Topology Lecture 17: Adjunction Spaces

We discuss adjunction spaces which combine disjoint union spaces and quotient spaces.

00:00 Introduction
00:28 Def: Adjunction Space
04:37 Properties of Adjunction Spaces
21:35 Example: Wedge Sum
23:45 Example: Sphere from closed disks
26:32 Example: Glueing manifolds along their boundaries

This lecture follows Lee's "Introduction to topological manifolds", chapter 3.

A playlist with all the videos in this series can be found here:

[ChrisRossaroGG]

28:48 here one starts from two manifolds with boundaries (which are not manifolds) and eventually ends up with a manifold; impressive.

[ChrisRossaroGG]

22:30 this is the "Vel" symbol, the "Wedge" symbol is the Vel turned upside down.

[braindead]

I don’t think the wedge sum example quite works because we don’t know if the singleton {y0} is closed in Y. If it is closed, we can make the wedge sum, but I don’t think this works for a general topology Y.

[ChrisRossaroGG]

4:08 here is said that a point in A can have multiple values in f(A), how is that possible if f is a function?

[leodu]

I’m working through Jack Lee’s Introduction to Topological Manifolds and this series of videos the second best thing short of attending an actual manifold lecture!! (Actually in some ways it’s better because one can adjust watching speed to one’s own learning curve.)