Cleft扩张的余挠维数

众所周知,如果扩张AB是cleft的,则B≌A#_σH.本文主要讨论B和A的余挠维数之间的关系,得出结论LCD(B)■LCD(A)+RD(H),从而推广了群环余挠维数的结论.作为主要结果的应用,还给出了几个使得LCD(B)=LCD(A)的条件.     

环的余挠维数

研究了Milnor方图上的余挠维数,然后探讨了环的余挠维数和整体维数,弱整体维数之间的关系和差别.证明了一个Prüfer整环的余挠维数不超过1当且仅当它是整体维数不超过2的Matlis整环.     

有限内射维数的余倾斜余模(英文)

本文中,受C.Nastasescu etc.和Y.Miyashita思想的影响,定义了余代数的余倾斜余模,研究得出有限内射维数的余倾斜余模的一些结论.     

Gorenstein平坦(余挠)维数和Hopf作用

设H是域k上的有限维Hopf代数,A是左H-模代数.本文研究了Gorenstein平坦（余挠）维数在A-模范畴和A#H-模范畴之间的关系.利用可分函子的性质,证明了（1）设A是右凝聚环,若A#H/A可分且φ：A→A#H是可裂的（A,A）-双模同态,则l：Gwd（A）=l：Gwd（A#H）;（2）若A#H/A可分且φ：A→A#H是可裂的（A,A）-双模同态,则l：Gcd（A）=l：Gcd（A#H）,推广了斜群环上的结果.     

关于伪紧余代数、余挠对和弦余代数

本文利用箭图和拓扑伪紧空间研究了K-余代数及其表示.定义了域K上的伪紧K-余代数,研究了伪紧K-余代数和K-代数范畴之间的关系,研究了余挠对和余模逼近,描述了余倾斜余挠对.通过有限维的支撑子余代数和基本的路余代数研究了弦余代数.     

平衡对和完备余挠对

通过讨论平衡对、相对于平衡对的特殊逼近和相对于平衡对的余挠对之间的关系,给出了它们的一些性质,并得到了相对完备余挠对的等价刻画.     

有限群分次环上的余挠对研究

本文研究了余挠对在有限群分次和非分次情况下的联系.利用分次理论以及相对同调,我们首先研究了R是任意环G是有限群的情况下,余挠对在R-模范畴以及斜群环S=R*G-模范畴之间的关系;然后我们研究了R-gr范畴中刚性余挠对的等价刻画,同时给出了余挠对在R-gr范畴与R-模范畴之间的关系,其中R是G分次环,群G是有限群且|G|^-1∈R.     

正合范畴中的复形、余挠对及粘合

作者在弱幂等完备的正合范畴(A,E)中引入了复形的新的定义,并且证明了E-正合复形的同伦范畴Kex(E)是同伦范畴KE(A)的厚子范畴.给定(A,E)中的余挠对(x,y),定义了正合范畴(CE(A),C(E))中的两个余挠对((x)E,dg(y)E)和(dg(x)E,(y)E),并且证明了当A是可数完备时,CE(A)中...     

ω-k-挠自由模与ω-左逼近维数

引进了相对于一个双模ω的ω-k-挠自由模,用左addR ω-逼近刻画了ω-k-挠自由模. 引进了ω-左逼近维数,描述了是k-挠自由模的k-合冲模的形式.     

ω-k-挠自由模与 ω-左逼近维数

引进了相对于一个双模 ω-的ω-k-挠自由模,用左add_R ω-逼近刻画了ω-k-挠自由模.引进了 ω-左逼近维数,描述了是k-挠自由模的k-合冲模的形式.     

关于半对偶化模的Gorenstein模的稳定性

本文研究了相对于半对偶化模C的Gorenstein模（即Gorenstein C-投射模,Gorenstein C-内射模和Gorenstein C-平坦模）的稳定性的问题.利用同调的方法,获得了Gorenstein C-投射（C-内射,C-平坦）模具有很好的稳定性的结果,推广了Gorenstein投射（内射,平坦）模具有很好的稳定性的结果.     

F-Continuous Graphs

For a nontrivial connected graph F, the F-degree of a vertex in a graph G is the number of copies of F in G containing . A graph G is F-continuous (or F-degree continuous) if the F-degrees of every two adjacent vertices of G differ by at most 1. All P₃-continuous graphs are determined. It is observed that if G is a nontrivial connected graph that is F-continuous for all nontrivial connected graphs F, then either G is regular or G is a path. In the case of a 2-connected graph F, however, there always exists a regular graph that is not F-continuous. It is also shown that for every graph H and every 2-connected graph F, there exists an F-continuous graph G containing H as an induced subgraph.     

Relative homology and the structure of relative approximations

The structure of rightF-^⊥ T-approximations of any finitely generated module over an artin algebra Λ is given, relative to an additive subbifunctorF of Ext _Λ ¹ (-, -) and anF-cotilting moduleT.     

广义强向量拟均衡问题组解的存在性

本文研究了一类集值广义强向量拟均衡问题组解的存在性问题.利用集值映射的自然拟C-凸性和集值映射的下(-C)-连续性的定义和Kakutani-Fan-Glicksberg不动点定理,在不要求锥C的对偶锥C~*具有弱*紧基的情况下,建立了该类集值广义强向量拟均衡问题组解的存在性定理.所得结果推广了该领域的相关结果.     

Results on <Emphasis Type="Italic">F</Emphasis>-continuous graphs

For any nontrivial connected graph F and any graph G, the F-degree of a vertex v in G is the number of copies of F in G containing v. G is called F-continuous if and only if the F-degrees of any two adjacent vertices in G differ by at most 1; G is F-regular if the F-degrees of all vertices in G are the same. This paper classifies all P ₄-continuous graphs with girth greater than 3. We show that for any nontrivial connected graph F other than the star K _1,k , k ⩾ 1, there exists a regular graph that is not F-continuous. If F is 2-connected, then there exists a regular F-continuous graph that is not F-regular.      

A new look at KK-theory

We describe the Kasparov group KK(A, B) as the set of homotopy classes of homomorphisms from an algebra qA associated with A into K B. The algebra qA consists of K-theory differential forms over A. Its construction is dual to that of M ₂(A). The analysis of qA and of its interplay with M ₂(A) gives the basic results of KK-theory.Partially supported by NSF.     

The Proof of Inseparable Prime AW^＊—Algebras Being Primitive C^＊—Algebras

The relation between the inseparable prime C^*-algebras and primitive C^*-algebras is studied,and we prove that prime AW^*-algebras are all primitive C^*-algebras.     

THE FUNDAMENTAL GROUP OF THE AUTOMORPHISM GROUP OF A NONCOMMUTATIVE TORUS

Assume that each completely irrational noncommutative torus is realized as an inductive limit of circle algebras, and that for a completely irrational noncommutative torus Aw of rank m there are a completely irrational noncommutative torus Aρ of rank m and a positive integer d such that tr(Aw)=1/d.tr(Aρ).It is proved that the set of all C^*-algebras of sections of locally trivial C^*-algebra bundles over S^2 with fibres Aω has a group sturcture,denoted by π1^s(Aut(Aω)),which is isomorphic to Zif Ed&gt;1 and {0} if d&gt;1.Let Bcd be a cd-homogeneous C^*-algebra over S^2&#215;T^2 of which no non-trivial matrix algebra can be factored out.The spherical noncommutative torus Sρ^cd is defined by twisting C^*(T2&#215;Z^m-2) in Bcd &#215;C^*(Z^m-3) by a totally skew multiplier ρ on T^2&#215;Z^m-2。It is shown that Sρ^cd&#215;Mρ∞ is isomorphic to C(S^2)&#215;C^*(T^2&#215;Z^m-2,ρ）&#215; Mcd(C)&#215;Mρ∞ if and only if the set of prime factors of cd is a subset of the set of prime factors of p.