Realizability of cohomology algebras: a survey

A Survey of Hochschild Cohomology for von Neumann Algebras

In this paper we survey the field of Hochschild cohomology for von Neumann algebras. We describe the basic definitions and results without assuming background knowledge beyond some familiarity with von Neumann algebra theory. We offer no formal proofs of results, although we give detailed references to the literature. Instead, we concentrate on explaining the main techniques and how they are ap...

Module cohomology group of inverse semigroup algebras

Let $S$ be an inverse semigroup and let $E$ be its subsemigroup of idempotents. In this paper we define the $n$-th module cohomology group of Banach algebras and show that the first module cohomology group $HH^1_{ell^1(E)}(ell^1(S),ell^1(S)^{(n)})$ is zero, for every odd $ninmathbb{N}$. Next, for a Clifford semigroup $S$ we show that $HH^2_{ell^1(E)}(ell^1(S),ell^1(S)^{(n)})$ is a Banach sp...

a structural survey of the polish posters

تصویرسازی قابلیتهای فراوانی را دارا است

Second Hochschild Cohomology of Convolution Algebras

Realizability of Modules over Tate Cohomology

Let k be a field and let G be a finite group. There is a canonical element in the Hochschild cohomology of the Tate cohomology γG ∈ HH3,−1Ĥ∗(G, k) with the following property. Given a graded Ĥ∗(G, k)-module X, the image of γG in Ext 3,−1 Ĥ∗(G,k) (X,X) vanishes if and only if X is isomorphic to a direct summand of Ĥ∗(G,M) for some kG-module M . The description of the realizability obstruction wo...