Pinchings and Norms of Scaled Triangular Matrices

Suppose U is an upper-triangular matrix, and D a nonsingular diagonal matrix whose diagonal entries appear in nondescending order of magnitude down the diagonal. It is proved that $$|D^{-1}UD|ge|U|$$ for any matrix norm that is reduced by a pinching. In addition to known examples -weakly unitarily invariant norms - we show that any matrix norm defined by $$| A |^{underline{underline {{rm def}}} } mathop {max }limits_{x ne 0,y ne 0} {{{mathop{rm Re}nolimits} (x^*Ay)} over {phi (x)psi (y)}},$$ where θ (.) and y (.) are two absolute vector norms, has this property. This includes l p operator norms as a special case.     

Rank Reducing Matrix Norms

We consider approximation numbers for some norms on matrices, and look at the question when a closest rank h p approximant can be chosen to reduce the rank of a matrix by p . If the latter is always possible, we call the norm rank p reducing. It is easily seen that any unitarily invariant norm is rank p reducing. We show that any absolute norm on $\shadC^{n \times m}$ is rank n m 1 reducing and that the numerical radius norm on $ \shadC^{n\times n}$ is rank n m 1 reducing as well. Non-examples and computations of approximation numbers are also presented.     

L-矩阵与三角模

利用完备的分配格L上三角模定义L上的矩阵运算,给出这些运算的一些基本性质,并且详细讨论L上的几类方阵.     

一类二元函数连续性的等价刻画及在三角模上的应用

关于二元函数的连续,经典数学分析中有熟知的结果,即"如果二元函数连续,则必关于每个单变量连续。反之,则未必"。本文证明对于单调且对称的二元函数而言,其二元连续等价于单变量连续,并重新定义了三角模的连续。     

三角模糊数互补判断矩阵的一种排序方法

给出三角模糊数互补判断矩阵的概念及三角模糊数相互比较的可能度公式 ,提出一种基于可能度的三角模糊数互补判断矩阵排序方法 ,通过算例说明该方法的可行性和有效性。     

Modular Automorphisms of Upper Triangular Matrices over a Commutative Ring Preserving Rank One

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Research problem: on the norms of infinite Cauchy-Toeplitz-plus-Cauchy-Hankel matrices

We give a conjecture and research problem related to ℓ_p operator and spectral norms of the matrix T_n + H_n.     

基于专家重要性的语言诱导有序加权平均算子的多粒度语言组合判断矩阵的相容性和一致性

定义了多粒度语言判断矩阵的基于专家重要性的语言诱导有序加权平均(I-LIOWA)算子的概念,利用I-LIOWA算子集结基于不同粒度语言判断矩阵而得到组合语言判断矩阵,并且研究了组合语言判断矩阵、其导出矩阵和特征矩阵的之间相容性和一致性的一些性质,为群决策中使用语言偏好信息提供了理论依据。     

Inequalities for hadamard product and unitarily invariant norms of matrices

The paper contains some general theorems for Hadamard product of matrices which in particular include Fiedler's Theorem and a better bound for an inequality on product of eigenvalues of certain matrices due to Ando. Lieb's concavity Theorem has been proved using operator means. Some inequalities for unitarily invariant norms have also been proved.     

Critical Points and Error Rank in Best H 2 Matrix Rational Approximation of Fixed McMillan Degree

This paper deals with best rational approximation of prescribed McMillan degree to matrix-valued functions in the real Hardy space of the complement of the unit disk endowed with the Frobenius L ₂ -norm. We describe the topological structure of the set of approximants in terms of inner-unstable factorizations. This allows us to establish a two-sided tangential interpolation equation for the critical points of the criterion, and to prove that the rank of the error F-H is at most k-n when F is rational of degree k , and H is critical of degree n . In the particular case where k=n , it follows that H=F is the unique critical point, and this entails a local uniqueness result when approximating near-rational functions. January 23, 1996. Date revised: September 16, 1996.