A Note on Singular Equivalences

Mathematical Notes -     

Some Simple Estimates for the Singular Values of Matrices

Abstract We first provide a simple estimate for ||A~(-1)||_∞ and ||A~(-1)||_1 of a strictly diagonally dominant matrixA. On the Basis of the result, we obtain an estimate for the smallest singular value of A. Secondly, by scalingwith a positive diagonal matrix D, we obtain some simple estimates for the smallest singular value of an H-matrix, which is not necessarily positive definite. Finally, we give some examples to show the effectiveness ofthe new bounds.     

Note on the Characteristic Values and the Three Types of Singular Values of a Complex Matrix

In this paper we prove several inequalities involving the characteristic values, the singular values, the real singular values and the imaginary singular values of a complex matrix.     

A Note on a Singular Integral Equation

A direct method is presented for solving a singular integralequation which is a generalization of one occurring in wave-guidetheory and in the theory of dislocations. The present methodavoids elaborate application of the complex variable methodsnormally associated with such singular integral equations.     

关于一个奇异Dirichlet问题的注记

The Dirichlet problem to a second order differential equation with some singularities is studied. Some existence results are established to the problem which generalize some results recently obtained by D. O‘Regan by eliminating some superfluous constrains to the problem. Also, some new results have been proven which may provide more useful information for the study of the problem.     

简单随机抽样的一个注记

对简单随机抽样两种定义的关系进行了讨论,澄清了教科书中的一些模糊不清之处;通过反例举证了两种定义在某种意义下的不等价性;给出了变概率抽样与不等概率抽样的定义,指出变概率抽样与不等概率抽样也可以是简单随机抽样;本文最后,给出了简单随机抽样的更具一般性的(广义)定义.     

The Thin Film Equation with Non-Zero Contact Angle: A Singular Perturbation Approach

In this paper we consider the thin film equation with prescribed non-zero contact angle condition for a large class of mobility coefficients, in dimension 1. We prove the global in time existence of weak solutions by using a diffuse approximation of the free boundary condition. This approach, which can be physically motivated by the introduction of singular disjoining/conjoining pressure forces had been suggested in particular by Bertsch et al. in [11 Bertsch , M. , Giacomelli , L. , Karali , G. ( 2005 ). Thin-film equations with “partial wetting” energy: Existence of weak solutions . Phys. D 209 : 17 – 27 .[Crossref], [Web of Science ®] , [Google Scholar]].     

关于积域上的粗糙奇异积分算子的一点注记

讨论积域上的奇异积分算子：ＴΩｆ（ｘ,ｙ） ＝ ｐ．ｖ．∫Ｒｎ×ＲｍΩ（ｕ,ｖ）｜ｕ｜ｎ｜ｖ｜ｍ ｆ（ｘ － ｕ,ｙ － ｖ）ｄｕｄｖ的Ｌｐ 有界性,及相应的Ｍａｒｃｉｎｋｉｅｗ ｉｃｚ积分的Ｌ２ 有界性． 其中Ω为类似文［４］中引进的函数类．     

Sensitivity Analysis of Zero Singular Values and Multiple Singular Values

Some results of the author are used to discuss the sensitivity of zero singular values and multiple singular values of a real matrix analytically dependent on several parameters.     

A Note on the p-Laplacian Equation with Singular Coefficients

We consider the solvability of the Dirichlet problem in a unit n-ball for the p-Laplacian equation with singular coefficients which are singular not only as |x| tends to 1 but also as |x| tends to 0. The existence and regularity of positive radial solutions are proved under some conditions related to parameters p, r, λ and q.     

Note on a Singular Integral Equation

A simple direct relationship is.established between solutionsof a singular integral equation encountered in wave-guide theoryand in the theory of dislocations and the solutions of the singularCarleman integral equation.     

A Note on Collars of Simple Closed Geodesics

For compact hyperbolic Riemann surfaces, the collar theorem gives a lower bound on the distance between a simple closed geodesic and all other simple closed geodesics that do not intersect the initial geodesic. Here it is shown that there are two possible configurations, and in each configuration there is a natural collar width associated to a simple closed geodesic. If one extends the natural collar of a simple closed geodesic α by ε >0, then the extended collar contains an infinity of simple closed geodesics that do not intersect α.Mathematics Subject Classiffications (2000). primary: 30F45; secondary: 32G07     

关于粗糙奇异积分算子的一点注记

研究R^n上一类沿多项式曲线的奇异积分算子，在一些相当弱的尺寸条件下建立了这些算子的L^p有界性．     

求矩阵奇异值分解的一种新方法

旨在给出求矩阵奇异值分解的一种新方法.改进和克服了以往方法的缺陷和不足.     

A Note on Two-Weight Inequalities for Maximal Functions and Singular Integrals

We deal with weighted inequalities of the type [formula] where: T is either the Hardy–Littlewood maximal operator or asingular integral operator; G is any measurable subset of Rⁿ; f is any measurable function, vanishing outside G, such thatTf is well-defined; v and w are weights, that is, nonnegativelocally integrable functions on G; p, q(1, ). 1991 Mathematics Subject Classification 42B20, 42B25.     

A Note on Lp Boundedness for Maximal Singular Integrals on Product Domains

§ 1.ＩｎｔｒｏｄｕｃｔｉｏｎａｎｄＳｔａｔｅｍｅｎｔｓｏｆＲｅｓｕｌｔｓ　Ｉｔｉｓｗｅｌｌ ｋｎｏｗｎｔｈａｔｔｈｅｍａｘｉｍａｌｓｉｎｇｕｌａｒｉｎｔｅｇｒａｌｏｎｐｒｏｄｕｃｔｄｏｍａｉｎｓｉｓｖｅｒｙｕｓｅｆｕｌｌｉｎｈａｒｍｏｎｉｃａｎａｌｙｓｉｓ.Ｈｅｒｅｗｅｌｉｓｔｔｗｏｒｅｓｕｌｔｓｒｅｌａｔｅｄｔｏｔｈｉｓｐａｐｅｒ.Ｓｅｅ [1 ] ,[2 ]ａｎｄｔｈｅｒｅｆｅｒｅｎｃｅｓｔｈｅｒｅｉｎ .　Ｆｒｏｍ [1 ] ,ｗｅｋｎｏｗｔｈｅｆｏｌｌｏｗｉｎｇｆａｃｔ.　ＳｕｐｐｏｓｅｔｈａｔＫ(ｘ,ｙ)ｉｓｌ…     

A Note on Commutators with Power Central Values on Lie Ideals

This note proves that, if R is a prime ring of characteristic 2 with d a derivation of R and L a noncentral Lie ideal of R such that [d（u）,u]^n is central, for all u ∈ L, then R must satisfy s4, the standard identity in 4 variables. The case where R is a semiprime ring is also examined by the authors. The results of the note improve Carini and Filippis＇s results.     

Bounds on Singular Values Revealed by QR Factorizations

We introduce a pair of dual concepts: pivoted blocks and reverse pivoted blocks. These blocks are the outcome of a special column pivoting strategy in QR factorization. Our main result is that under such a column pivoting strategy, the QR factorization of a given matrix can give tight estimates of any two a priori-chosen consecutive singular values of that matrix. In particular, a rank-revealing QR factorization is guaranteed when the two chosen consecutive singular values straddle a gap in the singular value spectrum that gives rise to the rank degeneracy of the given matrix. The pivoting strategy, called cyclic pivoting, can be viewed as a generalization of Golub's column pivoting and Stewart's reverse column pivoting. Numerical experiments confirm the tight estimates that our theory asserts.     

随机变量数学期望的一个注记

介绍一种计算随机变量数学期望的方法,利用这种方法容易得到数学期望的相关性质,很多概率与矩的不等式证明也因之变得更为简洁.