New posts in Homology Cohomology

Exactness and obstruction in sheaf cohomology

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

Does an analogue of the sphere theorem hold in higher dimensions?

What is the "natural homomorphism" in the definition of an *essential manifold*?

Example of cw complexes quasi isomorphic but not homotopic.

Hatcher's Algebraic Topology. Exercise 2.2.42

Group cohomology of $PSU(n)$

$S^2$ is not a countable union of embedded circles $S^1$

Hatcher Exercise 2.1.26.

De Rham cohomology of compact manifold minus one point