New posts in homology-cohomology

The simplest nontrivial (unstable) integral cohomology operation

algebraic-topology homology-cohomology cohomology-operations

Why are period integrals naïve periods?

algebraic-geometry definite-integrals homology-cohomology arithmetic-geometry

Torsion-free virtually-Z is Z

group-theory homology-cohomology group-cohomology

Calculating the cohomology with compact support of the open Möbius strip

algebraic-topology homology-cohomology

Is homology with coefficients in a field isomorphic to cohomology?

algebraic-topology homology-cohomology

Meaning of "efface" in "effaceable functor" and "injective effacement"

terminology homology-cohomology abelian-categories derived-functors

Vanishing differential forms in cohomology

differential-geometry homology-cohomology de-rham-cohomology

Conditions for null-homotopic chain map in a specific example

abstract-algebra homology-cohomology homological-algebra

Poincare Duality Reference

reference-request algebraic-topology homology-cohomology

Finding $\text{Ext}_R^n(M,R)$ and $\text{Ext}_R^n(M,N)$ for a particular case

commutative-algebra homology-cohomology homological-algebra

Motivating Cohomology

general-topology algebraic-topology homology-cohomology

Cohomology of projective plane

algebraic-topology differential-topology homology-cohomology

Why homology with coefficients?

algebraic-topology homology-cohomology

Surprising applications of cohomology

soft-question homological-algebra big-list homology-cohomology applications

Do open embeddings preserve the intersection pairing?

algebraic-topology differential-topology smooth-manifolds homology-cohomology

Two fold map while calculating Mayer–Vietoris sequence of $\mathbb RP^2$.

algebraic-topology homology-cohomology mayer-vietoris-sequence

Natural isomorphism for a reduced cohomology theory on CW complexes.

algebraic-topology homology-cohomology

how to compute the de Rham cohomology of the punctured plane just by Calculus?

calculus differential-geometry algebraic-topology homology-cohomology smooth-manifolds

Proof of $\tilde{H}_*(X) \cong H_*(X, x_0) $.

algebraic-topology homology-cohomology exact-sequence

Calculating Ext and Tor for $\mathbb Z/m\mathbb Z$ and $\mathbb Z/n\mathbb Z$

homology-cohomology projective-module