New posts in Homological Algebra

Exactness and obstruction in sheaf cohomology

Ext and Tor duality

Why does a filtration of a group consist of normal subgroups, and not any subgroups?

Derived proofs of elementary homological algebra theorems?

Does the Grothendieck group of finitely generated modules form a commutative ring where the multiplication structure is induced from tensor product?

How do you explain why the arguments of $\operatorname{Ext}^1(A,B)$ aren't "backwards"?

Induced map on cohomology being zero impies null-homotopic?

Cap product Hochschild (co)homology

Can we use the internal logic of a category to do diagram chases "as in $\mathbf{Ab}$" ?

Retraction and direct limit