Some results on measurability
of multivalued mappings are given. Then using them, the following random fixed
point theorem is proved; Theorem. Let X be a Polish space, (T,𝒜) a measurable
space. Let F : T × X → CB(X) be a mapping such that for each x ∈ X, F(⋅,x) is
measurable and for each t ∈ T, F(t,⋅) is k(t)-contraction, where k : T → [0,1) is
measurable. Then there exists a measurable mapping u : T → X such that for every
t ∈ T, u(t) ∈ F(t,u(t)).
|