凸锥的一个广义内部性质

在集合的拟内部和相对代数内部非空的条件下给出了凸锥的一个广义内部性质,证明了凸锥的拟内部和相对代数内部的一致性,进而建立了基于凸锥的拟内部和相对代数内部的非凸分离定理.此外,也给出了一些具体例子对主要结果进行了解释.     

凸像象形照相的Bloch常数

1.通过一个平面凸区域的一个边界点而把这个凸区域包含在内部的圆周叫做这凸区域在这个边界点的支持圆周.假如把直线看做半径是无限大的圆周的话,那末支持直线正是支持圆周的特别情形,因此一个平面凸区域一定在它的每个边界点都有支持圆周。现在我们要来证明下面这个     

C~*-代数拟对角扩张的α-比较性（英文）

设A为一个含单位元的C~*-代数,且有拟对角扩张0→I→A→πA/I→0.则A具有α-比较性,当且仅当I与A/I都具有α-比较性.     

L-fuzzy层拟一致结构理论

在L-拓扑空间中提出α-远域族和α-拟一致结构的概念,讨论它的一些基本性质。在此基础上证明了每一个α-拟一致结构都可以诱导出一个α-层拓扑,每个α-层拓扑空间都可以α-拟一致化。由此,进一步分析α-拟一致连续与层连续之间的关系。     

极大代数上有限生成模的凸性

研究极大代数上有限生成模的凸性.基于极大代数上有限生成模的几何形态,运用代数与几何方法,分析空间维数n≤3和生成向量数m≥1的有限生成模的凸性.证明n=1,2的有限生成模是凸集.对于n=3,给出m=2的有限生成模为凸集的一个充分必要条件,以及m≥3的有限生成模为凸集的一个充分条件.此外,对于极大代数上有限生成模的几何形态,发现n=3,m≥3的形态有三种情形.     

无条件C的广义αη-单调性的判别标准

用α和η关于第一分量是仿射的且是斜对称的条件代替条件C,得到如下结论:(1)如果一个函数的梯度是(严格)αη-伪单调的,则该函数是(严格)伪αη-不变凸的;(2)如果一个函数的梯度是拟αη-单调的,则该函数是拟αη-不变凸的.     

强拟α-预不变凸函数

研究了一类重要的广凸函数——强拟α-预不变凸函数,讨论了它与拟α-预不变凸函数、严格拟α-预不变凸函数及半严格拟α-预不变凸函数之间的关系,并在中间点的强拟α-预不变凸性下得到了它的三个重要的性质定理,同时给出了强拟α-预不变凸函数在数学规划中的两个重要应用,这些结果在一定程度上完善了对强拟α-预不变凸函数的研究.     

广义度量S-KKM映射的性质及其对变分不等式的应用

引入了超S-γ-广义拟凸（凹）函数,建立了广义度量S-KKM映射与超S-γ-广义拟凸（凹）函数的关系.作为应用,获得了超凸度量空间中的新的KyFan极大极小不等式和鞍点定理.     

G -凸空间中的广义对策和广义矢量拟平衡问题组

该文在广义G -凸空间中引入并研究了一类新的广义矢量拟平衡问题组(SGVQEP).利用作者的一族集值映象的极大元存在定理,证明了广义对策的一个新的平衡存在定理.作为应用,在非紧乘积G -凸空间中证明了SGVQEP解的一些新的存在定理.     

强拟凸域上Toeplitz算子的Fredholm指标公式及相关问题

在具有光滑边界的强拟凸域Ω上（n＞1）．用方程可解性的技巧，证明了多复变Hardy（Bergman）空间上符号属于H∞＋C的FredholmToeplitz算子的指标为零．同时，结合B－D－F定理研究了Bergman空间上由全体Toeplitz算子生成的C-代数．在Bergman空间上，回答了M.Englis的一个问题。     

Diffraction of creeping waves from a point of curvature jump on the boundary of a domain (The point of transition of the convex boundary into the concave boundary)

The problem of diffraction of a creeping wave propagating in a domain near the convex part of the boundary and overrunning a point where the convex boundary transforms to the concave one is studied. The tangent to the boundary is continuous at this point, but the derivative of the tangent has the jump. The Green's function to the right of the point of jump of curvature is a superposition of whispering gallery waves. The Dirichlet, Neumann, and impedance boundary conditions are considered. The formulas for the boundary current and for the diffraction coefficients related to the problem are obtained. Bibliography: 3 titles. Translated fromZapiski Nauchnykh Seminarov POMI, Vol. 250, 1998, pp. 288–299. Translated by N. Ya. Kirpichnikova     

Stationary Boltzmann's equation with Maxwell's boundary conditions in a bounded domain

The paper deals with the stationary Boltzmann equation in a bounded convex domain Ω. The boundary ?Ω is assumed to be a piecewise algebraic variety of the C²-class that fulfils Liapunov's conditions. On the boundary we impose the so-called Maxwell boundary conditions, that is a convex combination of specular and diffusive reflections. The non-linear Boltzmann equation is considered with additional volume and boundary source terms and it has been proved that for sufficiently small sources the problem possesses a unique solution in a properly chosen subspace of C(Ω × ?³). The proof is a refined version of the proof delivered by Guiraud for purely diffusive reflection.     

Projected Schur complement method for solving non‐symmetric systems arising from a smooth fictitious domain approach

This paper deals with a fast method for solving large‐scale algebraic saddle‐point systems arising from fictitious domain formulations of elliptic boundary value problems. A new variant of the fictitious domain approach is analyzed. Boundary conditions are enforced by control variables introduced on an auxiliary boundary located outside the original domain. This approach has a significantly higher convergence rate; however, the algebraic systems resulting from finite element discretizations are typically non‐symmetric. The presented method is based on the Schur complement reduction. If the stiffness matrix is singular, the reduced system can be formulated again as another saddle‐point problem. Its modification by orthogonal projectors leads to an equation that can be efficiently solved using a projected Krylov subspace method for non‐symmetric operators. For this purpose, the projected variant of the BiCGSTAB algorithm is derived from the non‐projected one. The behavior of the method is illustrated by examples, in which the BiCGSTAB iterations are accelerated by a multigrid strategy. Copyright © 2007 John Wiley & Sons, Ltd.     

Invariant subspaces for operators whose spectra are Carathéodory regions

In this paper it is shown that if an operator T satisfies ‖p(T)‖?‖p_‖σ(T) for every polynomial p and the polynomially convex hull of σ(T) is a Carathéodory region whose accessible boundary points lie in rectifiable Jordan arcs on its boundary, then T has a nontrivial invariant subspace. As a corollary, it is also shown that if T is a hyponormal operator and the outer boundary of σ(T) has at most finitely many prime ends corresponding to singular points on ∂D and has a tangent at almost every point on each Jordan arc, then T has a nontrivial invariant subspace.     

Separable Determination of the Fixed Point Property of Convex Sets in Banach Spaces

In this paper, we first show that for every mapping $f$ from a metric space $Ω$ to itself which is continuous off a countable subset of $Ω,$ there exists a nonempty closed separable subspace $S ⊂ Ω$ so that $f|_S$ is again a self mapping on $S.$ Therefore, both the fixed point property and the weak fixed point property of a nonempty closed convex set in a Banach space are separably determined. We then prove that every separable subspace of $c_0(\Gamma)$ (for any set $\Gamma$) is again lying in $c_0.$ Making use of these results, we finally presents a simple proof of the famous result: Every non-expansive self-mapping defined on a nonempty weakly compact convex set of $c_0(\Gamma)$ has a fixed point.     

Transverse curves and chain curvature in the Heisenberg group

A chain is the intersection of a complex totally geodesic subspace in complex hyperbolic 2-space with the boundary. The boundary admits a canonical contact structure, and chains are distiguished curves transverse to this structure. The space of chains is analyzed both as a quotient of the contact bundle, and as a subset of ℂP². The space of chains admits a canonical, indefinite Hermitian metric, and curves in the space of chains with null tangent vectors are shown to correspond to a path of chains tangent to a curve in the boundary transverse to the contact structure. A family of local differential chain curvature operators are introduced which exactly characterize when a transverse curve is a chain. In particular, operators that are invariant under the stabilizer of a point in the interior of complex hyperbolic space, or a point on the boundary, are developed in detail. Finally, these chain curvature operators are used to prove a generalization of Louiville's theorem: a sufficiently smooth mapping from the boundary of complex hyperbolic 2-space to itself which preserves chains must be the restriction of a global automorphism.     

The edge wave in the problem of diffraction on a boundary with jump of curvature

The problem of the diffraction of creeping waves on a point of transition of the convex boundary to the straight boundary of a domain is investigated. It is assumed that at the point of jump of curvature, the tangent to the boundary is continuous and its derivative has a jump. An expression for the edge wave is obtained and investigated. Bibliography: 4 titles. Translated fromZapiski Nauchnykh Seminarov POMI, Vol. 250, 1998, pp. 274–287. Translated by N. Ya. Kirpichnikova.     

Domains of Holomorphy with Edges and Lower Dimensional Boundary Singularities

It is shown that a domain in C ^N with piecewise smooth boundary (and also of some more general shape) is a domain of holomorphy, provided the Levi form at every regular point is positively semidefinite and the tangent cone is convex at every point outside a boundary subset of zero Hausdorff (2N-2)-dimensional measure.     

On the best parametrization

The numerical solution to a system of nonlinear algebraic or transcendental equations with several parameters is examined in the framework of the parametric continuation method. Necessary and sufficient conditions are proved for choosing the best parameters, which provide the best condition number for the system of linear continuation equations. Such parameters have to be sought in the subspace tangent to the solution space of the system of nonlinear equations. This subspace is obtained if the original system of nonlinear equations is solved at the various parameter values from a given set. The parametric approximation of curves and surfaces is considered.     

基于代数等价变换下的凸二次规划不可行内点算法

基于代数等价变换和在KMM算法的框架基础上,在原始-对偶内点方法的牛顿方程里嵌入一种自调节功能.从而对凸二次规划提出了一种新的迭代方向的不可行内点算法,并证明了算法的全局收敛性.