The ANR-property of hyperspaces with the Attouch-Wets topology

We characterize metric spaces whose hyperspaces of non-empty closed, bounded, compact or finite subsets, endowed with the Attouch-Wets topology, are absolute (neighborhood) retracts.      

Wijsman and Hit-and-Miss Topologies of Quasi-Metric Spaces

The relationship between the Wijsman topology and (proximal) hit-and-miss topologies is studied in the realm of quasi-metric spaces. We establish the equivalence between these hypertopologies in terms of Urysohn families of sets. Our results generalize well-known theorems and provide easier proofs. In particular, we prove that for a quasi-pseudo-metrizable space (X,T) the Vietoris topology on the set P ₀(X) of all nonempty subsets of X is the supremum of all Wijsman topologies associated with quasi-pseudo-metrics compatible with T. We also show that for a quasi-pseudo-metric space (X,d) the Hausdorff extended quasi-pseudo-metric is compatible with the Wijsman topology on P ₀(X) if and only if d ^–1 is hereditarily precompact.     

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.

     

Gap, Excess and Bornological Convergence

Let be the nonempty subsets of a metric space 〈X, d〉. Some classical convergences in - such as convergence in Hausdorff distance, Attouch-Wets convergence and Wijsman convergence - have been shown to be compatible with the weak topology on induced by all gap and excess functionals with fixed left argument ranging in some bornology. Here we consider an arbitrary ideal of subsets of X and compare the gap and excess topology so generated with the corresponding convergence defined in terms of truncations by elements of the ideal. Dedicated to the memory of Flora Daniel.     

Proximal Hypertopologies Revisited

It is the aim of this paper to prove that for an arbitrary metric space (X,d) and a set of nonempty closed subsets of X which contains all singletons and which is closed under enlargements, we can construct a canonical approach distance on the hyperspace CL(X), having the -proximal topology (resp. the Hausdorff metric) as its topological (resp. p-metric) coreflection. We investigate some properties like, e.g., compactness and completeness of the introduced approach structures. In this way we obtain results which generalize their classical counterparts for proximal hit-and-miss hypertopologies. We also give a characterization of the completion of the introduced approach spaces.     

Hausdorff dimension and doubling measures on metric spaces

Volberg and Konyagin have proved that a compact metric space carries a nontrivial doubling measure if and only if it has finite uniform metric dimension. Their construction of doubling measures requires infinitely many adjustments. We give a simpler and more direct construction, and also prove that for any , the doubling measure may be chosen to have full measure on a set of Hausdorff dimension at most .

     

Uniform convergence on spaces of multifunctions

We study spaces of multifunctions with closed values, multifunctions with closed graphs, USCO multifunctions, minimal USCO multifunctions and the space of densely continuous forms as metric spaces, equipped with the topology of uniform convergence. We give conditions under which these metric spaces are complete.      

Hypertopologies on function spaces

The aim of this paper is to continue Naimpally’s seminal papers [16], [17], [18], i.e. we investigate topological properties of spaces which force the coincidence of convergences of functions associated with different hyperspace topologies. For example a metric spaceX is locally compact iff the topological convergence and the convergence induced by the Fell topology coincide onC(X,IR). Moreover, the proximal topology on the space of functions, not necessarily continuous, is studied in great detail.     

Hyperbolic multi-topology and the basic principle in quantum mechanics

In this paper, applying the direction strangeness of the hyperbolic space-time, we introduce the double metric space and the multi-topological structure, and in the wave-particle topology, we give one kind of imaginary metric representation for light-quantum hypothesis, uncertainty principle, energy level transition and interference conditions, etc. in quantum mechanics.     

分数次积分交换子在非齐Morrey空间上的紧性

The aim of this paper is to establish the necessary and sufficient conditions for the compactness of fractional integral commutator[b,I_γ]which is generated by fractional integral I_γand function b∈Lip_β(μ)on Morrey space over non-homogeneous metric measure space,which satisfies the geometrically doubling and upper doubling conditions in the sense of Hytonen.Under assumption that the dominating functionλsatisfies weak reverse doubling condition,the author proves that the commutator[b,I_γ]is compact from Morrey space M_q^p(μ)into Morrey space M_t^s(μ)if and only if b∈Lip_β(μ).     

Banach空间闭子集上微分方程解的整体存在唯一性定理

本文利用比较方法和Kuratowski非紧致测度研究Banach空间闭子集上微分方程解的整体存在唯一性,得出了一个一般性判别准则.作为特例,本文的结果包含了文[4]中的主要定理.     

有界对称域上的VMOp与VO空间的乘子

该文利用Berezin变换,自同构群及Bergman再生核理论,对有界对称域上的VMOp 与VO空间的点态乘子进行了刻划．     

第四类Caftan-Hartogs域上Bergman度量与Einstein-Kahler度量等价

In this paper,we discuss the invariaut complete metric on the Cartan-Hartogs domain of the fourth type.Firstly,we find a new invariant complete metric,and prove the equivalence between Bergman metric and the new metric;Secondly,the Ricci curvature of the new metric has the super bound and lower bound;Thirdly,we prove that the holomorphic sectional curvature of the new metric has the negative supper bound;Finally,we obtain the equivalence between Bergman metric and Einstein-Kahler metric on the Cartan-Hartogs domain of the fourth type.     

Properties of the metric projection on weakly vial-convex sets and parametrization of set-valued mappings with weakly convex images

We continue studying the class of weakly convex sets (in the sense of Vial). For points in a sufficiently small neighborhood of a closed weakly convex subset in Hubert space, we prove that the metric projection on this set exists and is unique. In other words, we show that the closed weakly convex sets have a Chebyshev layer. We prove that the metric projection of a point on a weakly convex set satisfies the Lipschitz condition with respect to a point and the Hölder condition with exponent 1/2 with respect to a set. We develop a method for constructing a continuous parametrization of a set-valued mapping with weakly convex images. We obtain an explicit estimate for the modulus of continuity of the parametrizing function.     

Normal almost contact metric structures of hyperbolic type of the first kind on hypersurfaces of a space of constant holomorphic curvature of hyperbolic type

We consider normal integrable Sasakian almost contact metric structures of hyperbolic type of the first kind on hypersurfaces of a space of constant holomorphic curvature of hyperbolic type, in particular, on hypersurfaces of a flat A-space of hyperbolic type.__________Translated from Lietuvos Matematikos Rinkinys, Vol. 45, No. 1, pp. 22–32, January–March, 2005.Translated by V. Mackeviius     

Control and Stabilization of the Korteweg-de Vries Equation on a Periodic Domain

In [38 Russell , D.L. , Zhang , B.-Y. ( 1996 ). Exact controllability and stabilizability of the Korteweg-de Vries equation . Trans. Amer. Math. Soc. 348 : 3643 – 3672 . [Google Scholar]], Russell and Zhang showed that the Korteweg-de Vries equation posed on a periodic domain  with an internal control is locally exactly controllable and locally exponentially stabilizable when the control acts on an arbitrary nonempty subdomain of . In this paper, we show that the system is in fact globally exactly controllable and globally exponentially stabilizable. The global exponential stabilizability is established with the aid of certain properties of propagation of compactness and regularity in Bourgain spaces for the solutions of the associated linear system. With Slemrod's feedback law, the resulting closed-loop system is shown to be locally exponentially stable with an arbitrarily large decay rate. A time-varying feedback law is further designed to ensure a global exponential stability with an arbitrarily large decay rate.     

Banach空间中线性流形上的度量投影的表达式

借助于正规对偶映射,建立了一般Banach空间中线性流形上的(集值)度量投影存在的 充要条件,同时给出了度量投影的表达式和点到线性流形上的距离公式.这些本质地推广和改进了 王玉文和于金凤在空间自反、严格凸和光滑强假定下的相应结果.     

Existence and Numerical Solutions of Nonlinear Quadratic Integral Equations Defined on Unbounded Intervals

The first goal of this article is to discuss the existence of solutions of nonlinear quadratic integral equations. These equations are considered in the Banach space L ^p (?₊). The arguments used in the existence proofs are based on Schauder's and Darbo's fixed point theorems. In particular, to apply Schauder's fixed point theorem based method, a special care is devoted to the proof of the L ^p -compactness of the operators associated with our nonlinear quadratic integral equations. The second goal of this work is to study a numerical method for solving nonlinear Volterra integral equations of a fairly general type. Finally, we provide the reader with some examples that illustrate the different results of this work.