New posts in Homology Cohomology

Cup and wedge product in singular and de Rham cohomology

Construction of connected closed oriented $4d-$dimensional manifold whose has only middle homology group is nontrivial.

Proof that degree of map is sum of its local degrees (prop 2.30 Hatcher)

Intuition behind cohomology operations

Calculating Ext and Tor for Z/mZ and Z/nZ

Cover for Cech cohomology of the constant sheaf $\mathbb{Z}$ over $\mathbb{P}^n$

Why group cohomology and not group homology?

The First Homology Group is the Abelianization of the Fundamental Group.

Intuition behind the Thom Isomorphism.

What's a cohomology that's not defined from a cochain complex?