Computing homology groups | Algebraic Topology | NJ Wildberger

Resource | v1 | created by jjones |
Type Video
Created 2012-10-12
Identifier unavailable


The definition of the homology groups H_n(X) of a space X, say a simplicial complex, is quite abstract: we consider the complex of abelian groups generated by vertices, edges, 2-dim faces etc, then define boundary maps between them, then take the quotient of kernels mod boundaries at each stage, or dimension. To make this more understandable, we give in this lecture an in-depth look at some examples. Here we start with the simplest ones: the circle and the disk. For each space it is necessary to look at each dimension separately. The 0-th homology group H_0(X) measures the connectivity of the space X, for a connected space it is the infinite cyclic group Z of the integers. The first homology group H_1 measures the number of independent non-trivial loops in the space (roughly). The second homology group H_2 measures the number of independent non-trivial 2-dim holes in the space, and so on.


about Homology

In mathematics, homology is a general way of associating a sequence of algebraic objects, such as abe...

Edit details Edit relations Attach new author Attach new topic Attach new resource
9.0 /10
useless alright awesome
from 1 review
Write comment Rate resource Tip: Rating is anonymous unless you also write a comment.
Resource level 3.0 /10
beginner intermediate advanced
Resource clarity 9.0 /10
hardly clear sometimes unclear perfectly clear
Reviewer's background 3.0 /10
none basics intermediate advanced expert
Comments 1
0 0

9 rating 3 level 9 clarity 3 user's background

Great intro to homology groups, has follow-up videos with more details