关于交换环上带正则基的Hopf-Galois扩张的同构类

本文考虑交换环上带正则基的Ｈｏｐｆ－Ｇａｌｏｉｓ扩张的刻划及其同构类集合的结 构．主要结论是：当Ｂ为一交换环、Ｈ为余交换的有限Ｈｏｐｆ时,上述同构类集合 构成群并与 Ｌ~＊＝（ＢＨ）~＊的 ２次上同调群 Ｈ~２（Ｌ~＊, Ｕ）同构．     

有限交换环上极限线性群的Sylowp—子群

本文给出了有限交换局部环Ｒ上无限线性群ＧＬ（Ｒ）＝∪ｎＧＬｎＲ的Ｓｙｌｏｗｐ－子群的形式．令Ｍ是有限交换局部环Ｒ的唯一极大理想，ｋ＝Ｒ／Ｍ为Ｒ的剩余类域．用Ｘ（ｋ）表示ｋ的特征，并假定Ｐ与ｘ（ｋ）互素．作者证明了：ＧＬ（Ｒ）的任一Ｓｙｌｏｗｐ－子群Ｓ或者同构于的可数无限直积与Ｐ（ｊ）的无限直积的直积（当Ｐ≠２或Ｐ＝２，Ｘ（ｋ）β≡１（ｍｏｄ４））或者同构于Ｐｉ的无限直积与Ｐ（ｊ）的无限直积的直积（当Ｐ＝２，Ｘ（ｋ）β≡３（ｍｏｄ４）），这里，只是ＧＬ（ｅｐｉ）Ｒ（分别地，ＧＬ（２ｒｉ）Ｒ）的Ｓｙｌｏｗｐ－子群，Ｐ（ｊ））同构于Ｐ＝∪ｉ∈Ｉｐｉ，Ｉ是可数集．     

关于Levesque的信念逻辑的完备性

Ｈ．Ｊ．Ｌｅｖｅｓｑｕｅ最近为了研究非单调推理提出了含有两个模态词Ｂ，Ｎ的信念逻辑系统，并猜想它是完备的．本文提出了Ｔ~＊－集合的概念，并证明一句子集合如果是Ｔ~＊－集合，那么是可满足的．本文的定理是［１］中定理Ａ２的推广．并得到［１］中定理Ａ．２的一个简单的证明．     

关于交换环上带正则基的Hopf-Glois扩张的同构类

本文考虑交换环上带正则基的Hopf-Glois扩张的刻划及其同构类集合的结构.主要结论是:当B为一交换环、H为余交换的有限Hopf时,上述同构类集合构成群并与L*=(BH)*的2次上同调群H2(L*,U)同构.     

论优化问题的公理方法（Ⅰ）

π－簇表示论域Ω上具有性质π的集合簇：≠；当Ａ，Ｂ∈，Ｂ∈，ＸＡ，总有Ｘ，Ａ∪Ｂ∈．定义２在π－簇上，＊是优化算子，如果公理１Ａ对应唯一的子集合Ａ＊．写Ａ＝Ａ＊∪，Ａ＊∩Ａ＝；公理２；．定义３在定义２中，还满足公理３若ＡＣ，则ＡＣ；公理４（Ａ＊∪Ｂ）＊（Ａ∪Ｂ），则说算子＊是上的第一类优化算子．对此，建立了两个优化原理，还给出了几个关于这种算子＊的例子．     

G-旋模型场代数中的对偶定理

设Ｇ是有限群，　Ｈ是Ｇ的子群，Ｄ（Ｇ）为Ｇ的Ｄｏｕｂｌｅ代数，　Ｆ是　Ｇ－旋模型所对应的场代数．　本文考虑Ｄ（Ｇ）的Ｈｏｐｆ子代数Ｄ（Ｈ），证明了Ｆ的Ｄ（Ｈ）不变子空间ＡＨ是Ｃ＊－代数．Ｄ（Ｈ）存在Ｃ＊－表示，使得Ｄ（Ｈ）和ＡＨ互为换位子．     

Hopf Galois扩张与Hopf模结构定理

设Ｈ是域ｋ上任意的Ｈｏｐｆ代数。本文首先讨论了右Ｈ＿扩张Ａ／Ａ￣（ｃｏＨ）与Ｈｏｐｆ模范畴，给出了Ａ／Ａ￣（ｃｏＨ）为右Ｈ－Ｇａｌｏｉｓ扩张的充分必要条件和Ｈｏｐｆ模范畴满足结构定理的若干等价条件．然后我们讨论了不可约作用与除环的Ｇａｌｏｉｓ扩张．     

Groupoid的诱导表示

设Ｇ为第二可数局部紧有Ｈａａｒ系的Ｇｒｏｕｐｏｉｄ， Ｈ为子Ｇｒｏｕｐｏｉｄ闭于Ｇ，则可得Ｇｒｏｕｐｏｉｄ　Ｈ＼Ｇ２，我们证明了Ｃ＊（Ｈ）与Ｃ＊（Ｈ＼Ｇ２）是Ｍｏｒｉｔａ等价的，从而回答了［１］中的问题．利用此非本原双模及定义Ｃ＊（Ｇ）到Ｍ（Ｃ＊（Ｈ＼Ｇ２））的映射，得到了由Ｃ＊（Ｈ）到Ｃ＊（Ｇ）的诱导表示．特别在群丛情形，我们定义了Ｃ＊（Ｈ）→Ｍ（Ｃ＊（Ｇ））的映射，并具体得到了诱导表示的积分形式的表达式．     

交换的实W~*-代数

本文指出，交换的（复）Ｗ 代数的大部分结果对于实情形仍然成立，自然有周期为２同胚的差别．此外，不同于复情形，可分实Ｈｉｌｂｅｒｔ空间中不包含任何极小投影的交换实ＶＮ代数同构于Ｌ∞（［０，１］），Ｌ∞ｒ（［０，１］）或Ｌ∞（［０，１］）Ｌ∞ｒ（［０，１］）．     

Hopf代数余作用

对于Ｈｏｐｆ代数Ｈ上的余模代数Ａ,当Ｈ是有限维或幺模（ｕｎｉｍｏｄｕｌａｒ）时,存在由交叉积Ａ＃Ｈ^＊ｒａｔ和余不变子代数Ａ^ｃｏＨ构成的Ｍｏｒｉｔａ Ｃｏｎｔｅｘｔ．本文论证了对于任意的Ｈｏｐｆ代数Ｈ,结果仍是成立的     

On the isomorphic classes of hopf-galois extensions with normal bases over a commutative ring

In this paper we consider the isomorphic classes of H-Galois extensions with the normal basis property over a fixed commutative ring B for a finite Hopf algebra H. The result is that when H is cocommutative, then the above isomorphic classes and the 2-nd cohomology group H ²(L*, U) are isomorphic as groups under the product defined in this paper, where L=B∝H, L*=Hom _B (L, B). Supported by the NNSF of China     

NON-ISOMORPHIC GROUPS WITH ISOMORPHICSPECTRAL TABLES AND BURNSIDE MATRICES

ＮＯＮ－ＩＳＯＭＯＲＰＨＩＣＧＲＯＵＰＳＷＩＴＨＩＳＯＭＯＲＰＨＩＣＳＰＥＣＴＲＡＬＴＡＢＬＥＳＡＮＤＢＵＲＮＳＩＤＥＭＡＴＲＩＣＥＳ￥Ｗ．ＫＩＭＭＥＲＬＥ；Ｋ．Ｗ．ＲＯＧＧＥＮＫＡＭＰ（ＭａｔｈｅｍａｔｉｓｃｈｅｓｉｎｓｔｉｔｕｔＢ，Ｕｎｉｖｅｒｓ...     

关于Grothendieck群的几点注记

作者在本文中围绕Ｇｒｏｔｈｅｎｄｉｅｃｋ群对几个问题进行了讨论，主要结果有：１．一切有限生成Ｒ－模的同构类作成一个集合；２．在任意由Ｒ－模作成的集合中稳定同的关系是合同关系；３．Ｇｒｏｔｈｅｎｄｉｅｃｋ群的同构不变性成立。     

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.     

OPTIMAL ERROR ESTIMATES FOR NEDELEC EDGE ELEMENTS FOR TIME-HARMONIC MAXWELL'S EQUATIONS

In this paper, we obtain optimal error estimates in both L^2-norm and H（curl）-norm for the Nedelec edge finite element approximation of the time-harmonic Maxwell＇s equations on a general Lipschitz domain discretized on quasi-uniform meshes. One key to our proof is to transform the L^2 error estimates into the L^2 estimate of a discrete divergence-free function which belongs to the edge finite element spaces, and then use the approximation of the discrete divergence-free function by the continuous divergence-free function and a duality argument for the continuous divergence-free function. For Nedelec＇s second type elements, we present an optimal convergence estimate which improves the best results available in the literature.     

Uniserial modules: sums and isomorphisms of subquotients

Let R be an associative ring with 1. A left R module M is uniserial i f the lattice L(M) of its submodules is totally ordered under inclusion. We give an example of a uniserial module M with the property of having two submodules 0 < H < K < M such that M is isomorphic to K/H (we call a module M with this property shrinkable). Then we give an example of a uniserial module M isomorphic to all its nonzero quotients M/N, N<M, and with L(M) isomorphic to ω²+1; this solves a problem of Hirano and Mogami [7]. Finally we show that for uniserial modules the property of being shrinkable is connected to the problem of deciding whether a module, which is both a homomorphic image of a finite direct sum of uniserial modules and a submodule of a finite direct sum of uniserial modules, is a finite direct sum of uniserial modules     

Some generalizations of torsion-free Crawley groups

In this paper we investigate two new classes of torsion-free Abelian groups which arise in a natural way from the notion of a torsion-free Crawley group. A group G is said to be an Erd?s group if for any pair of isomorphic pure subgroups H,K with G/H ? G/K, there is an automorphism of G mapping H onto K; it is said to be a weak Crawley group if for any pair H,K of isomorphic dense maximal pure subgroups, there is an automorphism mapping H onto K. We show that these classes are extensive and pay attention to the relationship of the Baer-Specker group to these classes. In particular, we show that the class of Crawley groups is strictly contained in the class of weak Crawley groups and that the class of Erd?s groups is strictly contained in the class of weak Crawley groups.     

李超代数的泛包络代数同构问题

李超代数的一个性质P叫做关于泛包络代数的不变量,如果对于任意李超代数L,H,只要L具有性质P,并且泛包络代数U(L)和U(H)作为结合超代数是同构的,那么H亦具有性质P.通过讨论李超代数关于泛包络代数的不变量证明了:如果L的幂零长度不超过2,那么L和H是同构的.     

UHF-ALGEBRAS AND *-ISOMORPHISMS

The following problem is discussed: If μ is an AF-algebra, A and B are two C-algebras, x(A) and x(B) are the unit balls of μ A and μ B respectively, and there is an affine isomorphism from X(A) onto x(B), when are A and B isomorphic? This problem was inspired by K-theory of C*-algebras. If μ is a UHP-algebra of type {m~p}, an orientation on x(A) and x(B), i. e., an action of the special group of μ, is introduced. Then it is obtained that if the affine isomorphism commutes with the group action then A and B are isomorphic.