Resumen de Fixed points of the contractiveor expansive type for multivalued mappings: toward a unified approach

Jaime Rodríguez Montes

• A condition on the functions ' : R+ ! R+ = [0, +1) which, for single valued maps, has proved useful in asserting the existence of fixed points for contractions or expansions relative to either distances or w-distances, is now used to examine the behaviour of multivalued mappings. Since it applies equally to both contracting ('(t) < t for t > 0) or expanding maps ('(t) > t for all t > 0), it also allows, to some extent, a unified approach to both types of problems.