具拟不变测度群胚流上的交叉积

设G为第二可数局部紧有Haar系{λu}的群胚,A为G上左不变作用的交换群,则我们有C-动力系统（C（G）,A,β）．本文我们研究具有一定性质的拟不变测度,用此测度,得到了一些有关群胚C-代数及交叉积的重要结果,     

约化Banach 代数的谱不变性和双曲群

主要研究了可数离散群的性质 SRD, 并证明了具有性质 SRD的群上的速降函数全体组成的空间是约化Banach代数 谱不变的稠密子代数. 最后作为例子给出了双曲群具有性质 SRD.     

群元值测度的一个定义和一些性质

文中给出了定义在第二可数完备布尔代数上,取值于半序交换群内的群元值测度的一个定义和一些性质.     

具拟不变测度群胚流上的Toeplitz代数

设G为第二可数群胚,具有Haar系{λ^n},R为实数群,左不变作用在G上。本文我们自然地（作为[3]中概念的推广）引进两类Toeplitz代数（对应于一拟不变测度）,即小和大Toeplitz代数,并且得到了小Toeplitz代数的同构定理及k群。     

用子群计数刻画有限p群

本文利用子群计数刻画了型不变量为(p~k,p,p,…,p)的交换p群以及亚循环的内交换p群(其中p为奇素数).     

关于广群的顺从性

对第二可数局部紧广群Ｇ，若Ｇ是测度点点顺从的，则，反之，若Ｇ满足ｉ）ｕ→λｕ（Ｏ）连续，为相对紧开集；或ｉｉ）λｕ（Ｋ∩Ｋｃ）＝０，Ｋ为Ｇ中紧集；则若，对任意拟不变概率测度μ，存在η∈Ｃｃ（Ｇ），‖ηｎ‖Ｌ２（Ｇ，ν）＝１，使得∫ｆ（ｘ）ηｎ·ηｎ（ｘ）ｄν０（ｘ）→∫ｆ（ｘ）ｄν０（ｘ）     

内交换的capable p-群性质研究

研究了内交换p-群G是capable群需要满足的条件,得到了这类群是capable群的充要条件.并由内交换p-群G构造得到了群H,使得H满足HH/Z(H)≌G.     

具有性质Γ的有限von Neumann代数的交叉积北大核心CSCD

令M为可分的Ⅱ_(1)型von Neumann代数.我们证明了,如果M具有性质Γ,G为可数顺从群且α是G在M上保迹的真外作用,则交叉积M■αG为具有性质Γ的Ⅱ_(1)型von Neumann代数.     

csf可数空间的注记

讨论csf可数空间的性质,把csf可数空间刻画为度量空间的映像,同时探讨了伪紧的csf可数空间的第一可数性质,推广了Arhangel’skiˇ?关于度量空间伪开s映像的结果,证明了正则伪紧的仿拓扑群是可度量化的当且仅当它是csf可数的Fr′echet空间.     

有限群的某些定理

本文给出了有限群的如下结果：１）成为可解群与超可解群的条件；２）推广了Ｉｔｏ定理，３）超可解且内幂零的群结构。     

A CHARACTERIZATION OF LOCALLY COMPACT INNER AMENABLE GROUPS

For locally compact groups G, Kuan Yuan studied a notion of inner amenability groups, that is, if there exists an inner invariant mean on G. In this article, among other things, the author investigates the inner amenability on a locally compact group G. The author gives sufficient conditions and some necessary conditions about G to have an inner invariant mean.     

The depth invariant for group actions on countable phase spaces

The construction of the depth of a countable symbolic system, which was studied earlier by the author for actions of the group , is generalized to the case of an arbitrary finitely generated Abelian group action. A new property, which is called the uniformity of the depth, is studied. The depth, which takes values in the set of at most countable ordinals, is a topological invariant of countable symbolic systems. In the paper we describe the set of possible values of the depth invariant and the method of constructing dynamical systems with an arbitrary admissible depth. Translated fromMatematicheskie Zametki, Vol. 65, No. 6, pp. 893–907, June, 1999.     

Homogeneous and strictly homogeneous criteria for partial structures

The Galois closure on the set of relations invariant to all finite partial automorphisms (automorphisms) of a countable partial structure is established via quantifier-free infinite predicate languages (infinite languages with finite string of quantifiers respectively). Based on it the homogeneous and strictly homogeneous criteria for a countable partial structure as well as an ultrahomogeneous criterion for a countable relational structure are found. Next it is shown that infinite languages with a finite string of quantifiers cannot determine the corresponding Galois closure for relations invariant to all automorphisms of an uncountable partial structure.     

可数sofic群的等距线性作用的维数

我们对复Banach空间上的可数sofic群的等距线性作用提出了一种新的维数，推广了复Banach空间上的可数顺从群的等距线性作用的Voiculescu维数，并且在可数sofic群的情形回答了Gromov的一个问题.     

Foliations of polynomial growth are hyperfinite

We define a class of equivalence relations with polynomial growth and show that such relations always support finite invariant measures and are hyperfinite. In particular, foliations of polynomial growth define hyperfinite equivalence relations with respect to any family of finite invariant measures on transversals. We also extend a result of Dye for countable groups to show that if a locally compact second countable groupG acts freely on a Lebesgue spaceX with finite invariant measure, so that the orbit relation onX is hyperfinite, thenG is amenable.     

On asymptotic dimension of countable Abelian groups

We compute the asymptotic dimension of the rationals given with an invariant proper metric. We also show that a countable torsion Abelian group taken with an invariant proper metric has asymptotic dimension zero.     

On diagonal actions of branch groups and the corresponding characters

We introduce notions of absolutely non-free and perfectly non-free group actions and use them to study the associated unitary representations. We show that every weakly branch group acting on a regular rooted tree acts absolutely non-freely on the boundary of the tree. Using this result and the symmetrized diagonal actions we construct for every countable branch group infinitely many different ergodic perfectly non-free actions, infinitely many II₁-factor representations, and infinitely many continuous ergodic invariant random subgroups.     

Factoring positive operators on reproducing kernel Hilbert spaces

We characterize when positive operators can be factored by analytic Toeplitz type operators. As a corollary, we give an operator theory characterization of those invariant subspaces of doubly commuting unilateral shifts, which are generated by a single inner function on the bidisk. The last result extends to shifts of arbitrary (countable) multiplicity.     

On Finite Nonabelian Loop Capable Groups

We say that groups, which are isomorphic to inner mapping groups of finite loops, are loop capable. Let p and q be distinct prime numbers, S a nonabelian group of order pq, and C a finite nontrivial cyclic group such that gcd (|S|, |C|) = 1. We show that the group S × C is not loop capable.     

Stationary probability measures and topological realizations

We establish the generic inexistence of stationary Borel probability measures for aperiodic Borel actions of countable groups on Polish spaces. Using this, we show that every aperiodic continuous action of a countable group on a compact Polish space has an invariant Borel set on which it has no σ-compact realization.