Fibonacci代数的Hochschild上同调群

设∧d是Fibonacci代数,基于对Bardzell极小投射双模分解的细致分析,用组合的方法清晰地计算了Fibonacci代数∧d的各阶Hochschild上同调群的维数.     

斜群代数的截断代数和平凡扩张

主要讨论有限群G=N×MSL(3,C)的McKay箭图,及其对应的斜群代数∧V*G的截断箭图和截断代数的性质,证明了当3|(n+1),3|r时,其特殊截断代数的平凡扩张与斜群代数∧V*G同构.     

环的Galois,分离和Frobenius扩张

设∧是其中心Ｃ＿∧上的有限维单代数，Ｆ是满足Ｃ＿∧的∧的子环，Ｇ是保持Γ的元素不变的∧的自同构的有限群．本文证明：若∧／Γ是Ｇ－Ｇａｌｏｉｓ扩张，则在∧中的中心化子△是Ｃ＿Γ一分离代数且∧／Γ是Ｆｒｏｂｅｎｉｕｓ扩张，这里Ｃ＿Γ是Γ的中心．     

扭平凡扩张与表示维数

设k是代数闭域,∧是k上基本有限维连通Koszul自入射代数.本文首先证明:如果∧满足有限生成(FG)假设,那么存在∧的k-代数自同构σ0使得关于∧-双模D∧~(σ0)的扭平凡扩张T(∧~(σ0))=∧×D∧~(σ0)亦满足FG假设.由此得到,在∧满足FG假设的条件下,(1)T(A~(σ0))的表示维数大于等于∧的复杂度加2;(2)设G是∧的k-代数自同构群Aut_k(∧)的有限子群,且其阶在∧中可逆.如果对于任意的g∈G都有σ0g=gσ0,那么斜群代数∧*G的扭平凡扩张代数T((∧*G)~(σ0))的表示维数大于等于∧的复杂度加2.     

扭平凡扩张与表示维数北大核心CSCD

设k是代数闭域,∧是k上基本有限维连通Koszul自入射代数.本文首先证明:如果∧满足有限生成(FG)假设,那么存在∧的k-代数自同构σ0使得关于∧-双模D∧^(σ0)的扭平凡扩张T(∧^(σ0))=∧×D∧^(σ0)亦满足FG假设.由此得到,在∧满足FG假设的条件下,(1)T(A^(σ0))的表示维数大于等于∧的复杂度加2;(2)设G是∧的k-代数自同构群Aut_k(∧)的有限子群,且其阶在∧中可逆.如果对于任意的g∈G都有σ0g=gσ0,那么斜群代数∧*G的扭平凡扩张代数T((∧*G)^(σ0))的表示维数大于等于∧的复杂度加2.     

一类扩张仿射李代数上的非交换Poisson代数

讨论了以量子环面为坐标代数,零度v的A型扩张仿射李代数s1_N(CQ)上的非交换的Poisson代数,证明了它的导出李子代数上的结合乘积是平凡的.同时,给出了标度元素的结合积的形式.     

FI代数的导出序结构的一些性质

深入研究F I代数的与其导出序结构相关的一些性质。特别地,分别得到了在F I代数(L,→,0)中下列各式之一成为恒等式的若干条件:(1)(x∨y)→z=(x→z)∧(y→z);(2)z→(x∨y)=(z→x)∨(z→y);(3)(x∧y)→z=(x→z)∨(y→z);(4)z→(x∧y)=(z→x)∧(z→y)。     

多值逻辑代数的一个注记

给出多值逻辑代数的一条性质（x-y）∧（y-x）=0的新证明．     

关于格蕴涵代数公理的一个注记

设在一个非空集合L上有一个二元运算→和两个零元运算O与I，除此之外没有其它已知的代数结构，利用这三个运算可以在L上定义一个一元运算′和两个二元运算∨和∧（定义2．1）。本文证明了只要这些运算满足格蕴涵代数的公理（不包括有余格的公理），（L，∨，∧，′）就是一个有泛界O，I的有余格（定理2．2）。因此在定义格蕴涵代数时可以在一个没有任何代数结构的非空集合上定义蕴含运算而不必在一个有泛界的有余格上定义蕴含运算，而且在这两种定义方式中蕴含运算所满足的条件是相同的。     

具有Heyting结构的Ockham代数

引入一个具有Heyting结构Ockham代数,简称HO-代数．所谓HO-代数,是指具有（2,2,2,1,0,0）类型的代数（L;∧,∨,→,f,0,1）．其中（L;f）是Ockham代数,（L;→）是Heyting代数,且运算f和→由恒等式f（x→y）=f^2（x）∧f（y）与f（x）→y=f^2（x）∨y所连结．主要讨论了HO-代数的同余关系的性质．并刻画了其次直不可约代数的某些性质．     

The Socle and Semisimplicity of a Kumjian–Pask Algebra

The Kumjian–Pask algebra KP(Λ) is a graded algebra associated to a higher-rank graph Λ and is a generalization of the Leavitt path algebra of a directed graph. We analyze the minimal left ideals of KP(Λ), and identify its socle as a graded ideal by describing its generators in terms of a subset of vertices of the graph. We characterize when KP(Λ) is semisimple, and obtain a complete structure theorem for a semisimple Kumjian–Pask algebra. As a consequence of this structure theorem, every semisimple Kumjian–Pask algebra can be obtained as a Leavitt path algebra of a directed graph.     

Vertex Algebra Sheaf Structure on Torus

In this paper, we first give a 1-1 corresponds between torus C/Λ and cubic curve C in P_C~2. As complex manifold, they are isomorphic, therefore we can treat C/Λ as a variety and construction a vertex algebra sheaf on it.     

Cluster tilting for higher Auslander algebras

The concept of cluster tilting gives a higher analogue of classical Auslander correspondence between representation-finite algebras and Auslander algebras. The n-Auslander–Reiten translation functor τn plays an important role in the study of n-cluster tilting subcategories. We study the category Mn of preinjective-like modules obtained by applying τn to injective modules repeatedly. We call a finite-dimensional algebra Λ n-complete if for an n-cluster tilting object M. Our main result asserts that the endomorphism algebra EndΛ(M) is (n+1)-complete. This gives an inductive construction of n-complete algebras. For example, any representation-finite hereditary algebra Λ(1) is 1-complete. Hence the Auslander algebra Λ(2) of Λ(1) is 2-complete. Moreover, for any n?1, we have an n-complete algebra Λ(n) which has an n-cluster tilting object M(n) such that Λ(n+1)=EndΛ(n)(M(n)). We give the presentation of Λ(n) by a quiver with relations. We apply our results to construct n-cluster tilting subcategories of derived categories of n-complete algebras.     

二元外代数的Z_n-Galois覆盖代数的Hochschild(上)同调群

设Λ是特征不整除n的域k上的二元外代数,■是Λ的Zn-Galois覆盖代数.首先构造了■的极小投射双模分解,并由此清晰地计算了■的各阶Hochschild同调和上同调群的维数;并且在域的特征为零时,计算了■的循环同调群的维数.     

一类量子Koszul 代数的Hochschild 上同调

本文利用组合的方法, 详细地计算了一类量子Koszul 代数Λ_q (q ∈ k \{0}) 的各阶Hochschild 上同调空间的维数, 清晰地刻划了代数Λ_q 的Hochschild 上同调的cup 积, 确定了代数Λ_q 的Hochschild上同调环HH^*(Λ_q) 模去幂零元生成的理想N 的结构, 证明了当q 为单位根时, HH^*(Λ_q)/N 作为代数不是有限生成的, 从而为Snashall-Solberg 猜想(即HH^*(Λ)/N 作为代数是有限生成的) 提供了更多反例.     

Representations of Extended Affine Lie Algebras Coordinatized by Certain Quantum Tori

An irreducible representation of the extended affine Lie algebra of type A _n-1 coordinatized by a quantum torus of variables is constructed by using the Fock space for the principal vertex operator realization of the affine Lie algebra .     

The Coradical Filtration for Drinfeld Double Ringel-Hall Algebras

Abstract

Let 𝒟(Λ) be the Drinfeld double Ringel-Hall algebra with Λ being any finite dimensional hereditary algebra over a finite field k. We determine the coradical filtration for 𝒟(Λ). As an application, we describe the group of Hopf algebra automorphisms of the Drinfeld double Ringel composition algebra of Λ.     

Rank one quotients of vector groups

ABSTRACT

In this paper we study the possible torsion in even-dimensional higher class groups Cl _2n (Λ)(n ≥ 1) of an order Λ in a semisimple algebra A over a number field F with a ring of integers 𝒪 _F . We show that for certain orders, called generalized Eichler orders, bip-torsion in Cl _2n (Λ) can only occur for primes p dividing prime ideals ? of 𝒪 _F , at which Λ is not maximal. In particular, the results apply to Eichler orders in quaternion algebras and to hereditary orders.     

Sequences of Hopf-Swan subgroups

Let l be an odd prime which satisfies Vandiver's conjecture, let n?1 be an integer, and let K=Q(ζn) where ζn is a primitive lnth root of unity. Let Cl denote the cyclic group of order l. For each j, j=1,…,ln−1, there exists an inclusion of Larson orders in KCl: Λj−1⊆Λj and a corresponding surjection of Hopf-Swan subgroups T(Λj−1)→T(Λj). For the cases n=1,2 we investigate the structure of various terms in the sequence of Hopf-Swan subgroups including the Swan subgroup T(Λ₀).