Tate resolutions for commutative graded algebras over a local ring
The almost isomorphism relation for simple regular rings.
A longstanding open problem in the theory of von Neumann regular rings is the question of whether every directly finite simple regular ring must be unit-regular. Recent work on this problem has been done by P. Menal, K. C. O'Meara, and the authors. To clarify some aspects of these new developments, we introduce and study the notion of almost isomorphism between finitely generated projective modules over a simple regular ring.
The Auslander generators of the exterior algebra in two variables
We compute a complete set of nonisomorphic minimal Auslander generators for the exterior algebra in two variables.
The Batalin-Vilkovisky Algebra on Hochschild Cohomology Induced by Infinity Inner Products
We define a BV-structure on the Hochschild cohomology of a unital, associative algebra with a symmetric, invariant and non-degenerate inner product. The induced Gerstenhaber algebra is the one described in Gerstenhaber’s original paper on Hochschild-cohomology. We also prove the corresponding theorem in the homotopy case, namely we define the BV-structure on the Hochschild-cohomology of a unital -algebra with a symmetric and non-degenerate -inner product.
The category of abelian Hopf algebras
The Cohomology Ring of a Monomial Algebra.
The cohomology ring of free loop spaces.
The composite of irreducible morphisms in regular components
We study when the composite of n irreducible morphisms between modules in a regular component of the Auslander-Reiten quiver is non-zero and lies in the n+1-th power of the radical ℜ of the module category. We prove that in this case such a composite belongs to . We apply these results to characterize those string algebras having n irreducible morphisms between band modules such that their composite is a non-zero morphism in .
The Construction of Almost Split Sequences, III: Modules Over Two Classes of Tame Local Algebras.
The cyclic homology of the group rings.
The dimension of the derived category of elliptic curves and tubular weighted projective lines
We show that the dimension of the derived category of an elliptic curve or a tubular weighted projective line is one. We give explicit generators realizing this number, and show that they are in a certain sense minimal.
The Dirac complex on abstract vector variables: megaforms.
The duality theorem for twisted smash products of Hopf algebras and its applications
Let denote the twisted smash product of an arbitrary algebra A and a Hopf algebra H over a field. We present an analogue of the celebrated Blattner-Montgomery duality theorem for , and as an application we establish the relationship between the homological dimensions of and A if H and its dual H* are both semisimple.
The existence of Galois sets
The existence of relative pure injective envelopes
Let 𝓢 be a class of finitely presented R-modules such that R∈ 𝓢 and 𝓢 has a subset 𝓢* with the property that for any U∈ 𝓢 there is a U*∈ 𝓢* with U* ≅ U. We show that the class of 𝓢-pure injective R-modules is preenveloping. As an application, we deduce that the left global 𝓢-pure projective dimension of R is equal to its left global 𝓢-pure injective dimension. As our main result, we prove that, in fact, the class of 𝓢-pure injective R-modules is enveloping.
The Extraordinary Derived Category.
The flat dimensions of injective modules.
The Gelfand-Kirillov Dimension of a Tensor Product.
The general structure of inverse polynomial modules
In this paper we compute injective, projective and flat dimensions of inverse polynomial modules as -modules. We also generalize Hom and Ext functors of inverse polynomial modules to any submonoid but we show Tor functor of inverse polynomial modules can be generalized only for a symmetric submonoid.
The global homological dimension of semi-trival extensions of rings.