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Point Set Topology

Prof. Ronnie Sebastian · IIT Bombay

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About

Point set topology is one of the most important and basic courses that one encounters during a masters program in mathematics. This course introduces students to the most important concepts in point set topology. We begin the course by defining topological spaces and introducing various ways to put topologies on sets. Then we introduce the notion of continuous maps which enables us to see how different topological spaces interact with each other. A very special class of topological spaces is metric spaces. Most of our intuition for topology comes from metric spaces. We introduce metric spaces and try to understand the concepts we have learnt so far in this special case. After this we study the topological properties of connectedness, compactness and local compactness. We then introduce another method to put a topology on a set, namely the quotient topology. Finally we end the course with a discussion on when a topology arises from a metric. The main result in this part is Urysohn's Metrization Theorem.

Throughout this course, the emphasis will be on various examples which we encounter often in mathematics, like Euclidean spaces, spheres, subsets of Euclidean spaces, matrices, general linear group, special linear group, orthogonal group, unitary group, special orthogonal group, special unitary group, Grassmannians, projective spaces. Our aim will be to try and see if these spaces are connected, path connected, Hausdorff, compact, locally compact. The focus of this course is not going to be on constructing counterexamples. There are far too many useful things in topology to focus on, and so I feel it would be better to learn these, than spend time on counterexamples which serve little purpose later.

This course will be useful and accessible to students doing a masters in mathematics. The course can also be useful to students in a bachelors program in mathematics, physics or engineering streams, who need mathematics in their studies or have some interest in pure…

Lectures

Week 1

  1. Lecture 1.1: Definition and examples of topological spaces YouTube
  2. Lecture 1.2: Examples of topological spaces YouTube
  3. Lecture 1.3: Basis for topology YouTube
  4. Lecture 1.4: Subspace Topology YouTube
  5. Lecture 1.5: Product Topology YouTube

Week 2

  1. Lecture 2.1: Product Topology (continued) YouTube
  2. Lecture 2.2: Continuous maps YouTube
  3. Lecture 2.3: Continuity of addition and multiplication maps YouTube
  4. Lecture 2.4: Continuous maps to a product YouTube
  5. Lecture 2.5: Projection from a point YouTube

Week 3

  1. Lecture 3.1: Closed subsets YouTube
  2. Lecture 3.2: Closure YouTube
  3. Lecture 3.3: Joining continuous maps YouTube
  4. Lecture 3.4: Metric spaces YouTube
  5. Lecture 3.5: Connectedness YouTube

Week 4

  1. Lecture 4.1: Connectedness (continued) YouTube
  2. Lecture 4.2: Connectedness (continued) YouTube
  3. Lecture 4.3: Connected components YouTube
  4. Lecture 4.4: Path connectedness YouTube
  5. Lecture 4.5: Path connectedness (continued) YouTube

Week 5

  1. Lecture 5.1: Connectedness of GL(n,R)^+ (math symbol) YouTube
  2. Lecture 5.2: Connectedness of GL(n,C), SL(n,C), SL(n,R) YouTube
  3. Lecture 5.3: Compactness YouTube
  4. Lecture 5.4: Compactness (continued) YouTube
  5. Lecture 5.5: Compactness (continued) YouTube

Week 6

  1. Lecture 6.1: Compactness (continued) YouTube
  2. Lecture 6.2: SO(n) is connected YouTube
  3. Lecture 6.3: Compact metric spaces YouTube
  4. Lecture 6.4: Lebesgue Number Lemma YouTube
  5. Lecture 6.5: Locally compact spaces YouTube

Week 7

  1. Lecture 7.1: One point compactification YouTube
  2. Lecture 7.2: One point compactification (continued) YouTube
  3. Lecture 7.3: Uniqueness of one point compatification YouTube
  4. Lecture 7.4: Quotient topology YouTube
  5. Lecture 7.5: Quotient topology on G/H YouTube
  6. Lecture 7.6: Grassmannian YouTube

Week 8

  1. Lecture 8.1: Normal topological spaces YouTube
  2. Lecture 8.2: Urysohn’s Lemma YouTube
  3. Lecture 8.3: Tietze Extension Theorem YouTube
  4. Lecture 8.4: Regular and Second Countable spaces YouTube
  5. Lecture 8.5: Product Topology on \mathbb{R}^{\mathbb{N}} YouTube
  6. Lecture 8.6: Urysohn’s Metrization Theorem YouTube

Syllabus and materials

At NPTEL, as the course publishes them.

Credits and licence

Institution
IIT Bombay
Department
Mathematics
Teacher
Prof. Ronnie Sebastian
Level
Undergraduate
Language
English
Subjects
Mathematics
Source
NPTEL
Licence
CC BY-NC-SA, as NPTEL states it. Non-commercial use only. NPTEL's terms
Attribution
NPTEL states: "Distributed under Creative Commons Attribution-ShareAlike / CC BY - NC - SA", beside a BY-NC-SA badge.
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