(There will also be a web page on Courseworks.)

Time: TTh 4:10-5:25 p.m.
Place: Math 417
Textbook: Topology (second edition) by James Munkres.
Office hours: TTh 5:30-6:30 p.m. in Math 424.
Office Hours: M 2:00-3:00; Th 3:00-4:00. In Math 408.
Help room hours: M 2:00-4:00 p.m.
Final exam date: December 22, 4:10 p.m.-7:00 p.m.
Announcements:

## Prerequisites.

One semester of "Introduction to Modern Algebra" (Math W4041) or equivalent is required: the second half of "Topology" will use some group theory, and we will assume some familiarity with writing proofs. A course in analysis (Math V1208 or W4061) is recommended, as well: many of the ideas of the first half of the semester are generalizations of ideas from analysis, and it is easier to develop an intuition in the more restricted setting.

## Description and goals.

Topology is, somewhat tautologically, the study of topological spaces and continuous maps. Roughly, it focuses on qualitative, as opposed to quantitative, properties of spaces and functions.

The first half of the semester will be devoted to point-set topology -- the axioms of topological spaces and what they imply. These notions are central to modern mathematics, and are core tools in almost all parts of the field. The second half of the semester will be an introduction to algebraic topology, via the fundamental group and a little covering space theory. This is the starting point for most of modern topology, and one of the first places one encounters the viewpoint of modern mathematics.

## Policies.

 Homework 40% Midterm exam 25% Final exam 35%

The lowest homework score will be dropped.

### Homework

Problem sets are due on Tuesdays at the beginning of class, except as noted below. If you can't make it to class, put it in my mailbox before class.

You're welcome to work on the homework together. However, you must write up your final answers by yourself. I consider writing them up together cheating.

You are also generally welcome to use any resources you like to solve the problems. However, any resource you use other than the textbook (Munkres) must be cited in your homework. This includes electronic resources (including Wikipedia and Google) and human resources (including the help room and your classmates). Failure to cite sources constitutes academic misconduct.

### Students with disabilities

Students with disabilities requiring special accommodation should contact Office of Disability Services (ODS) promptly to discuss appropriate arrangements.

### Missed exams

If you have a conflict with any of the exam dates, you must contact me ahead of time so we can make arrangements. (At least a week ahead is preferable.) If you are unable to take the exam because of a medical problem, you must go to the health center and get a note from them -- and contact me as soon as you can.

## Syllabus and schedule.

Note: "+" indicates material not discussed in the textbook. Material in parentheses will probably be omitted from class (but discussed in problem sets).

Date Material Textbook Announcements
09/08 Metric spaces and continuous maps. + (Recommend: Rudin, Principles of Mathematical Analysis, §2.2) Welcome to W4051.
09/10 Topological spaces and continuous maps. §12, 13, most of 18, 20
09/15 Examples of topologies. §13, 14, 15, 16 Problem set 1 due.
09/17 Closures, interiors, the Hausdorff axiom. Infinite products of spaces. §17, 19, (rest of 18, 20, 21)
09/22 The quotient topology. Surfaces. §22, + Problem set 2 due.
09/24 Connectedness and path connectedness. §23, 24, 25, +
09/29 Compactness. §26, 27 Problem set 3 due.
10/01 Interlude: knots, surfaces and all that. +
10/06 More on compactness. §28, 29 Problem set 4 due.
10/08 Countability and separation axioms. §30, 31
10/13 Normal spaces and the Urysohn lemma. §32, 33 Problem set 5 due.
10/15 The Urysohn Metrization Theorem and the Tietze Extension Theorem. §34, 35
10/20 Midterm
10/22 Review of groups. Homotopies. §51, +

10/27

The fundamental group. The fundamental group of the circle (announcement). The Brouwer fixed point theorem. §52, 55 Problem set 6 (short) due.
10/29 More applications of the fundamental group. §56, 57
11/03

Election day: go vote!

11/05

Deformation retracts and homotopy equivalence.

§58

Problem set 7 due.
11/10

More homotopy equivalence. Towards the van Kampen theorem.

§58, 67-68

11/12

Free groups, amalgamated products, generators and relations.

§67-69
11/17 Statement of the van Kampen theorem. Examples. §70, 71, + Problem set 8 due.
11/19 More examples with the van Kampen theorem. (Maybe some knot theory.) +
11/24

Covering spaces and the fundamental group of the circle.

§53, 54 Problem set 9 due.
11/26

No class: be thankful.

12/1 Proof of the van Kampen theorem. §70
12/3 Classification of surfaces I: seeing when they're different. §74, 75
12/8 Classification of surfaces II: seeing when they're the same. §76-78, + Problem set 10 due.
12/10 Introduction to knot theory. Or something else. +

## Problem sets.

• Problem set 1 (PDF). Due September 15.
• Very slighty updated on 09/08.
• (One problem refers to the ordinals handout, the first few sections of which are on Courseworks in the "Class Files" section.)
• Solutions now posted on Courseworks, in class files section. (Tell me if you find errors.)
• Problem set 2 (PDF). Due September 22.
• Solutions posted on Courseworks.
• Problem set 3 (PDF). Due September 29.
• Solutions posted on Courseworks.
• Problem set 4 (PDF). Due October 6.
• Solutions posted on Courseworks.
• Problem set 5 (PDF). Due October 13.
• Solutions posted on Courseworks.
• Problem set 6 (PDF). Due October 27.
• Solutions posted on Courseworks.
• Problem set 7 (PDF). Due November 5.
• Solutions posted on Courseworks.
• Problem set 8 part 1 and part 2 (PDF). Due November 17.
• Solutions posted on Courseworks.
• Problem set 9 (PDF). Due November 24.
• Solutions posted on Courseworks.
• Problem set 10 (PDF). Due December 8.
• Problem set 11 (PDF). Due December 15.