-commuting maps and invariant approximations.
Caractérisations de la convergence locale de la méthode des approximations successives
Caristi's fixed point theorem and its equivalences in fuzzy metric spaces
In this article, we extend Caristi's fixed point theorem, Ekeland's variational principle and Takahashi's maximization theorem to fuzzy metric spaces in the sense of George and Veeramani [A. George , P. Veeramani, On some results in fuzzy metric spaces, Fuzzy Sets and Systems. 64 (1994) 395-399]. Further, a direct simple proof of the equivalences among these theorems is provided.
Caristi's fixed point theorem in probabilistic metric spaces
In this work, we define a partial order on probabilistic metric spaces and establish some new Caristi's fixed point theorems and Ekeland's variational principle for the class of (right) continuous and Archimedean t-norms. As an application, a partial answer to Kirk's problem in metric spaces is given.
Characterization for the convergence of Krasnoselskij iteration for non-Lipschitzian operators.
Characterizations of fixed points of nonexpansive mappings.
Characterizations of weakly compact sets and new fixed point free maps in c₀
We give a basic sequence characterization of relative weak compactness in c₀ and we construct new examples of closed, bounded, convex subsets of c₀ failing the fixed point property for nonexpansive self-maps. Combining these results, we derive the following characterization of weak compactness for closed, bounded, convex subsets C of c₀: such a C is weakly compact if and only if all of its closed, convex, nonempty subsets have the fixed point property for nonexpansive mappings.
Ćirić's fixed point theorem in a cone metric space.
Coincidence and fixed point theorems for functions in -KKM class on generalized convex spaces.
Coincidence and fixed point theorems for nonlinear hybrid generalized contractions
In this paper we first prove some coincidence and fixed point theorems for nonlinear hybrid generalized contractions on metric spaces. Secondly, using the concept of an asymptotically regular sequence, we give some fixed point theorems for Kannan type multi-valued mappings on metric spaces. Our main results improve and extend several known results proved by other authors.
Coincidence and fixed point theorems in metric and Banach spaces.
Coincidence and fixed points for compatible and relatively nonexpansive maps.
Coincidence and invariant approximation theorems for generalized -nonexpansive multivalued mappings.
Coincidence point and invariant approximation for mappings satisfying generalized weak contractive condition.
Coincidence point theorems for multivalued mappings.
Coincidence points and maximal elements of multifunctions on convex spaces
Generalized and unified versions of coincidence or maximal element theorems of Fan, Yannelis and Prabhakar, Ha, Sessa, Tarafdar, Rim and Kim, Mehta and Sessa, Kim and Tan are obtained. Our arguments are based on our recent works on a broad class of multifunctions containing composites of acyclic maps defined on convex subsets of Hausdorff topological vector spaces.
Coincidence theorems for nonlinear hybrid contractions.
Coincidence theorems for set-valued maps with g-kkm property on generalized convex space
In this paper, a set-valued mapping with G-KKM property is defined and a generalization of minimax theorem for set-valued maps with G-KKM property on generalized convex space is established. As a consequence of this results we verify the coincidence theorem for set-valued maps with G-KKM property on G-convex space. Finally, we apply our results to the best approximation problem and fixed point problem.
Coincidences and fixed points of reciprocally continuous and compatible hybrid maps.
Combinatorial lemmas for polyhedrons
We formulate general boundary conditions for a labelling to assure the existence of a balanced n-simplex in a triangulated polyhedron. Furthermore we prove a Knaster-Kuratowski-Mazurkiewicz type theorem for polyhedrons and generalize some theorems of Ichiishi and Idzik. We also formulate a necessary condition for a continuous function defined on a polyhedron to be an onto function.