A Unified Fixed Point Theory in Generalized Convex Spaces

Abstract

Let \({\mathfrak {B}}\)be the class of ‘better’ admissible multimaps due to the author. We introduce new concepts of admissibility (in the sense of Klee) and of Klee approximability for subsets of G-convex uniform spaces and show that any compact closed multimap in\({\mathfrak {B}}\)from a G-convex space into itself with the Klee approximable range has a fixed point. This new theorem contains a large number of known results on topological vector spaces or on various subclasses of the class of admissible G-convex spaces. Such subclasses are those of Φ-spaces, sets of the Zima–Hadžic type, locally G-convex spaces, and LG-spaces. Mutual relations among those subclasses and some related results are added.