Almost constrained subspaces of Banach spaces

In this paper, we obtain some sufficient conditions for an almost constrained subspace to be constrained (in fact, by a unique norm 1 projection), which improves significantly upon all existing conditions of similar type with significantly simpler proofs.

     

Further criteria for positive Harris recurrence of Markov chains

We provide several necessary and sufficient conditions for a Markov chain on a general state space to be positive Harris recurrent. The conditions only concern asymptotic properties of the expected occupation measures.

     

Planar embeddings with a globally attracting fixed point

We consider sufficient conditions which guarantee that an embedding from the plane R²${\mathbb{R}}^2$ into itself has a unique fixed point. We subsequently study sufficient conditions under which there appears a globally attracting fixed point for such an embedding.     

Burghelea-Friedlander-Kappeler's gluing formula for the zeta-determinant and its applications to the adiabatic decompositions of the zeta-determinant and the analytic torsion

The gluing formula of the zeta-determinant of a Laplacian given by Burghelea, Friedlander and Kappeler contains an unknown constant. In this paper we compute this constant to complete the formula under an assumption that the product structure is given near the boundary. As applications of this result, we prove the adiabatic decomposition theorems of the zeta-determinant of a Laplacian with respect to the Dirichlet and Neumann boundary conditions and of the analytic torsion with respect to the absolute and relative boundary conditions.

     

H1(Rn)的极大函数特征

当ψ(x),x∈R^n满足较弱的大小和光滑性条件时，本文证明了由它定义的极大函刻画了Hardy空间H^1(R^n）。     

The convexity lattice of a poset

The authors investigate the lattice Co(P) of convex subsets of a general partially ordered set P. In particular, they determine the conditions under which Co(P) and Co(Q) are isomorphic; and give necessary and sufficient conditions on a lattice L so that L is isomorphic to Co(P) for some P.     

Recognizing unstable equidimensional maps, and the number of stable projections of algebraic hypersurfaces

We study the recognition of -classes of multi-germs in families of corank-1 maps from n-space into n-space. From these recognition conditions we deduce certain geometric properties of bifurcation sets of such families of maps. As applications we give a formula for the number of -codimension-1 classes of corank-1 multi-germs from ℂ ⁿ to ℂ ⁿ and an upper bound for the number of stable projections of algebraic hypersurfaces in ℝ ^{n +1} into hyperplanes. Received: 23 July 1998     

Critical degenerate inequalities¶on the Heisenberg group

Necessary and sufficient conditions are given that answer the following questions: When does an integer valued (real valued) g-additive function have a limit distribution modulo an integer (modulo 1)? When are the limit distributions continuous or uniform? When is a complex valued g-additive function almost periodic? Received: 6 February 2001 / Revised version: 30 May 2001     

Lazarsfeld-Mukai reflexive sheaves and their stability

Consider an ample and globally generated line bundle L on a smooth projective variety X of dimension N≥2 over ?. Let D be a smooth divisor in the complete linear system of L. We construct reflexive sheaves on X by an elementary transformation of a trivial bundle on X along certain globally generated torsion-free sheaves on D. The dual reflexive sheaves are called the Lazarsfeld-Mukai reflexive sheaves. We prove the μ_L-(semi)stability of such reflexive sheaves under certain conditions.     

Approximation by translates of refinable functions

Summary. The functions are refinable if they are combinations of the rescaled and translated functions . This is very common in scientific computing on a regular mesh. The space of approximating functions with meshwidth is a subspace of with meshwidth . These refinable spaces have refinable basis functions. The accuracy of the computations depends on , the order of approximation, which is determined by the degree of polynomials that lie in . Most refinable functions (such as scaling functions in the theory of wavelets) have no simple formulas. The functions are known only through the coefficients in the refinement equation – scalars in the traditional case, matrices for multiwavelets. The scalar "sum rules" that determine are well known. We find the conditions on the matrices that yield approximation of order from . These are equivalent to the Strang–Fix conditions on the Fourier transforms , but for refinable functions they can be explicitly verified from the . Received August 31, 1994 / Revised version received May 2, 1995     

A new cement to glue non-conforming grids with Robin interface conditions: The finite volume case

Summary Robin interface conditions in domain decomposition methods enable the use of non overlapping subdomains and a speed up in the convergence. Non conforming grids make the grid generation much easier and faster since it is then a parallel task. The goal of this paper is to propose and analyze a new discretization scheme which allows to combine the use of Robin interface conditions with non-matching grids. We consider both a symmetric definite positive operator and the convection-diffusion equation discretized by finite volume schemes. Numerical results are shown. Received December 22, 1999 / Revised version received December 21, 2000 / Published online December 18, 2001 Correspondence to: F. Nataf     

Generalization of a problem of Lehmer

Given a prime number p, Lehmer raised the problem of investigating the number of integers for which a and are of opposite parity, where is such that . We replace the pair by a point lying on a more general irreducible curve defined mod p and instead of the parity conditions on the coordinates more general congruence conditions are considered. An asymptotic result is then obtained for the number of such points. Received: 12 July 2000 / Revised version: 7 November 2000     

样本评价DEA模型的灵敏度分析

利用样本评价DEA模型的有效性理论,对决策单元的有效性进行灵敏度分析,给出了当移动因子d保持不变时,样本单元和决策单元的输入或输出变化后,决策单元的有效性保持不变的充分条件和必要条件,此外还给出了使决策单元的有效性保持不变的移动因子d的精确变化范围,最后通过实例表明了该灵敏度分析方法的可行性.     

On the equations of thermally radiative magnetohydrodynamics

An initial–boundary value problem is considered for the viscous compressible thermally radiative magnetohydrodynamic (MHD) flows coupled to self-gravitation describing the dynamics of gaseous stars in a bounded domain of R³${\mathbb{R}}^3$. The conservative boundary conditions are prescribed. Compared to Ducomet–Feireisl [13] (also see, for instance, Feireisl [18], Feireisl–Novotný [20]), a rather more general constitutive relationship is given in this paper. The analysis allows for the initial density with vacuum. Every transport coefficient admits a certain temperature scaling. The global existence of a variational (weak) solution with any finite energy and finite entropy data is established through a three-level approximation and methods of weak convergence.     

Baire spaces and hyperspace topologies

Sufficient conditions for abstract (proximal) hit-and-miss hyperspace topologies and the Wijsman hyperspace topology, respectively, are given to be Baire spaces, thus extending results of McCoy, Beer, and Costantini. Further the quasi-regularity of (proximal) hit-and-miss topologies is investigated.

     

LIPSCHITZ SEMISTABILITY OF GENERAL CONTROL SYSTEMS IN TERMS OF TWO MEASURES

1 IntroductionLipschitz semistability of dynamical systems in terms of two measures andLipschitz semistability of general control systems have already been,t.di.d[llt12].In this papers semistability considerations will be extended to a variety of nonlinear systems utilizing the same versatile tools, namely, Liapunov--like functions. The notions of (ho, h)-Lipschitz (weak) semistability of general controlsystems are introduced, and the necessary and sufficient conditions are given.2 Prelimina…     

On projected Runge-Kutta methods for differential-algebraic equations

Ascher and Petzold recently introducedprojected Runge-Kutta methods for the numerical solution of semi-explicit differential-algebraic systems of index 2. Here it is shown that such a method can be regarded as the limiting case of a standard application of a Runge-Kutta method with a very small implicit Euler step added to it. This interpretation allows a direct derivation of the order conditions and of superconvergence results for the projected methods from known results for standard Runge-Kutta methods for index-2 differential-algebraic systems, and an extension to linearly implicit differential-algebraic systems.     

Approximation de quelques problèmes de type Stokes par une méthode d'éléments finis mixtes

Résumé Nous présentons dans cet article une méthode d'éléments finis mixtes qui permet la résolution des équations de Stokes avec des conditions aux limites de type Fourier ou Neumann. Pour cette méthode nous démontrons que les estimations de l'erreur d'approximation sont optimales; en vitesse et en pression. Ces résultats de convergences généralisent à ce type non standard de conditions aux limites les travaux de Glowinski-Pironneau [9, 10] pour le probleme de Stokes avec des conditions aux limites de Dirichlet.

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Mixed-finite element approximation of stokes type problems

Summary We present in this paper a mixed-finite element approximation of Stokes equations with boundary conditions of Fourier's or Neumann's type. For this approximation we prove that the error estimates for the velocity-vector and for the pressure are optimal. These results of convergence generalize to this kind of boundary conditions the Glowinski-Pironneau's approximation of Stokes problem with Dirichlet's boundary conditions [9, 10].

     

Minimal decompositions and iterative methods

Summary. The aim of this paper is to prove some Babuška–Brezzi type conditions which are involved in the mortar spectral element discretization of the Stokes problem, for several cases of nonconforming domain decompositions. ID=" <E5>Dedicated to Olof B. Widlund on the occasion of his 60th birthday</E5>