Characteristic modules and tensor products over quasi-hereditary algebras

Let A be a monomial quasi-hereditary algebra with a pure strong exact Borel subalgebra B.It is proved that the category of induced good modules over B is contained in the category of good modules over A;that the characteristic module of A is an induced module of that of B via the exact functor-(?)_B A if and only if the induced A-module of an injective B-module remains injective as a B-module.Moreover,it is shown that an exact Borel subalgebra of a basic quasi-hereditary serial algebra is right serial and that the characteristic module of a basic quasi-hereditary serial algebra is exactly the induced module of that of its exact Borel subalgebra.     

Δ-tame quasi-hereditary algebras

Let (K, M, H) be an upper triangular biomodule problem. Brüstle and Hille showed that the opposite algebra A of the endomorphism algebra of a projective generator P of the matrices category of (K, M, H) is quasi-hereditary, and there is an equivalence between the category of Δ-good modules of A and Mat(K, M). In this note, based on the tame theorem for bimodule problems, we show that if the algebra A associated with an upper triangular bimodule problem is of Δ-tame representation type, then the category F(Δ) has the homogeneous property, i.e. almost all modules in F(Δ) are isomorphic to their Auslander-Reiten translations. Moreover, if (K, M, H) is an upper triangular bipartite bimodule problem, then A is of Δ-tame representation type if and only if F(Δ) is homogeneous.     

ON Δ-GOOD MODULE CATEGORIES ARISING FROM HEREDITARY ALGEBRAS

Let A be a hereditary artin algebra and M a complete exceptional sequence over A. Let F(M) be the subcategory of A-mod consisting of modules with an M-filtration. A quasi-hereditary algebra is called e-quasi-hereditary provided that its Δ-good module category is equivalent to the category F(M) under an exact functor. A characterization of e-quasi-hereditary algebras is given, and a connection between the representation type of F(Δ) and the Tits form associated to it for some e-quasi-hereditary algebras is obtained in this paper.     

双模问题rad~t(-,-)与拟遗传代数

设 Ｂ是 Ｋｒｕｌｌ－ｓｃｈｍｉｄｔ范畴 Ｋ上的一个上三角双模，Ｂｒｕｓｔｌｅ和 Ｈｉｌｌｅ证明了Ｂ的矩阵范畴ｍａｔＢ的投射生成子Ｐ的自同态代数的反代数Ａ是拟遗传代数，而且代数Ａ的△－好模范畴与ｍａｔＢ等价．本文把这些结果推广到由Ｃｒａｗｌｅｙ-Ｂｏｅｖｅｙ给出的具有非零导子的双模上，并在此基础上着重讨论了遗传代数 的投射模范畴Ｐｒｏｊ上的双模ｒａｄｔ（－，－），刻画了它所对应的拟遗传代数的Ｇａｂｒｉｅｌ箭图与关系，以及它们的特征模和Ｒｉｎｇｅｌ对偶．     

DG Poisson algebra and its universal enveloping algebra

We introduce the notions of differential graded (DG) Poisson algebra and DG Poisson module. Let A be any DG Poisson algebra. We construct the universal enveloping algebra of A explicitly, which is denoted by A^ue. We show that A^ue has a natural DG algebra structure and it satisfies certain universal property. As a consequence of the universal property, it is proved that the category of DG Poisson modules over A is isomorphic to the category of DG modules over A^ue. Furthermore, we prove that the notion of universal enveloping algebra A^ue is well-behaved under opposite algebra and tensor product of DG Poisson algebras. Practical examples of DG Poisson algebras are given throughout the paper including those arising from differential geometry and homological algebra.     

△-tame quasi-hereditary algebras

Let (K, M, H) be an upper triangular bimodule problem. Brüstle and Hille showed that the opposite algebra A of the endomorphism algebra of a projective generator P of the matrices category of (K, M, H) is quasi-hereditary, and there is an equivalence between the category of △-good modules of A and Mat(K, M). In this note, based on the tame theorem for bimodule problems, we show that if the algebra A associated with an upper triangular bimodule problem is of △-tame representation type, then the category F(△) has the homogeneous property, i.e. almost all modules in F(△) are isomorphic to their Auslander-Reiten translations. Moreover, if (K, M, H) is an upper triangular bipartite bimodule problem, then A is of △-tame representation type if and only if F(△) is homogeneous.     

DOI-KOPPINEN HOPF BIMODULES ARE MODULES

I construct a generalized twisted smash product A ^H B, which gives an abstract structure of Cibils-Rosso's algebra X associated to a finite-dimensional Hopf algebra H, for the H-bimodule algebra A and H-bicomodule algebra B. I show that the Doi-Koppinen Hopf (H, B, D)-bimodules are modules over a certain algebra which is of this type. Moreover, if D is finitely generated projective as a k-module, there exists a k-module-preserving equivalence of categories between the category of Doi-Koppinen (H, B, D)-Hopf bimodules and the category of left (D ^*op ? D ^*) ^{H?H op} (B ? B ^op )-modules.     

Hochschild Cohomology of an Algebra Associated with a Circular Quiver

In this article we show that an algebra A = K Γ/(f(X ^s )) has a periodic projective bimodule resolution of period 2, where KΓ is the path algebra of the circular quiver Γ with s vertices and s arrows over a commutative ring K, f(x) is a monic polynomial over K and X is the sum of all arrows in KΓ. Moreover, by means of this projective bimodule resolution, we compute the Hochschild cohomology group of A, and we give a presentation of the Hochschild cohomology ring HH?(A) by the generators and the relations in the case K is a field.     

Tilting modules over split-by-nilpotent extensions

Let a finite dimensional algebra R be a split extension of an algebra A by a nilpotent bimodule Q. We give necessary and sufficient conditions for a (partial) tilting module T_A to be such that T?_A R_R is a (partial) tilting module. If this is not the case, but Q_A is generated by the tilting module T_A , then there exists a quotient [Rbar] of R such that T?_A [Rbar]_[Rbar] is a tilting module.     

On the nuclearity of certain Cuntz‐Pimsner algebras

In the present paper, we give a short proof of the nuclearity property of a class of Cuntz‐Pimsner algebras associated with a Hilbert ??‐bimodule ??, where ?? is a separable and nuclear C *‐algebra. We assume that the left ??‐action on the bimodule ?? is given in terms of compact module operators and that ?? is direct summand of the standard Hilbert module over ?? (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

On twisted smash products for bimodule algebras and the drinfeld double 1

In this paper we construct a new algebra AHof an H- bimodule algebra Aby a Hopf algebra Hand study some of its properties. The smash product, the Drinfel'd double D(H) and the Doi-Takeuchi's algebra B?,H, are all special cases of AH. Moreover,we find a necessary and sufficient condition for A Hto be a Hopf algebra and also consider the dual situation     

On Quiver Grassmannians and Orbit Closures for Gen-Finite Modules

We show that endomorphism rings of cogenerators in the module category of a finite-dimensional algebra A admit a canonical tilting module, whose tilted algebra B is related to A by a recollement. Let M be a gen-finite A-module, meaning there are only finitely many indecomposable modules generated by M. Using the canonical tilts of endomorphism algebras of suitable cogenerators associated to M, and the resulting recollements, we construct desingularisations of the orbit closure and quiver Grassmannians of M, thus generalising all results from previous work of Crawley-Boevey and the second author in 2017. We provide dual versions of the key results, in order to also treat cogen-finite modules.

     

L'algebre de hopf bitensorielle

For any field k of zero characteristic we give a functor from the category of k-vector spaces into the category of k-Hopf algebras, attaching to any vector space V its bitensorial pointed Hopf algebra A^v. This Hopf algebra is graded, fulfills a universal property, and contains a remarkable subspace P of primitive elements, which as a conjecture may generate the Lie algebra Prim A^v. In case V is finite-dimensional we exhibit a Hopf pairing between A^vand A^v-whose kernel contains the (Hopf) ideal generated by the elements of P of degree ? 2.     

对应于根双模的拟遗传代数的Hochschild上同调群

设A是有限表示型遗传代数A=kQ的投射模范畴proj A上的根双模rad(-,-)所对应的拟遗传代数,基于Bardzell构造的极小投射双模分解,A的各阶Hochschild上同调群的维数被清晰地计算．     

Morita Duality for the Rings of Generalized Power Series

Let A, B be associative rings with identity, and (S, ≤) a strictly totally ordered monoid which is also artinian and finitely generated. For any bimodule _A M _B , we show that the bimodule _{[[ AS,≤ ]]}[M ^{S ,≤}]_{[[ BS, ≤ ]]} defines a Morita duality if and only if _A M _B defines a Morita duality and A is left noetherian, B is right noetherian. As a corollary, it is shown that the ring [[A ^{S ,≤}]] of generalized power series over A has a Morita duality if and only if A is a left noetherian ring with a Morita duality induced by a bimodule _A M _B such that B is right noetherian. Received April 13, 1999, Accepted December 12, 1999     

Stratified modules over an extension algebra

Let A be a standard Koszul standardly stratified algebra and X an A-module. The paper investigates conditions which imply that the module Ext* _A (X) over the Yoneda extension algebra A* is filtered by standard modules. In particular, we prove that the Yoneda extension algebra of A is also standardly stratified. This is a generalization of similar results on quasi-hereditary and on graded standardly stratified algebras.     

Contractability of l 1 -Munn algebras with applications

A Banach algebra \A is called contractible if every bounded derivation from A into any Banach A bimodule is inner. In this article we show that a l ¹ -Munn algebra LM(A, P) is contractible if and only if A is contractible and LM(A, P) is unital. As a consequence, if a semigroup algebra l ¹(S) is contractible, then S is finite. March 30, 1999