New posts in Homological Algebra

$f_*$ induces an isomorphism in homology iff the mapping cone of $f_*$ is contractible.

counterexample for $f_*:C_*\to D_*$ be a chain map such that $f_*$ induces an isomorphism in homology. Then $f_*$ is a chain homotopy equivalence

Positivity of the alternating sum associated to at most five subspaces

A categorical perspective on the equivalence of sheaf cohomology and Cech cohomology?

When does tensor product have a (exact) left adjoint?

Injective resolutions of a complex

How to show fraction field is flat (without localization)

Homology and (co)Limits

Exact sequence with flat module tensored by module stays exact

Contents of Tor modules