Hochschild and Ordinary Cohomology Rings of Small Categories

Second Hochschild Cohomology of Convolution Algebras

Hochschild Homology and Semiorthogonal Decompositions

We investigate Hochschild cohomology and homology of admissible subcategories of derived categories of coherent sheaves on smooth projective varieties. We show that the Hochschild cohomology of an admissible subcategory is isomorphic to the derived endomorphisms of the kernel giving the corresponding projection functor, and the Hochschild homology is isomorphic to derived morphisms from this ke...

Gerstenhaber Brackets on Hochschild Cohomology of Twisted Tensor Products

We construct the Gerstenhaber bracket on Hochschild cohomology of a twisted tensor product of algebras, and, as examples, compute Gerstenhaber brackets for some quantum complete intersections arising in work of Buchweitz, Green, Madsen, and Solberg. We prove that a subalgebra of the Hochschild cohomology ring of a twisted tensor product, on which the twisting is trivial, is isomorphic, as a Ger...

Computing group cohomology rings from the Lyndon-Hochschild-Serre spectral sequence

We describe a method for computing presentations of cohomology rings of small finite p-groups. The description differs from other accounts in the literature in two main respects. First, we suggest some techniques for improving the efficiency of the obvious linear algebra approach to computing projective resolutions over a group algebra. Second, we use an implementation of the multiplicative str...

Green functors, crossed G-monoids, and Hochschild constructions

Let G be a finite group, and R be a commutative ring. This note proposes a generalization to any Green functor for G over R of the construction of the Hochschild cohomology ring HH∗(G,R) from the ordinary cohomology functor H∗(−, R). Another special case is the construction of the crossed Burnside ring of G from the ordinary Burnside functor. The general abstract setting is the following : let ...