What is...cellular approximation for spaces?

Goal.
Explaining basic concepts of algebraic topology in an intuitive way.

This time.
What is...cellular approximation for spaces? Or: My polynomials have cells.

Disclaimer.
Nobody is perfect, and I might have said something silly. If there is any doubt, then please check the references.

Disclaimer.
These videos are concerned with algebraic topology, and not general topology. (These two are not to be confused.) I assume that you know bits and pieces about general topology, but not too much, I hope.

Slides.

Website with exercises.

Cellular approximation.

Stone-Weierstrass approximation.

Hawaiian earrings and friends.

Whitehead’s theorem.

Homotopy groups of the Hawaiian earrings.

Pictures used.

Hatcher’s book (I sometimes steal some pictures from there).

Always useful.

Mathematica.

#algebraictopology
#topology
#mathematics