四元数半空间上模形式的维数公式 *

利用Selberg迹公式导出次数为 2的四元数半空间上尖点形式的一个维数公式 ,并计算出一些共轭类对维数公式的贡献 ,同时还得到模群共轭类划分的一些结果 .     

k个矩阵的核子空间的和的维数

利用齐次线性方程组的解的表达式及分块矩阵的一个秩等式,得出了k个矩阵的核子空间的和的维数的一个公式,它推广了维数公式.并给出了这个公式的几个应用.     

有限维线性空间上子空间并的性质的一个注记

对于特征为零的域上的有限维线性空间的子空间的并,我们知道下述性质:有限个互不包含的非平凡子空间的并不是原来的线性空间.一方面,本文通过介绍有限维线性空间中任一子空间与齐次线性方程组解子空间的关系,及商空间的维数公式,给出了上述性质的一个改进证明.另一方面,本文把仿射簇的概念和子空间联系起来,并根据仿射簇的一个简单性质,给出了上述性质的另一个更为简洁的证法.     

拓扑线性空间的泛函维数

<正> 文献[1]提出了泛函维数的概念,并对可列希尔伯特空间进行了讨论.它指出,泛函维数有限的可列希氏空间是核空间. 本文对泛函维数进行了进一步探讨,获得如下结果:     

研究二元样条空间维数的Blossoming方法

本文综述了研究二元样条的Ｂｌｏｓｓｏｍｉｎｇ方法．成功地重建了平面上贯穿剖分的维数公式．而且利用这种方法，对定义在Ｍｏｒｇａｎ－Ｓｃｏｔ剖分上样条空间的维数取得了一些新的结果．     

n阶矩阵的可交换空间的维数

本文通过研究矩阵的若当相似形矩阵的可交换空间 ,从而得到了矩阵的可交换空间的维数公式     

关于线性子空间与仿射子空间的注记

作为线性方程组的逆问题,本文刻划了线性子空间与仿射子空间分别是某一齐次与非齐次线性方程组的解集,并给出了利用矩阵初等行变换求解相应线性方程组的简便方法;进一步通过仿射子空间引入商空间的概念,建立线性空间的同态基本定理,从而得到维数公式的一个新的证明.     

有限维弱空间的维数定理

向量空间的维数公式，可以推广到比子空间更广的一类弱空间。     

n阶矩阵的可交换空间的维数

本通过研究矩阵的若当相似形矩阵的可交换空间，从而得到了矩阵的可交换空间的维数公式。     

模糊向量空间的商空间

在史和黄重新定义的模糊向量空间的模糊基和模糊维数的基础上,讨论模糊向量空间的模糊线性映射及其性质,定义模糊向量空间(V,μ)的商空间(V/K,μK)并研究了它的性质,证明公式dim(μK)+dim (k(e)ff)=dim(μ)成立,其中k(e)ff是模糊向量空间(V,μ)关于模糊线性映射f的模糊核空间.     

On the Dimensions of Commutative Subalgebras and Subgroups of Nilpotent Algebras and Lie Groups of Class 2

We obtain the functions that bound the dimensions of finite dimensional nilpotent associative or Lie algebras of class 2 over an algebraically closed field in terms of the dimensions of their commutative subalgebras. As a result, we also compute a similar function for complex nilpotent Lie groups of class 2.     

A constructive method to determine the variety of filiform Lie algebras

In this paper we use cohomology of Lie algebras to study the variety of laws associated with filiform Lie algebras of a given dimension. As the main result, we describe a constructive way to find a small set of polynomials which define this variety. It allows to improve previous results related with the cardinal of this set. We have also computed explicitly these polynomials in the case of dimensions 11 and 12.     

Students’ conceptions of mathematics as sensible: Towards the SCOMAS framework

In this article I describe the development of a framework for considering students’ conceptions about the sensible nature of mathematics. I begin by using extant literature on conceptions of mathematics to develop a framework of action-oriented indicators that students’ conceive of mathematics as sensible. I then use classroom data to modify and illustrate the framework. The result is a coding framework, grounded in the literature, which can be used to assess the enacted conceptions of mathematics as sensible of a group of students. This work also provides a conceptual framework, grounded in classroom data, of the dimensions of these conceptions.     

Some Results on the Stability of Non-classical Shock Waves

Part 1 of this paper establishes the infinite-time stability of a class of over-compressive viscous shock waves; the equations studied here are a mathematical analogue of those of magnetohydrodynamics. Part 2 communicates a rather general short-time stability result for undercompressive shock waves in several space dimensions; technically, this is an easy extension of Majda's corresponding result for Laxian shock waves.     

On the local equatorial characterization of zonoids and intersection bodies

In this paper we show that there is no local equatorial characterization of zonoids in odd dimensions. This gives a negative answer to the conjecture posed by W. Weil in 1977 and shows that the local equatorial characterization of zonoids may be given only in even dimensions. In addition we prove a similar result for intersection bodies and show that there is no local characterization of these bodies.     

On a spatial generalization of the Kolosov–Muskhelishvili formulae

The main goal of this paper is to construct a spatial analog to the Kolosov–Muskhelishvili formulae using the framework of the hypercomplex function theory. We prove a generalization of Goursat's representation theorem for solutions of the biharmonic equation in three dimensions. On the basis of this result, we construct explicitly hypercomplex displacement and stress formulae in terms of two monogenic functions. Copyright © 2008 John Wiley & Sons, Ltd.     

On the linear stability of hyperbolic PDEs and viscoelastic flows

The issue addressed in this paper is whether linear stability can be determined from the spectrum. We present a counterexample for a hyperbolic PDE in two dimensions and a positive result for parallel shear flows of a class of viscoelastic fluids.     

线性变换的值域与核的维数关系定理的证法探析

本文首先证明了有限维线性空间上的线性变换是单射当且仅当它是满射这一结论,其次分析了通常高等代数教材中关于线性变换的值域与核的维数关系定理的两种证明方法,并给出了该定理的一种新的证明方法.     

Regular sets for the affine and projective groups over the field of two elements

In this paper we show that collineation groups of affine and projective spaces over the field of two elements GF (2), except in low dimensions, have regular sets. As an application of this result, we prove that, apart from a finite number of exceptions, any collineation group of affine and projective spaces over GF (2), is geometric. In the exceptional dimensions, all primitive groups are examined.Lavoro eseguito nell'ambito dei finanziamenti del M.P.I. Italia (40%).     

Inverse Backscattering Problem for the Acoustic Equation in Even Dimensions

We show that the sound speedc(x) of the acoustic wave equation in any even dimension can be uniquely determined by the backscattering data provided that it is close to a constant. In the three-dimensional case, P. Stefanov and G. Uhlmann (SIAM J. Math. Anal.28,1997, 1191–1204) have proved a similar result. Their method takes advantage of the inversion formula for the Radon transform in odd dimensions being a local operator. This is not true in even dimensions. Moreover, the odd-dimensional Lax and Phillips modified Radon transform fails to work in even dimensions. In this paper, we overcome these difficulties and prove an even-dimensional version of Stefanov and Uhlmann's result.