除环上线性群到代数群的同态

典型群的同态问题始终是典型群理论的中心问题之一。自从1928年 O.Schreier 和B.L.van der Waerden 关于典型群的自同构的文章发表以来,经过许多数学家的努力,典型群的同构问题已经在很大范围内被解决。到本世纪七十年代人们开始考虑更一般的同态问题。A.Borel 和 J.Tits 首先确定了迷向单代数群的抽象同态,继而 B.Weisfeiler 给出了一系列非迷向单代数群的抽象同态的结果。本文解决了除环上特殊线性群及其射影群到代数群的同态问题。这是1979年在美国举行的“代数群的抽象同态会议”上 B.Weisfeiler 提出的一个公开问题。     

PARADIGM SHIFTS IN FISHERIES STOCK ASSESSMENT: FROM INTEGRATED ANALYSIS TO BAYESIAN ANALYSIS AND BACK AGAIN

ABSTRACT. I describe integrated analysis and Bayesian analysis, which have been two of the most influential paradigms in fisheries stock assessment during the last two decades of the twentieth century. These two paradigms have generally been considered complementary, rather than competing. However, recent advances in integrated analysis, including the special case of meta‐analysis, have made Bayesian analysis somewhat redundant. I describe how data used to create priors for use in Bayesian analysis can be integrated directly into the analyses. This provides a much more convenient way of accurately including the information and associated uncertainty into the analyses. I discuss how there is still a need to describe the uncertainty and suggest that research should focus on the most appropriate methods for doing this.     

初等收敛群和拟初等收敛群

作为－／R^n上的离散收敛群中的初等群的推广,本文定义了－／R^n上一般收敛群中的初等群和拟初等群,并得到了初等收敛群、拟初等收敛群和非拟初等敛群各自的一些性质和特征。     

关于T-S模的超直觉模糊群及其同态

本文研究了关于T-S模的直觉模糊正规子群、超直觉模糊群、超直觉模糊正规子群和直觉模糊商群,利用T模、S模的定义及性质,在两个经典群同态的意义下,获得了关于超直觉模糊群的同态与同构等若干结果.     

同伦群和上同调群的上乘积

<正> 在[1]中,作者研究了一个(N—1)维连通空间的同伦群和同调群的密切关系,那里所考虑的同伦群的维数是在(2N—2)以内,本文可以看成[1]的继续,我偿将考虑维数在(2N—1)以上而又在(3N—3)以下的同伦群,Betti 数;和上乘积的密切关系.我们     

NILPOTENT GROUPS AND ABELIANIZATION

We study the question of what properties of nilpotent groups are shared by their abelianizations. We identify two such properties—that of being a π-torsion group, where π is a family of primes, and that of having q^th roots, for some prime q. We use these properties to provide simplified proofs of the following theorems in the localization of nilpotent groups.

Let H, K be subgroups of the nilpotent group N and let P be a family of primes. Then [H, K] P = [H_P, K_p]

Let the group G act on the nilpotent group N. Then G acts compatibly on N_p and (Γ^G _i N)_P = Γ^G _i(N_p).

The second theorem above is then applied to the study of the localization of relative groups, in the sense of [4].     

同伦群和同调群的关系及其应用

<正> 最近几年来,关于同伦群的研究,特别是球面同化群的计算有很大的进步,但是关于更一般的空间的同伦群的计算,就作者所知道的文献来说,似乎没有相应的进展,在这一方面的工作,最早也是最主要的是 Hurewicz 定理,Serre 在[15]中利用所谓 C同构的概念,把 Hurewicz 定理推广到所谓(n-1)维 C 连通空间中,但是也和 Hure-wicz 定理一样,只能讨论 n 维同伦群和 n 维同调群的关系.张素诚,Hilton 及 Barrat     

REFLECTIVE AND QUASI-REFLECTIVE BIANCHI GROUPS

A discrete subgroup of the group of isometries of the hyperbolic space is called reflective if up to a finite index it is generated by reflections in hyperplanes. The main result of this paper is a complete classification of the reflective (and quasi-reflective) subgroups among the Bianchi groups and their extensions.     

DEFORMATIONS OF HYPERCOMPLEX STRUCTURES ASSOCIATED TO HEISENBERG GROUPS

Let X be a compact quotient of the product of the real Heisenberggroup H_4m+1 of dimension 4m + 1 and the three-dimensional realEuclidean space R³. A left-invariant hypercomplex structureon H_4m+1 x R³ descends onto the compact quotient X. The spaceX is a hyperholomorphic fibration of 4-tori over a 4m-torus.We calculate the parameter space and obstructions to deformationsof this hypercomplex structure on X. Using our calculations,we show that all small deformations generate invariant hypercomplexstructures on X but not all of them arise from deformationsof the lattice. This is in contrast to the deformations on the4m-torus.     

泛欧氏空间的Clifford群、扭群、旋群及它们的李代数

本文研究了泛欧氏空间的Clifford群、扭群、旋群,它们为Clifford代数中选出极好的一类子群.利用Clifford代数理论方法,获得了泛欧氏空间中Clifford群、扭群、旋群及其李代数的结构及它们之间的关系,并且得到了它们的李代数.     

SMOOTH POINT MEASURES AND DIFFEOMORPHISM GROUPS

Let X=R~d(d>1).Consider the unitary representations of Diff(X)given by quasi-invariant measures under the action of Diff(X).The author proposes smooth point measuresas generalization of Poisson point measures and proves that every smooth point measure isquasi-invariant under the action of Diff(X)and if {U_g~i},i=1,2,are the unitary represen-tations of Diff(X)given by the smooth point measures μ_i,i=1,2,respectively,then {U_g~1}is unitarily equivalent to {U_g~2} iff μ_1 is equivalent to μ_2 as measure.