单点扩张代数与recollement

研究有限维代数的有限生成模范畴之间的recollement. 证明了: 对于3个代数A, B, C, 若$A$的模范畴允许有关于B的模范畴和C的模范畴的recollement, 则A的单点扩张代数的模范畴允许有关于B的单点扩张代数的模范畴和C的模范畴的recollement.     

rep(A_3,I,A)中的Gorenstein投射模

设A是域k上的有限维代数,(Q,I)是带关系的箭图,令Λ=AkkQ/I.Λ的模范畴Λ-Mod及有限生成模范畴Λ-mod分别与(Q,I)在A上的表示范畴Rep(Q,I,A)及有限维表示范畴rep(Q,I,A)等价.给出了范畴rep(A_3,I,A)中Gorenstein投射模的具体构造,其中(A_3,I)=3α→2β→1,I=βα.在此基础上,给出了代数A是自入射代数的一个充分必要条件.     

rep(A_3,I,A)中的Gorenstein投射模北大核心CSCD

设A是域k上的有限维代数,(Q,I)是带关系的箭图,令Λ=AkkQ/I.Λ的模范畴Λ-Mod及有限生成模范畴Λ-mod分别与(Q,I)在A上的表示范畴Rep(Q,I,A)及有限维表示范畴rep(Q,I,A)等价.给出了范畴rep(A_3,I,A)中Gorenstein投射模的具体构造,其中(A_3,I)=3α→2β→1,I=<βα>.在此基础上,给出了代数A是自入射代数的一个充分必要条件.     

量子群的基变换与范畴同构

令Ｍ是Ｚ［ｖ］的由ｖ－１和奇素数ｐ生成的理想，Ｕ是Ａ＝Ｚ［ｖ］Ｍ上相伴于对称Ｃａｒｔａｎ矩阵的量子群， Ａ－Γ是环同态， Ｕг＝ＵＡΓ［Ｕг］是Ｕг的量子坐标代数，本文建立了量子坐标代数的基变换：即在相关约束条件下有Г－Ｈｏｐｆ同构 Ａ［Ｕ］ＡГ≌Г［Ｕг］．我们证明了有限秩 Ａ自由 １型可积 Ｕ模范畴和有限秩 Ａ自由 Ａ［Ｕ］余模范畴是同构的．特别，当 Г是域时，局部有限 １型 Ｕг模范畴和Г［Ｕг］余模范畴是同构的．最后，我们还证明了在［１］中定义的诱导函子和Ｂ．Ｐａｒｓｈａｌｌ与王建磐博士在［２］中研究的诱导函子的一致性．     

两个相关代数上的一对同构模范畴

本文研究了Artin代数A与其子代数模范畴中反变有限子范畴之间的关系.利用范畴同构,获得了代数A上投射维数有限的子模范畴P∞(A)在有限生成的左A模范畴A-mod上反变有限的一个条件,推广了关于子范畴P∞(A)反变有限性的结果.     

超滤函子余代数范畴

研究了超滤函子余代数范畴set_(F_u)的乘积和余积问题.首先构造了集合乘积上的超滤,讨论集合乘积上超滤的存在形式;接着利用超滤函子的性质给出了范畴set_(F_u)的有限乘积以及任意余积构造;最后证明了范畴set_(F_u)的终对象存在.改进了Gumm关于滤子函子的研究结果,深化了相关文献关于超滤函子余代数的研究.     

外三角范畴的同调系统

在外三角范畴中,本文引入同调系统Θ(又称为Θ-系统)的概念,此概念统一了模范畴的分层系统和三角范畴的同调系统.本文证明了一个Θ-系统能够唯一地确定一个Θ-投射系统.给定一个Θ-投射系统(Θ, Q,≤),本文也证明了滤链多样性不依赖于滤链的选择,建立了所有Θ-滤对象构成的子范畴■(Θ)和模范畴mod(B)中的所有?-好模构成的子范畴之间的同构,其中B是标准分层代数.     

范畴BCI的子范畴

一切 BCI -代数和 BCI-代数间的同态映射作成范畴(?).(?)有很多子范畴.下面的一般结果使验证子范畴的工作迎刃而解。定理1 设 P 是 BCI-并数的一个性质.如果具有性质 P 的 BCI-代数存在,那么一切具有性质 P 的 BCI-代数和它们间的同态映射作成一个范畴,称为具有性质 P 的 BCI-代数范畴,且记为(?).(?)的子范畴并不仅仅由性质所产生,我们进一步有下列:定理2 (?)的一切子范畴作成一个真类。     

弱Doi—Hopf群模的半单性

在弱Hopf群余代数情形中,讨论了一簇从弱Doi-Hopf群模范畴到某个代数上的模范畴忘却函子的可分性,诱导出弱Doi-Hopf群模数据的正规化积分概念,证明了正规化积分存在性是忘却函子可分的判别准则.所得结果在弱量子Yetter-Drinfel'd群模范畴及弱相对Hopf群模范畴中有应用价值.     

顶点算子代数表示理论中的范畴和函子

本文的主要目的是,用范畴的语言对顶点算子代数理论中的一些构造加以解释,同时将Abel范畴工具应用到顶点算子代数的研究中.本文将顶点算子代数范畴中的共形同态放宽为半共形同态,同时讨论半共形同态所对应的模范畴之间的函子性质.这样陪集构造可以实现为Hom函子,并利用Hom函子讨论相关性质.作为一个应用,本文构造了Jacquet函子,并讨论了它的性质.     

Artin Algebras of Finite Type and Finite Categories of Δ-Good Modules

We give an alternative proof to the fact that, if the square of the infinite radical of the module category of an Artin algebra is equal to zero, then the algebra is of finite type by making use of the theory of postprojective and preinjective partitions. Further, we use this new approach in order to get a characterization of finite subcategories of Δ-good modules of a quasi-hereditary algebra in terms of depth of morphisms similar to a recently obtained characterization of Artin algebras of finite type.     

Coherent Functors and Covariantly Finite Subcategories

Given a locally presentable additive category A, we study a class of covariantly finite subcategories which we call definable. A definable subcategory arises from a set of coherent functors F _i on A by taking all objects X in A such that F _i X=0 for all i. We give various characterizations of definable subcategories, demonstrating that all covariantly finite subcategories which arise in practice are of this form. This is based on a filtration of the category of all coherent functors on A.     

Contravariantly Finite Subcategories and Torsion Theories

Contravariantly finite subcategories have been useful in differentaspects of representation theory (Auslander and Reiten, 1989, 1991;Auslander and Smalø, 1981) and they appear very naturally, forexample, the torsion class of a torsion theory is contravariantly finite. Inthis paper we explore further relations between contravariantly finite,resolving, subcategories and torsion theories. We study these connections inthe category of functors that vanishes on projectives. Our resultsgeneralize some theorems we obtained previously in our interpretation ofNakayamas conjecture (Martínez-Villa, 1994).     

关于余挠三元组的余星子范畴和余倾斜子范畴

设$\mathcal{A}$ 是一个Abel范畴,且 $(\mathcal{X}, \mathcal{Z},\mathcal{Y})$ 是一个完全遗传余挠三元组.介绍 $\mathcal{A}$ 的 $n$-$\mathcal{Y}$-余倾斜子范畴的定义,并给出 $n$-$\mathcal{Y}$-余倾斜子范畴的一个刻画,类似于 $n$-余倾斜模的 Bazzoni 刻画.作为应用,证明了在一个几乎 Gorenstein 环 $R$ 上, 如果 $\mathcal{GP}$ 是 $n$-$\mathcal{GI}$-余倾斜的, 那么 $R$ 是一个 $n$-Gorenstein 环, 其中 $\mathcal{GP}$ 表示 Gorenstein 投射 $R$-模组成的子范畴且 $\mathcal{GI}$ 表示 Gorenstein 内射 $R$-模组成的子范畴. 进而, 研究 任意环$R$上的$n$-余星子范畴, 以及关于余挠三元组 $(\mathcal{P}, R$-Mod, $\mathcal{I})$ 的 $n$-$\mathcal{I}$-子范畴与 $n$-余星子范畴之间的关系, 其中 $\mathcal{P}$ 表示投射左 $R$-模组成的子范畴且 $\mathcal{I}$ 表示内射左 $R$-模组成的子范畴.     

Axiomatizing subcategories of Abelian categories

We investigate how to characterize subcategories of abelian categories in terms of intrinsic axioms. In particular, we find axioms which characterize generating cogenerating functorially finite subcategories, precluster tilting subcategories, and cluster tilting subcategories of abelian categories. As a consequence we prove that any d-abelian category is equivalent to a d-cluster tilting subcategory of an abelian category, without any assumption on the categories being projectively generated.     

Remarks on Reflexive Subcategories

In this article, we study reflexive subcategories of the category of finitely generated modules over Cohen–Macaulay local rings R. One of the main results yields a complete classification of the reflexive subcategories for the case when R is a one-dimensional complete local hypersurface of finite Cohen–Macaulay representation type. The other result yields a one-to-one correspondence between the subclasses of a stable category and the reflexive subcategories over a complete local hypersurface. Then, we attempt to extend the result in Takahashi [8 Takahashi, R. (2006). Remarks on modules approximated by G-projective modules. J. Algebra 301:748–780.[Crossref], [Web of Science ®] , [Google Scholar], Proposition 4.4] to a reflexive subcategory.     

Map composition generalized to coherent collections of maps

Relation algebras give rise to partial algebras on maps, which are generalized to partial algebras on polymaps while preserving the properties of relation union and composition. A polymap is defined as a map with every point in the domain associated with a special set of maps. Polymaps can be represented as small subcategories of Set^?, the category of pointed sets. Map composition and the counterpart of relation union for maps are generalized to polymap composition and sum. Algebraic structures and categories of polymaps are investigated. Polymaps present the unique perspective of an algebra that can retain many of its properties when its elements (maps) are augmented with collections of other elements.     

Gorenstein子范畴与相对奇点范畴

令A是阿贝尔范畴, T是A的一个自正交子范畴, 且T中每个对象均有有限投射维数和内射维数. 假设左Gorenstein子范畴lG(T)等于T的右正交类,且右Gorenstein子范畴rG(T)等于T的左正交类,我们证明了Gorenstein子范畴$G(T)$等于T的左正交类与T的右正交类之交,并且证明了它们的稳定范畴三角等价于A关于T的相对奇点范畴.作为应用,令$R$是有有限左自内射维数的左诺特环, $_RC_s$是半对偶化双模,且所有内射左$R$-模的平坦维数的上确界有限, 我们证明了 若$\mbox{}_RC$有有限内射（平坦）维数且$C$的右正交类包含$R$,则存在从$C$-Gorenstein投射模与关于$C$的Bass类的交到关于$C$-投射模的相对奇点范畴间的三角等价,推广了某些经典的结果.     

关于对偶扩张代数有限维数的注记

没A是一个有限维代数，R为A的对偶扩张代数．本我们讨论R的有限维数findim R of R，证明了，在—般情况下findim R≠2findim A，这就回答了惠昌常教授所提的一个问题．     

Current algebras, highest weight categories and quivers

We study the category of graded finite-dimensional representations of the polynomial current algebra associated to a simple Lie algebra. We prove that the category has enough injectives and compute the graded character of the injective envelopes of the simple objects as well as extensions between simple objects. The simple objects in the category are parametrized by the affine weight lattice. We show that with respect to a suitable refinement of the standard ordering on the affine weight lattice the category is highest weight. We compute the Ext quiver of the algebra of endomorphisms of the injective cogenerator of the subcategory associated to an interval closed finite subset of the weight lattice. Finally, we prove that there is a large number of interesting quivers of finite, affine and star-shaped type, as well as tame quasi-hereditary algebras, that arise from our study.