From the Schauder fixed-point theorem to the applied multivalued Nielsen theory

A generalization of the Schauder fixed point theorem via multivalued contractions

We establish a fixed point theorem for a continuous function f : X → E, where E is a Banach space and X ⊆ E. Our result, which involves multivalued contractions, contains the classical Schauder fixed point theorem as a special case. An application is presented.

A Remark to the Schauder Fixed Point Theorem

In the paper some sufficient conditions are established in order that a continuous map have a fixed point. The results are related to those obtained by R. D. Nussbaum in [18], L. Górniewicz and D. RozpłochNowakowska in [12], S. Szufla in [21] and D. Bugajewski in [6]. The famous Schauder Fixed Point Theorem [20] has been generalized in various directions by using different methods. For referenc...

Epsilon Nielsen Fixed Point Theory

Let f : X → X be a map of a compact, connected Riemannian manifold, with or without boundary. For > 0 sufficiently small, we introduce an -Nielsen number N ( f ) that is a lower bound for the number of fixed points of all self-maps of X that are -homotopic to f . We prove that there is always a map g : X → X that is -homotopic to f such that g has exactlyN ( f ) fixed points. We describe proced...

Nielsen theory of transversal fixed point sets

Examples exist of smooth maps on the boundary of a smooth manifold M which allow continuous extensions over M without fixed points but no such smooth extensions. Such maps are studied here in more detail. They have a minimal fixed point set when all transversally fixed maps in their homotopy class are considered. Therefore we introduce a Nielsen fixed point theory for transversally fixed maps o...

Schauder Fixed Point Theorem in Spaces with Global Nonpositive Curvature