New posts in homological-algebra

Getting the most general form of Mayer-Vietoris from the axioms of homology

Isomorphic cokernels giving isomorphic kernels

Ext and Tor duality

Being direct summand of free module implies having dual basis.

An example of computing Ext

Hochschild homology - motivation and examples

On equivalent definitions of Ext

Signs in the tensor product and internal hom of chain complexes

Why is the definition of $\lim^1$ via a cokernel the first derived functor of $\lim$?

Motivation for the mapping cone complexes

A direct product of projective modules which is not projective

$B$ a chain complex of free abelian groups and $C$ a chain complex such that $H_n(C)=0$. Then any chain map from $B$ to $C$ homotopic to the zero map

Is homology an adjoint functor?

Additive functors preserve split exact sequences

Alternative construction of Direct Limit

Why are we interested in cohomology?

showing exact functors preserve exact sequences (abelian categories, additive functors, and kernels)

Motivation for Koszul complex

History behind Exact Sequences.

Ext between two coherent sheaves