Abstract Convexity,Some Relations and Applications

The aim of this article is to analyze the relationship between various notions of abstract convexity structures that we find in the literature, in connection with the problem of the existence of continuous selections and fixed points of correspondences. We focus mainly on the notion of mc -spaces, which was introduced in J.V. LLinares (1998). Unified treatment of the problem of the existence of maximal elements in binary relations: a characterization. Journal of Mathematical Economics , 29 , 285-302], and its relationship with c -spaces Ch.D. Horvath (1991). Contractibility and generalized convexity. Journal of Mathematical Analysis and Applications , 156 , 341-357], simplicial convexity R. Bielawski (1987). Simplicial convexity and its applications. Journal of Mathematical Analysis and Applications , 127 , 155-171], order convexity (used in Ch.D. Horvath and J.V. LLinares (1996). Maximal elements and fixed points for binary relations on topological ordered spaces. Journal of Mathematical Economics , 25 , 291-306]), B '-simplicial convexity and L -spaces H. Ben-El-Mechaiekh, S. Chebbi, M. Florenzano and J.V. LLinares (1998). Abstract convexity and fixed points. Journal of Mathematical Analysis and Applications , 222 , 138-150]. Moreover, in the context of mc -spaces, a characterization result of nonempty finite intersection, in the line with the Knaster-Kuratowski-Mazurkiewicz Lemma, some consequences of it and some generalizations of Browder's existence of continuous selection and fixed point theorem are presented.