关于正则态射的广义Moore-Penrose逆

通过态射的正则性,讨论加法范畴中态射的广义Moore-Penrose逆.给出了正则态射的广义Moore-Penrose逆存在的几个充要条件以及广义Moore-Penrose逆的表达式.     

具有广义分解态射的加权Moore-Penrose逆

研究范畴中态射的加权Moore-Penrose逆,利用态射广义分解的性质给出了态射加权Moore-Penrose逆存在的一些充要条件,导出了态射的加权Moore-Penrose逆的表达式,推广了态射Moore-Penrose逆的相应结果.     

具有满单泛分解态射的广义逆

态射的Moore-Penrose逆是矩阵的Moore-Penrose逆在有对合＊的范畴中的推广．本文着重给出具有满单泛分解态射f的（1，3．4）-逆和Moore-Penrose存在的充要条件，同时也推广了具有泛分解广义逆的相应结果．     

关于具有泛分解态射的广义Moore-

本文讨论预加法范畴中态射的广义Moore-Perurose逆．给出了具有泛分解态射的广义Moore-Penrose逆存在的几个充要条件,并把结果应用到环上的矩阵中．     

具有广义分解态射的广义(i,…,j)逆

本文研究范畴中态射的广义(i，…，j)逆，利用态射广义分解的性质给出了态射广义(i，…，j)逆存在的一些充要条件，导出了态射的广义Moore-Penrose逆的表达式，推广了态射(i，…，j)逆的相应结果．     

具有核的态射广义Moore-Penrose逆

本文研究了具有核的态射广义Moore-Penrose逆.利用加边态射的可逆性,获得了态射广义Moore-Penrose逆存在的一些新的充要条件及相关表达式,推广了态射Moore-Penrose逆的相应结论.     

态射的加权Moore—Penrose逆

本给出了一般态射的加权Moore-Penrose逆存在的一些新的充要条件及态射乘积的加权Moore-Penrose逆的反序律成立的充要条件，也给出了具有泛分解的态射和有核（上核）的态射的加权Moore-Penrose逆存在的一些新的充要条件及相关表达式。     

关于具有泛分解态射的加权Moore-Penrose逆

给出了预加法范畴中具有泛分解态射的加权Moore-Penrose逆存在的充要条件及其表达式,推广了具有泛分解的态射的Moore-Penrose逆的相应结果.     

具有泛分解的态射的广义Moore—Penrose逆

本文给出预加范畴中具泛分解和广义分解的态射的广义Moore-Penrose逆存在的条件及其表达式,推广了具泛分解态射Moore-Penrose逆的有关结果。     

关于态射的加权Moore-Penrose逆

研究了范畴中态射 f关于态射β和γ的加权 Moore-Penrose逆 fβ,γ+,分别给出了一般态射、有满单分解态射与有核 (上核 )的 fβ,γ+存在的充要条件及其相应的表达式 ,推广了 f关于对称态射β和γ的加权Moore-Penrose逆的相应结果 .     

Reducing subspaces of compressed analytic Toeplitz operators on the Hardy space

In this paper we discuss necessary conditions and sufficient conditions for the compression of an analytic Toeplitz operator onto a shift coinvariant subspace to have nontrivial reducing subspaces. We give necessary and sufficient conditions for the kernel of a Toeplitz operator whose symbol is the quotient of two inner functions to be nontrivial and obtain examples of reducing subspaces from these kernels. Motivated by this result we give necessary conditions and sufficient conditions for the kernel of a Toeplitz operator whose symbol is the quotient of two inner functions to be nontrivial in terms of the supports of the two inner functions. By studying the commutant of a compression, we are able to give a necessary condition for the existence of reducing subspaces on certain shift coinvariant subspaces.     

Lifting Property of Direct Sums of Hollow Modules

We give necessary and sufficient conditions for a module M with a decomposition that complements maximal direct summands to be a lifting module. We apply our results to get a necessary and sufficient condition for a direct sum of modules to be a quasi-discrete (discrete) module. We also give some sufficient conditions for a lifting module to be a direct sum of indecomposables.     

The structure of transitive ordered permutation groups

We give some necessary and sufficient conditions for transitive l-permutation groups to be 2-transitive. We also discuss primitive components and give necessary and sufficient conditions for transitive l-permutation groups to be normal-valued.     

Total positivity and the existence of piecewise exponential B-splines

We give necessary and sufficient conditions for the total positivity of certain connection matrices arising in piecewise exponential spline spaces. These total positivity conditions are sufficient for existence of B-splines in such spaces, but they are far from being necessary. We give a necessary and sufficient condition for existence of B-splines in the case of piecewise exponential spline spaces with only two differential operators, which eventually leads to a necessary condition for any piecewise exponential spline spaces. Dedicated to Professor Charles A. Micchelli for his 60th birthday Mathematics subject classifications (2000) 65D17, 65D07, 41A15, 41A50.     

条件期望作为初等算子在冯-代数上的描述

定义并研究了冯-代数.条件期望基于冯-代数的描述,即作为初等算子的良好性质,会较之一般代数简洁许多.这是因为冯-代数包含一些特殊的子代数.给出了此类代数上置信的初等条件期望的描述及其最小存在的充要条件.并且定义了指标冯-有限条件期望.作为以上结果的推论,得出了条件期望指标有限的充分必要条件和一个重要不等式.     

Slant and pseudo-slant submanifolds in LCS-manifolds

We show new results on when a pseudo-slant submanifold is a LCS-manifold. Necessary and sufficient conditions for a submanifold to be pseudo-slant are given. We obtain necessary and sufficient conditions for the integrability of distributions which are involved in the definition of the pseudo-slant submanifold. We characterize the pseudoslant product and give necessary and sufficient conditions for a pseudo-slant submanifold to be the pseudo-slant product. Also we give an example of a slant submanifold in an LCS-manifold to illustrate the subject.     

Arc-Disjoint and Edge-Disjoint Hamilton Cycles in Circulants with Two Jumps

In this paper we give new necessary and sufficient conditions for a directed circulant with vertices of outdegree two to have a pair of arc-disjoint Hamilton cycles. These conditions explicitly identify a pair of arc-disjoint Hamilton cycles if such cycles exist. In addition, we give necessary and sufficient conditions for an undirected circulant with vertices of degree four to have a specific pair of edge-disjoint Hamilton cycles.     

Cycles and paths in bipartite tournaments with spanning configurations

We give necessary and sufficient conditions in terms of connectivity and factors for the existence of hamiltonian cycles and hamiltonian paths and also give sufficient conditions in terms of connectivity for the existence of cycles through any two vertices in bipartite tournaments.     

The Borel property for simple Riesz means

We give a necessary and sufficient condition for the Borel property for weighted means. If the sequence of weights is increasing, then Hill's condition is necessary and sufficient.Dedicated to Professor E. Hlawka on the occasion of his seventieth birthday     

Auslander algebras Of finite representation type

In this paper we give necessary and sufficient conditions for Auslander-Reiten quivers to be of finite representation type. If an algebra is standard this gives necessary and sufficient conditions for Auslander algebras to be of finite representation type.