New posts in Algebraic Topology

Simple explanation for what a torsor is

Why is it important to have a classifying space for principal $G$-bundles over a based space $X$?

Does every finite $CW$ complex have the homotopy type of a smooth manifold? How about infinite $CW$ complexes?

Exactness and obstruction in sheaf cohomology

Example of a space whose complex K-theory is not easily computable from singular cohomology

Every continuous map $f:\mathbb{C}P(2) \to \mathbb{C}P(2)$ has a fixed point, without Lefschetz theorem.

Degree of a map $T^2\to T^2$ induced by an $2\times 2$ integer matrix

Sheafification of a subpresheaf

What is the purpose of the category of topological pairs?

$4$-manifold with fundamental group $\Bbb Z/4\Bbb Z$