Hochschild cohomology and group actions
Abstract
Given a finite group action on a (suitably enhanced) triangulated category linear over a field, we establish a formula for the Hochschild cohomology of the category of invariants, assuming the order of the group is coprime to the characteristic of the base field. The formula shows that the cohomology splits canonically with one summand given by the invariant subspace of the Hochschild cohomology of the original category. We also prove that Serre functors act trivially on Hochschild cohomology, and combine this with our formula to give a useful mechanism for computing the Hochschild cohomology of fractional Calabi-Yau categories.
Keywords
Cite
@article{arxiv.1807.09268,
title = {Hochschild cohomology and group actions},
author = {Alexander Perry},
journal= {arXiv preprint arXiv:1807.09268},
year = {2018}
}
Comments
21 pages, minor updates. This is a revised and expanded version of what was originally an appendix to arXiv:1605.06568v1