Deligne asked in 1993 whether the Hochschild cochain complex of an associative ring has a natural action by the singular chains of the little 2-cubes operad. In this paper we give an affirmative answer to this question. We also show that the topological Hochschild cohomology spectrum of an associative ring spectrum has an action by an operad that is equivalent to the little 2-cubes operad.

We show that the deformations of the de Rham cohomology of a closed simply connected KK ahler manifold are governed by the dual of real-valued cohomology of its free loop space. A currently very active eld in Mathematics is the theory of quantum cohomol-ogy, which provides a special kind of deformations of the multiplication structure on the de Rham cohomology of symplectic manifolds. The mathe...

The main result of this paper is to calculate the Batalin-Vilkovisky structure of HH∗(C∗(KPn;R);C∗(KPn;R)) for K = C andH, and R = Z and any field; and shows that in the special case when M = CP 1 = S2, and R = Z, this structure can not be identified with the BV-structure of H∗(LS 2;Z) computed by Luc Memichi in [16]. However, the induced Gerstenhaber structures are still identified in this cas...

In this paper we show that Gorensteinness, singularity categories and the finite generation condition Fg for Hochschild cohomology are invariants under arrow removal operation a dimensional algebra.

We give some general results on the ring structure of Hochschild cohomology of smash products of algebras with Hopf algebras. We compute this ring structure explicitly for a large class of finite dimensional Hopf algebras of rank one.

We prove that certain classes of von Neumann algebras with regular, injective subalgebras are thin. As a consequence, all Hochschild cohomology groups of these algebras are zero. Mathematics subject classification (2010): 46L10, 47A16.

We calculate the Gerstenhaber bracket on Hopf algebra and Hochschild cohomologies of Taft Tp for any integer p>2 which is a nonquasi-triangular algebra. show that indeed zero cohomology Tp, as in all known quasi-triangular algebras. This example first computation Also, we find general formula with bijective antipode bar resolution reminiscent Gerstenhaber's original cohomology.