0
votes
2answers
58 views

About the definition of homology

can someone explaine me this definition of Homology: "The homology groups of $X$ measure "how-far" the chain complex associated to $X$ is from being exact." I know that homology measure the number ...
4
votes
1answer
300 views

Definition of simplicial approximation

I have been given the following definition of simplicial approximation in lectures: Let $K, L$ be simplicial complexes and $f : |K| \to |L|$ be a continuous map of their polyhedra. A simplicial ...