold M is a decomposition of M into two handlebodies H0 and H1 which intersect exactly along their boundaries. This way of thinking about 3-manifolds (though in a slightly different form) was discovered by Poul Heegaard in his forward looking 1898 Ph. D. thesis [Hee1]. He wanted to classify 3-manifolds via their diagrams. In his words1: Vi vende tilbage til Diagrammet. Den Opgave, der burde løses, var at reducere det til en Normalform; det er ikke lykkedes mig at finde en saadan, men jeg skal dog fremsætte nogle Bemærkninger angaaende Opgavens Løsning. \We will return to the diagram. The problem that ought to be solved was to reduce it to the normal form; I have not succeeded in finding such a way but I shall express some remarks about the problem's solution." For more details and a historical overview see [Go], and [Zie]. See also the French translation [Hee2], the English translation [Mun] and the partial English translation [Prz]. See also the encyclopedia article of Dehn and Heegaard [DH]. In his 1932 ICM address in Zurich [Ax], J. W. Alexander asked to determine in how many essentially different ways a canonical region can be traced in a manifold or in modern language how many different isotopy classes are there for splittings of a given genus. He viewed this as a step towards Heegaard's program. -
Riemann Surfaces
RIEMANN SURFACES AARON LANDESMAN CONTENTS 1. Introduction 2 2. Maps of Riemann Surfaces 4 2.1. Defining the maps 4 2.2. The multiplicity of a map 4 2.3. Ramification Loci of maps 6 2.4. Applications 6 3. Properness 9 3.1. Definition of properness 9 3.2. Basic properties of proper morphisms 9 3.3. Constancy of degree of a map 10 4. Examples of Proper Maps of Riemann Surfaces 13 5. Riemann-Hurwitz 15 5.1. Statement of Riemann-Hurwitz 15 5.2. Applications 15 6. Automorphisms of Riemann Surfaces of genus ≥ 2 18 6.1. Statement of the bound 18 6.2. Proving the bound 18 6.3. We rule out g(Y) > 1 20 6.4. We rule out g(Y) = 1 20 6.5. We rule out g(Y) = 0, n ≥ 5 20 6.6. We rule out g(Y) = 0, n = 4 20 6.7. We rule out g(C0) = 0, n = 3 20 6.8. 21 7. Automorphisms in low genus 0 and 1 22 7.1. Genus 0 22 7.2. Genus 1 22 7.3. Example in Genus 3 23 Appendix A. Proof of Riemann Hurwitz 25 Appendix B. Quotients of Riemann surfaces by automorphisms 29 References 31 1 2 AARON LANDESMAN 1. INTRODUCTION In this course, we’ll discuss the theory of Riemann surfaces. Rie- mann surfaces are a beautiful breeding ground for ideas from many areas of math. In this way they connect seemingly disjoint fields, and also allow one to use tools from different areas of math to study them. -
Visual Cortex: Looking Into a Klein Bottle Nicholas V
776 Dispatch Visual cortex: Looking into a Klein bottle Nicholas V. Swindale Arguments based on mathematical topology may help work which suggested that many properties of visual cortex in understanding the organization of topographic maps organization might be a consequence of mapping a five- in the cerebral cortex. dimensional stimulus space onto a two-dimensional surface as continuously as possible. Recent experimental results, Address: Department of Ophthalmology, University of British Columbia, 2550 Willow Street, Vancouver, V5Z 3N9, British which I shall discuss here, add to this complexity because Columbia, Canada. they show that a stimulus attribute not considered in the theoretical studies — direction of motion — is also syst- Current Biology 1996, Vol 6 No 7:776–779 ematically mapped on the surface of the cortex. This adds © Current Biology Ltd ISSN 0960-9822 to the evidence that continuity is an important, though not overriding, organizational principle in the cortex. I shall The English neurologist Hughlings Jackson inferred the also discuss a demonstration that certain receptive-field presence of a topographic map of the body musculature in properties, which may be indirectly related to direction the cerebral cortex more than a century ago, from his selectivity, can be represented as positions in a non- observations of the orderly progressions of seizure activity Euclidian space with a topology known to mathematicians across the body during epilepsy. Topographic maps of one as a Klein bottle. First, however, it is appropriate to cons- kind or another are now known to be a ubiquitous feature ider the experimental data. of cortical organization, at least in the primary sensory and motor areas. -
Motion on a Torus Kirk T
Motion on a Torus Kirk T. McDonald Joseph Henry Laboratories, Princeton University, Princeton, NJ 08544 (October 21, 2000) 1 Problem Find the frequency of small oscillations about uniform circular motion of a point mass that is constrained to move on the surface of a torus (donut) of major radius a and minor radius b whose axis is vertical. 2 Solution 2.1 Attempt at a Quick Solution Circular orbits are possible in both horizontal and vertical planes, but in the presence of gravity, motion in vertical orbits will be at a nonuniform velocity. Hence, we restrict our attention to orbits in horizontal planes. We use a cylindrical coordinate system (r; θ; z), with the origin at the center of the torus and the z axis vertically upwards, as shown below. 1 A point on the surface of the torus can also be described by two angular coordinates, one of which is the azimuth θ in the cylindrical coordinate system. The other angle we define as Á measured with respect to the plane z = 0 in a vertical plane that contains the point as well as the axis, as also shown in the figure above. We seek motion at constant angular velocity Ω about the z axis, which suggests that we consider a frame that rotates with this angular velocity. In this frame, the particle (whose mass we take to be unity) is at rest at angle Á0, and is subject to the downward force of 2 gravity g and the outward centrifugal force Ω (a + b cos Á0), as shown in the figure below. -
Surface Topology
2 Surface topology 2.1 Classification of surfaces In this second introductory chapter, we change direction completely. We dis- cuss the topological classification of surfaces, and outline one approach to a proof. Our treatment here is almost entirely informal; we do not even define precisely what we mean by a ‘surface’. (Definitions will be found in the following chapter.) However, with the aid of some more sophisticated technical language, it not too hard to turn our informal account into a precise proof. The reasons for including this material here are, first, that it gives a counterweight to the previous chapter: the two together illustrate two themes—complex analysis and topology—which run through the study of Riemann surfaces. And, second, that we are able to introduce some more advanced ideas that will be taken up later in the book. The statement of the classification of closed surfaces is probably well known to many readers. We write down two families of surfaces g, h for integers g ≥ 0, h ≥ 1. 2 2 The surface 0 is the 2-sphere S . The surface 1 is the 2-torus T .For g ≥ 2, we define the surface g by taking the ‘connected sum’ of g copies of the torus. In general, if X and Y are (connected) surfaces, the connected sum XY is a surface constructed as follows (Figure 2.1). We choose small discs DX in X and DY in Y and cut them out to get a pair of ‘surfaces-with- boundaries’, coresponding to the circle boundaries of DX and DY. -
Heegaard Splittings of Knot Exteriors 1 Introduction
Geometry & Topology Monographs 12 (2007) 191–232 191 arXiv version: fonts, pagination and layout may vary from GTM published version Heegaard splittings of knot exteriors YOAV MORIAH The goal of this paper is to offer a comprehensive exposition of the current knowledge about Heegaard splittings of exteriors of knots in the 3-sphere. The exposition is done with a historical perspective as to how ideas developed and by whom. Several new notions are introduced and some facts about them are proved. In particular the concept of a 1=n-primitive meridian. It is then proved that if a knot K ⊂ S3 has a 1=n-primitive meridian; then nK = K# ··· #K n-times has a Heegaard splitting of genus nt(K) + n which has a 1-primitive meridian. That is, nK is µ-primitive. 57M25; 57M05 1 Introduction The goal of this survey paper is to sum up known results about Heegaard splittings of knot exteriors in S3 and present them with some historical perspective. Until the mid 80’s Heegaard splittings of 3–manifolds and in particular of knot exteriors were not well understood at all. Most of the interest in studying knot spaces, up until then, was directed at various knot invariants which had a distinct algebraic flavor to them. Then in 1985 the remarkable work of Vaughan Jones turned the area around and began the era of the modern knot invariants a` la the Jones polynomial and its descendants and derivatives. However at the same time there were major developments in Heegaard theory of 3–manifolds in general and knot exteriors in particular. -
The Hairy Klein Bottle
Bridges 2019 Conference Proceedings The Hairy Klein Bottle Daniel Cohen1 and Shai Gul 2 1 Dept. of Industrial Design, Holon Institute of Technology, Israel; [email protected] 2 Dept. of Applied Mathematics, Holon Institute of Technology, Israel; [email protected] Abstract In this collaborative work between a mathematician and designer we imagine a hairy Klein bottle, a fusion that explores a continuous non-vanishing vector field on a non-orientable surface. We describe the modeling process of creating a tangible, tactile sculpture designed to intrigue and invite simple understanding. Figure 1: The hairy Klein bottle which is described in this manuscript Introduction Topology is a field of mathematics that is not so interested in the exact shape of objects involved but rather in the way they are put together (see [4]). A well-known example is that, from a topological perspective a doughnut and a coffee cup are the same as both contain a single hole. Topology deals with many concepts that can be tricky to grasp without being able to see and touch a three dimensional model, and in some cases the concepts consists of more than three dimensions. Some of the most interesting objects in topology are non-orientable surfaces. Séquin [6] and Frazier & Schattschneider [1] describe an application of the Möbius strip, a non-orientable surface. Séquin [5] describes the Klein bottle, another non-orientable object that "lives" in four dimensions from a mathematical point of view. This particular manuscript was inspired by the hairy ball theorem which has the remarkable implication in (algebraic) topology that at any moment, there is a point on the earth’s surface where no wind is blowing. -
Applications of Quantum Invariants in Low Dimensional Topology
View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by Elsevier - Publisher Connector Pergamon Topo/ogy Vol. 37, No. I, pp. 219-224, 1598 Q 1997 Elsevier Science Ltd Printed in Great Britain. All rights resewed 0040-9383197 $19.00 + 0.M) PII: soo4o-9383(97)00009-8 APPLICATIONS OF QUANTUM INVARIANTS IN LOW DIMENSIONAL TOPOLOGY STAVROSGAROUFALIDIS + (Received 12 November 1992; in revised form 1 November 1996) In this short note we give lower bounds for the Heegaard genus of 3-manifolds using various TQFT in 2+1 dimensions. We also study the large k limit and the large G limit of our lower bounds, using a conjecture relating the various combinatorial and physical TQFTs. We also prove, assuming this conjecture, that the set of colored SU(N) polynomials of a framed knot in S’ distinguishes the knot from the unknot. 0 1997 Elsevier Science Ltd 1. INTRODUCTION In recent years a remarkable relation between physics and low-dimensional topology has emerged, under the name of fopological quantum field theory (TQFT for short). An axiomatic definition of a TQFT in d + 1 dimensions has been provided by Atiyah- Segal in [l]. We briefly recall it: l To an oriented d dimensional manifold X, one associates a complex vector space Z(X). l To an oriented d + 1 dimensional manifold M with boundary 8M, one associates an element Z(M) E Z(&V). This (functor) Z usually satisfies extra compatibility conditions (depending on the di- mension d), some of which are: l For a disjoint union of d dimensional manifolds X, Y Z(X u Y) = Z(X) @ Z(Y). -
Recognizing Surfaces
RECOGNIZING SURFACES Ivo Nikolov and Alexandru I. Suciu Mathematics Department College of Arts and Sciences Northeastern University Abstract The subject of this poster is the interplay between the topology and the combinatorics of surfaces. The main problem of Topology is to classify spaces up to continuous deformations, known as homeomorphisms. Under certain conditions, topological invariants that capture qualitative and quantitative properties of spaces lead to the enumeration of homeomorphism types. Surfaces are some of the simplest, yet most interesting topological objects. The poster focuses on the main topological invariants of two-dimensional manifolds—orientability, number of boundary components, genus, and Euler characteristic—and how these invariants solve the classification problem for compact surfaces. The poster introduces a Java applet that was written in Fall, 1998 as a class project for a Topology I course. It implements an algorithm that determines the homeomorphism type of a closed surface from a combinatorial description as a polygon with edges identified in pairs. The input for the applet is a string of integers, encoding the edge identifications. The output of the applet consists of three topological invariants that completely classify the resulting surface. Topology of Surfaces Topology is the abstraction of certain geometrical ideas, such as continuity and closeness. Roughly speaking, topol- ogy is the exploration of manifolds, and of the properties that remain invariant under continuous, invertible transforma- tions, known as homeomorphisms. The basic problem is to classify manifolds according to homeomorphism type. In higher dimensions, this is an impossible task, but, in low di- mensions, it can be done. Surfaces are some of the simplest, yet most interesting topological objects. -
Floer Homology, Gauge Theory, and Low-Dimensional Topology
Floer Homology, Gauge Theory, and Low-Dimensional Topology Clay Mathematics Proceedings Volume 5 Floer Homology, Gauge Theory, and Low-Dimensional Topology Proceedings of the Clay Mathematics Institute 2004 Summer School Alfréd Rényi Institute of Mathematics Budapest, Hungary June 5–26, 2004 David A. Ellwood Peter S. Ozsváth András I. Stipsicz Zoltán Szabó Editors American Mathematical Society Clay Mathematics Institute 2000 Mathematics Subject Classification. Primary 57R17, 57R55, 57R57, 57R58, 53D05, 53D40, 57M27, 14J26. The cover illustrates a Kinoshita-Terasaka knot (a knot with trivial Alexander polyno- mial), and two Kauffman states. These states represent the two generators of the Heegaard Floer homology of the knot in its topmost filtration level. The fact that these elements are homologically non-trivial can be used to show that the Seifert genus of this knot is two, a result first proved by David Gabai. Library of Congress Cataloging-in-Publication Data Clay Mathematics Institute. Summer School (2004 : Budapest, Hungary) Floer homology, gauge theory, and low-dimensional topology : proceedings of the Clay Mathe- matics Institute 2004 Summer School, Alfr´ed R´enyi Institute of Mathematics, Budapest, Hungary, June 5–26, 2004 / David A. Ellwood ...[et al.], editors. p. cm. — (Clay mathematics proceedings, ISSN 1534-6455 ; v. 5) ISBN 0-8218-3845-8 (alk. paper) 1. Low-dimensional topology—Congresses. 2. Symplectic geometry—Congresses. 3. Homol- ogy theory—Congresses. 4. Gauge fields (Physics)—Congresses. I. Ellwood, D. (David), 1966– II. Title. III. Series. QA612.14.C55 2004 514.22—dc22 2006042815 Copying and reprinting. Material in this book may be reproduced by any means for educa- tional and scientific purposes without fee or permission with the exception of reproduction by ser- vices that collect fees for delivery of documents and provided that the customary acknowledgment of the source is given.