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(Co)chain complexes, abelian Categories, (pre)sheaves, (co)homology in various (possibly highly generalized) settings, spectra, derived functors, resolutions, spectral sequences, homotopy categories. Chain complexes in an abelian category form the heart of homological algebra.

3 votes
1 answer
176 views

Coinciding induced maps

Of course if two morphisms of complexes are homotopic their induced maps coincide, but I'm wondering about the converse: if the induced maps on the cohomologies coincide, when does that imply that the …
AAK's user avatar
  • 5,901
10 votes
1 answer
9k views

Examples of computing Ext and Tor functors?

So I understand in theory the definition of Ext and Tor, but when it comes to actually computing them, I'm stuck. For example, could someone show me how to compute $\text{Ext}(\mathbb{Z}/m\mathbb{Z}, …
AAK's user avatar
  • 5,901
6 votes
Accepted

Do $RHom(C,D)$ and $DG(C,D)$ have equivalent homotopy categories?

Toen proved that $RHom$ provides the internal hom in the homotopy category of dg-categories. For what you want to be true, you need something more than this: you need to know that $RHom$ is actually …
AAK's user avatar
  • 5,901