English

So, what is a derived functor?

Category Theory 2020-03-25 v4 Quantum Algebra

Abstract

In the context of infinity categories, we rethink the notion of derived functor in terms of correspondences. This is especially convenient for the description of a passage from an adjoint pair (F,G) of functors to a derived adjoint pair (LF,RG). In particular, canonicity of this passage becomes obvious. 2nd version: added comparison to Deligne's definition (SGA4) and a discussion of diagrams of derived functors. Introduction rewritten and references added. 3rd version: description of Kan extensions in terms of correspondences more detailed. 4th version: the final version accepted to HHA.

Keywords

Cite

@article{arxiv.1811.12255,
  title  = {So, what is a derived functor?},
  author = {V. Hinich},
  journal= {arXiv preprint arXiv:1811.12255},
  year   = {2020}
}

Comments

12 pages, Version 3: 16 pages

R2 v1 2026-06-23T06:25:25.856Z