Multivalued Mappings with the Quasimöbius Property

We continue studying the multivalued mappings of BAD (bounded angular distortion) class in Ptolemaic Möbius structures. We prove that the single-valued branches of these mappings are quasimöbius under some constraints on the metric spaces. Some conditions are found that guarantee the upper semicontinuity and continuity of BAD multivalued mappings.

     

Banach空间中两个多值非扩张映射不动点的迭代逼近问题

研究了两个多值非扩张映射的公共不动点的迭代逼近问题.利用Hausdoff度量,引入了一类新的Ischikawa型迭代,在一致凸的Banach空间里,证明了在某些条件下,此迭代序列强收敛到多值非扩张映射的公共不动点.改进和推广了文献的相关结果.     

Best proximity points: global minimization of multivalued non-self mappings

In this article, we give a best proximity point theorem for generalized contractions in metric spaces with appropriate geometric property. We also, give an example which ensures that our result cannot be obtained from a similar result due to Amini-Harandi (Best proximity points for proximal generalized contractions in metric spaces. Optim Lett, 2012). Moreover, we prove a best proximity point theorem for multivalued non-self mappings which generalizes the Mizoguchi and Takahashi’s fixed point theorem for multivalued mappings.     

KKM mappings in metric type spaces

In this work we discuss some recent results about KKM mappings in cone metric spaces. We also discuss the fixed point existence results of multivalued mappings defined on such metric spaces. In particular we show that most of the new results are merely copies of the classical ones and do not necessitate the underlying Banach space nor the associated cone.     

Fixed point theorems of multivalued monotone mappings in ordered metric spaces

In this work, some new fixed point and coupled fixed point theorems for multivalued monotone mappings in ordered metric spaces are proved.     

Multivalued generalized nonlinear contractive maps and fixed points

We introduce some notions of generalized nonlinear contractive maps and prove some fixed point results for such maps. Consequently, several known fixed point results are either improved or generalized including the corresponding recent fixed point results of Ciric [L.B. Ciric, Multivalued nonlinear contraction mappings, Nonlinear Anal. 71 (2009) 2716-2723], Klim and Wardowski [D. Klim, D. Wardowski, Fixed point theorems for set-valued contractions in complete metric spaces, J. Math. Anal. Appl. 334 (2007) 132-139], Feng and Liu [Y. Feng, S. Liu, Fixed point theorems for multivalued contractive mappings and multivalued Caristi type mappings, J. Math. Anal. Appl. 317 (2006) 103-112] and Mizoguchi and Takahashi [N. Mizoguchi, W. Takahashi, Fixed point theorems for multivalued mappings on complete metric spaces, J. Math. Anal. Appl. 141 (1989) 177-188].     

Minimum of a functional in a metric space and fixed points

The existence of minimizers is examined for a function defined on a metric space. Theorems are proved that assert the existence of minimizers, and examples of the functions for which these theorems are valid are given. Then, these theorems are applied to proving theorems on fixed points of univalent and multivalued mappings of metric spaces. Finally, coincident points of two mappings are examined.     

An application of a fixed point theorem to best simultaneous approximation

Using a recent result regarding the fixed points of multivalued mappings, the existence of invariant best simultaneous approximation in chainable metric space is proved.     

Best approximation theorems for nonexpansive and condensing mappings in hyperconvex spaces

In hyperconvex metric spaces we consider best approximation, invariant approximation and best proximity pair problems for multivalued mappings that are condensing or nonexpansive.     

集值半连续映射对的公共不动点定理

本文旨在将B.Fisher关于完备度量空间中映射对的公共不动点推广到Hausdotff度量下集值上半连续映射对的情形,得到了定理3,推论5.8.引理7是关于Hausdorff度量的新结果。     

Fixed point theorems of upper semicontinuous multivalued mappings with applications in hyperconvex metric spaces

In the present paper, we establish two fixed point theorems for upper semicontinuous multivalued mappings in hyperconvex metric spaces and apply these to study coincidence point problems and minimax problems.     

完备度量空间中集值映象的几个不动点定理

研究了完备度量空间中集值映象序列的不动点性质，得到了几个新的不动点定理，并指出了参考文献中的一个错误．     

Fixed points, selections and common fixed points for nonexpansive-type mappings

We study the existence of fixed points in the context of uniformly convex geodesic metric spaces, hyperconvex spaces and Banach spaces for single and multivalued mappings satisfying conditions that generalize the concept of nonexpansivity. Besides, we use the fixed point theorems proved here to give common fixed point results for commuting mappings.     

Fixed point results for new type of multivalued mappings in bounded metric spaces with an application

In this paper, we prove some fixed point results for multivalued mappings in bounded metric spaces via symmetric spaces. Moreover an application to an integral inclusion is given.

     

Common fixed points of a nonexpansive semigroup and a convergence theorem for Mann iterations in geodesic metric spaces

First, we consider a strongly continuous semigroup of nonexpansive mappings defined on a closed convex subset of a complete CAT(0) space and prove a convergence of a Mann iteration to a common fixed point of the mappings. This result is motivated by a result of Kirk (2002) and of Suzuki (2002). Second, we obtain a result on limits of subsequences of Mann iterations of multivalued nonexpansive mappings on metric spaces of hyperbolic type, which leads to a convergence theorem for nonexpansive mappings on these spaces.     

Some fixed point theorems for multivalued mappings concerning <Emphasis Type="Italic">F</Emphasis>-contractions

The aim of this paper is to prove some fixed point theorems for multivalued maps satisfying different inequalities based on Wardowski’s technique in complete metric spaces. Our results extend and generalize several known results in the literature. We also give an application to the existence of fixed points for a class of Lipschitz multivalued mappings with a constant being greater than 1. Examples are also given to illustrate our results.     

A note on Robinson–Ursescu and Lyusternik–Graves theorem

The aim of this note is twofold. First, we prove an analogue of the well-known Robinson–Ursescu Theorem on the relative openness with a linear rate (restrictive metric regularity) of a multivalued mapping. Second, we prove a generalization of Graves Open Mapping Theorem for a class of mappings which can be approximated at a reference point by a bunch of linear mappings. The approximated non-linear mapping is restricted to a closed convex subset of a Banach space.     

Fixed point theorems for multivalued non-linear $F$-contractions on quasi metric spaces with an application

In this paper, we introduce $(\alpha,\beta)$-type $F-\tau$ contraction and utilize the same to prove some fixed point results for multivalued mappings in quasi metric spaces. Furthermore, we furnish with some examples to exhibit the utility of our results. As an application, we establish the existence of a solution for a non-linear integral equation.     

Multivalued mappings

The present paper is a survey of the contemporary state of art in the theory of multivalued mappings. In it one considers different forms of continuity of multivalued mappings, one investigates differentiable and measurable multivalued mappings, one considers single-valued continuous approximations and sections of multivalued mappings, one studies fixed points of multivalued mappings and other questions of this theory. One gives references to the literature regarding applications to the theory of games, mathematical economics, the theory of differential inclusions and generalized dynamical systems. The paper contains an extensive bibliography.Translated from Itogi Nauki i Tekhniki, Seriya Matematicheskii Analiz, Vol. 19, pp. 127–230, 1982.     

Banach空间中单值非扩张映射和多值非扩张映射公共不动点混合迭代逼近研究

引入了两个单值非扩张映射与两有限族多值非扩张映射新的混合迭代,在Banach空间中,研究了两个单值非扩张映射与两有限族多值非扩张映射在新迭代下关于公共不动点的收敛性,改进和推广了已有文献相关的结果.