The global homological dimension of semi-trival extensions of rings.
Let M be a closed orientable manifold of dimension dand be the usual cochain algebra on M with coefficients in a fieldk. The Hochschild cohomology of M, is a graded commutative and associative algebra. The augmentation map induces a morphism of algebras . In this paper we produce a chain model for the morphism I. We show that the kernel of I is a nilpotent ideal and that the image of I is contained in the center of , which is in general quite small. The algebra is expected to be isomorphic...
This paper studies the Hochschild cohomology of finite-dimensional monomial algebras. If Λ = K/I with I an admissible monomial ideal, then we give sufficient conditions for the existence of an embedding of into the Hochschild cohomology ring HH*(Λ). We also introduce stacked algebras, a new class of monomial algebras which includes Koszul and D-Koszul monomial algebras. If Λ is a stacked algebra, we prove that , where is the ideal in HH*(Λ) generated by the homogeneous nilpotent elements. In...
We determine the algebra structure of the Hochschild cohomology of the singular cochain algebra with coefficients in a field on a space whose cohomology is a polynomial algebra. A spectral sequence calculation of the Hochschild cohomology is also described. In particular, when the underlying field is of characteristic two, we determine the associated bigraded Batalin-Vilkovisky algebra structure on the Hochschild cohomology of the singular cochain on a space whose cohomology is an exterior algebra....
We describe the images of multilinear polynomials of arbitrary degree evaluated on the upper triangular matrix algebra over an infinite field.
The rational completion of an -module can be characterized as a -injective hull of with respect to a (hereditary) torsion functor depending on . Properties of a torsion functor depending on an -module are studied.