Gorenstein AC亏范畴*

作者定义了Gorenstein AC导出范畴 D^b_gac(R)并且和导出范畴作了一些比较.作者定义了Gorenstein AC奇点范畴 D^b_gacsg(R),在这个范畴中具有有限Gorenstein AC- 投射维数的模都是零对象.同时, 作者给出了由Gorenstein AC- 投射模构成的稳定范畴到奇点范畴的三角嵌入 F : GAC → D^b_sg(R) .通过作函子 F 的商引入Gorenstein AC亏范畴 D^b_gacd(R),并且给出三角等价 D^b_gacd(R) = D^b_gacsg(R)     

Singularity categories with respect to Ding projective modules

We introduce the singularity category with respect to Ding projective modules, D_(dpsg)~b(R),as the Verdier quotient of Ding derived category D_(DP)~b(R) by triangulated subcategory K~b(DP), and give some triangle equivalences. Assume DP is precovering. We show that D_(DP)~b(R)≌K~(-,dpb)(DP)and D_(dpsg)~b(R)≌D_(Ddefect)~b(R). We prove that each R-module is of finite Ding projective dimension if and only if D_(dpsg)~b(R) = 0.     

奇点模型范畴的Quillen等价

令R是左Gorenstein环.我们构造了奇点反导出模型范畴和奇点余导出模型范畴(见文[Models for singularity categories,Adv Math.,2014,254:187-232])之间的Quillen等价.作为应用,给出了投射,内射模的正合复形的同伦范畴之间的一个具体的等价■.     

商范畴的Recollement

证明了三角范畴的recollement可以自然诱导其商范畴的recollement.特别地,得到类似于群同态第二基本定理的结果,即若U是三角范畴D的局部化(或余局部化)子范畴,V是U的三角满子范畴,则U/V是D/V的局部化(或余局部化)子范畴,并且有三角等价(D/V)/(U/V)≌D/U.同理,对Abel范畴的recollement也有相应的结果.     

环的弱整体维数和CM-自由性

设环R的弱整体维数有限.本文证明R是强CM-自由的.作为应用,本文得到一些同伦范畴和相对导出范畴的三角等价和紧生成性.当R 弱整体维数不超过1时,本文完全分类了这些等价范畴中的可定义子范畴,并说明这些等价的范畴在von Neumann正则环上满足Telescope猜想.同时将一个广义Grothendieck对偶型的三角...     

单边挠对

由Beligiannis和Marmaridis引入的单边三角范畴(即左或右三角范畴)是三角范畴的自然推广. 挠理论在范畴的结构方面, 特别在导出范畴或更一般的三角范畴的研究中有着非常重要的作用. 本文引入单边三角范畴中的单边挠对概念, 讨论了这样一种单边挠理论与预三角范畴、稳定范畴以及三角范畴中相应概念的关系, 最后通过Abel范畴上的有界导出范畴D^b (A)给出例子表明存在非平凡单边挠对.     

外三角范畴中的相对合冲对象

本文研究了外三角范畴中相对合冲对象和粘合R(A’,A,A")中相对合冲对象的保持问题.利用相对同调的方法,获得了相对合冲对象的一些性质和它的等价刻画,推广了阿贝尔范畴和三角范畴中一些结果,给出了相对投射维数的一个等价刻画.主要证明了:在满足一定条件时,A’和A"中的相对合冲对象可以诱导出A中的相对合冲对象.反之,对于A中的相对合冲对象也可以诱导出A’和A"中的相对合冲对象.     

三角矩阵代数上奇点范畴和Gorenstein亏范畴的2-粘合

设■是三角矩阵代数,其中A和B是Artin代数,_AM_B是A-B-双模.本文研究了T上奇点范畴和Gorenstein亏范畴的2-粘合结构.在恰当的假设下,我们给出了T上奇点范畴和Gorenstein亏范畴的2-粘合存在的充分必要条件.     

函数芽的有限R_r~*(S;n)-决定性

光滑映射芽的有限决定性是奇点理论中一个重要专题 .对函数芽的有限决定性问题 ,主要是在右等价群及其一些子群作用下来讨论的 .本文在 [1]和 [4 ]的基础上讨论函数芽在右等价群的正规子群 R*n (S;n)作用下的有限决定性 ,并组出函数芽有限 R*r (S;n) -决定的一个充分必要条件 .     

Koszul微分分次模

引入了Koszul微分分次模的概念. 给定Koszul微分分次代数上的一个下有界的微分分次模, 如果这个模到平凡模的Ext-\!群是有界的分次空间, 则它必定包含一个微分分次子模, 其在适当的截断和移位下是Koszul微分分次模; 这样的模还可以通过一系列Koszul微分分次模来逼近(参见本文推论3.6). 设$A$是一个Koszul微分分次代数, $D^c(A)$是微分分次右$A$-\!模范畴的导出范畴中由对象$A_A$生成的满三角子范畴. 如果平凡微分分次模$k_A$落在范畴$D^c(A)$中, 则三角范畴$D^c(A)$的标准$t$-\!结构的中心, 作为Abel范畴, 与某个有限维代数上的有限生成模范畴对偶. 进一步, 可推得三角范畴$D^c(A)$等价于它的标准$t$-\!结构的中心的有界导出范畴.     

Stable t-structures and Homotopy Category of Strongly Copure Projective Modules

In this paper, we study the homotopy category of unbounded complexes of strongly copure projective modules with bounded relative homologies K~(∞,bscp)(SCP).We show that the existence of a right recollement of K~(∞,bscp)(SCP) with respect to K~(-,bscp)(SCP), K_(scpac)(SCP) and K~(∞,bscp)(SCP) has the homotopy category of strongly copure projective acyclic complexes as a triangulated subcategory in some case.     

有限生成亚投射模范畴

对一个QF环R,本文证明:其投射左R模范畴是因式分解范畴当且仅当gl.dim R≤1．进一步,若 P(_RR)＝P(R_R)＝0,则其通过左模而得到的亚 Crothendieck群与其通过右模而得到的亚Grothendieck群在同构意义下是一样的．还证明了有限生成亚投射左R－模范畴不仅是一个因式分解范畴而且是一个带积的具有小的骨架子范畴的范畴．     

Topological Hopf Algebras and Braided Monoidal Categories

The relation between a monoidal category which has an exact faithful monoidal functor to a category of finite rank projective modules over a Dedekind domain, and the category of continuous modules over a topological bialgebra is discussed. If the monoidal category is braided, the bialgebra is topologically quasitriangular. If the monoidal category is rigid monoidal, the bialgebra is a Hopf algebra.     

Localization on certain Grothendieck categories

Using categorical techniques we obtain some results on localization and colocalization theory in Grothendieck categories with a set of small projective generators. In particular, we give a sufficient condition for such category to be semiartinian. For semiartinian Grothendieck categories where every simple object has a projective cover, we obtain that every localizing subcategory is a TTF-class. In addition, some applications to semiperfect categories are obtained.     

The tensor product of Gorenstein-projective modules over category algebras

For a finite free and projective EI category, we prove that Gorenstein-projective modules over its category algebra are closed under the tensor product if and only if each morphism in the given category is a monomorphism.     

Characterizing When the Category of Gorenstein Projective Modules is an Abelian Category

We find sufficient and necessary conditions for the category of Gorenstein projective modules of an artin algebra being an abelian category, and give another proof for the Auslander–Solberg correspondence which demonstrates the concrete form of the category of Gorenstein projective modules. Then we find a characterization for this category of Gorenstein projective modules. At last we give an example of this correspondence.     

Abstract Hilbert Schemes

In analogy with classical projective algebraic geometry, Hilbert functors can be defined for objects in any Abelian category. We study the moduli problem for such objects. Using Grothendieck's general framework. We show that with suitable hypotheses the Hilbert functor is representable by an algebraic space locally of finite type over the base field. For the category of the graded modules over a strongly Noetherian graded ring, the Hilbert functor of graded modules with a fixed Hilbert series is represented by a commutative projective scheme. For the projective scheme corresponding to a suitable noncommutative graded algebra, the Hilbert functor is represented by a countable union of commutative projective schemes.     

Characterization of eventually periodic modules in the singularity categories

The singularity category of a ring makes only the modules of finite projective dimension vanish among the modules, so that the singularity category is expected to characterize a homological property of modules of infinite projective dimension. In this paper, among such modules, we deal with eventually periodic modules over a left artin ring, and, as our main result, we characterize them in terms of morphisms in the singularity category. As applications, we first prove that, for the class of finite dimensional algebras over a field, being eventually periodic is preserved under singular equivalence of Morita type with level. Moreover, we determine which finite dimensional connected Nakayama algebras are eventually periodic when the ground field is algebraically closed.