1.1. Background. This paper deals with the landmark results of Benson and Carlson's Projective resolutions and Poincar e duality complexes [6]. Our goal is to provide some necessary background for that work, and to prove some of the results of [6] in a more general setting. In particular, we analyze what happens when we replace Benson and Carlson's complex C (in the notation of [6]) with an arb...

Let G be a finite group and k be a field of characteristic p. The connection between the modular representations and the cohomology of G has been a subject of major interest over the last several years. For example, recent study of the stable category of kG-modules StMod(kG) led Rickard [27] to introduce certain idempotent modules and functors. This has led to a theory of varieties for infinite...

A free bimodule resolution is constructed for the integral group ring of the dihedral group of order 4m. This resolution is applied for a description, in terms of generators and defining relations, of the Hochschild cohomology algebra of this group ring. Introduction Let K be a commutative ring with unity, let R be an associative K-algebra that is a finitely generated projective K-module, let Λ...

For every prime integer p, M. Hochster conjectured the existence of certain p-torsion elements in a local cohomology module over a regular ring of mixed characteristic. We show that Hochster’s conjecture is false. We next construct an example where a local cohomology module over a hypersurface has p-torsion elements for every prime integer p, and consequently has infinitely many associated prim...

Abstract We construct a $(\mathfrak {gl}_2, B(\mathbb {Q}_p))$ and Hecke-equivariant cup product pairing between overconvergent modular forms the local cohomology at $0$ of sheaf on $\mathbb {P}^1$ , landing in compactly supported completed {C}_p$ -cohomology curve. The group is highest-weight Verma module, non-trivial vector for any form infinitesimal weight not equal to $1$ . For classical $k...

Quasiperiodic patterns described by polyhedral “atomic surfaces” and admitting matching rules are considered. It is shown that the cohomology ring of the continuous hull of such patterns is isomorphic to that of the complement of a torus T to an arrangement A of thickened affine tori of codimension two. Explicit computation of Betti numbers for several two-dimensional tilings and for the icosah...

We study the vanishing of homology and cohomology of a module of finite complete intersection dimension over a local ring. Given such a module of complexity c, we show that if c (co)homology groups with a module of finite length vanish, then all higher (co)homology groups vanish.

We classify various types of graded extensions a finite braided tensor category $$\mathcal {B}$$ in terms its 2-categorical Picard groups. In particular, we prove that by group A correspond to monoidal 2-functors from the (consisting invertible central -module categories). Such functors can be expressed Eilnberg-Mac Lane cohomology. describe detail groups symmetric fusion categories and pointed...

There is much we still do not know about projective spaces. We describe here how the mod two cohomology of each real projective space is built as an unstable module over the Steenrod algebra A, or equivalently, over K, the algebra of inherently unstable mod two “lower operations” originally introduced by Steenrod. In particular, to produce the cohomology of projective space of each dimension we...