Algebraic Topology

Constructions, Retractions, and Fixed Point Theory

Smail Djebali

• Publisher: De Gruyter
• Year: 2024
• eBook ISBN: 9783111517780
• Edition: 0
• Topic: Mathematics
• Subtopic: Computer Science General
• Index: Mathematics

The aim of the textbook is two-fold: first to serve as an introductory graduate course in Algebraic Topology and then to provide an application-oriented presentation of some fundamental concepts in Algebraic Topology to the fixed point theory.

A simple approach based on point-set Topology is used throughout to introduce many standard constructions of fundamental and homological groups of surfaces and topological spaces. The approach does not rely on Homological Algebra. The constructions of some spaces using the quotient spaces such as the join, the suspension, and the adjunction spaces are developed in the setting of Topology only.

The computations of the fundamental and homological groups of many surfaces and topological spaces occupy large parts of the book (sphere, torus, projective space, Mobius band, Klein bottle, manifolds, adjunctions spaces). Borsuk's theory of retracts which is intimately related to the problem of the extendability of continuous functions is developed in details. This theory together with the homotopy theory, the lifting and covering maps may serve as additional course material for students involved in General Topology.

The book comprises 280 detailed worked examples, 320 exercises (with hints or references), 80 illustrative figures, and more than 80 commutative diagrams to make it more oriented towards applications (maps between spheres, Borsuk-Ulam Theory, Fixed Point Theorems, …) As applications, the book offers some existence results on the solvability of some nonlinear differential equations subject to initial or boundary conditions.

The book is suitable for students primarily enrolled in Algebraic Topology, General Topology, Homological Algebra, Differential Topology, Differential Geometry, and Topological Geometry. It is also useful for advanced undergraduate students who aspire to grasp easily some new concepts in Algebraic Topology and Applications. The textbook is practical both as a teaching and research document for Bachelor, Master students, and first-year PhD students since it is accessible to any reader with a modest understanding of topological spaces.

The book aspires to fill a gap in the existing literature by providing a research and teaching document which investigates both the theory and the applications of Algebraic Topology in an accessible way without missing the main results of the topics covered.

Table of contents

• Title Page
• Copyright
• Contents
• Introduction
• 1 Background in topology
• 2 Quotient topology
• 3 Topological constructions
• 4 The fundamental group
• 5 Covering maps and lifting maps
• 6 Fundamental groups of the circle and the sphere
• 7 Borsuk’s theory of retracts
• 8 Fundamental groups of some surfaces
• 9 Higher homotopy groups
• 10 Elements of homology theory
• 11 Fixed-point theorems
• 12 Applications
• Person Index
• Subject Index