Application of fixed point theorem to best simultaneous approximation in convex metric spaces
The paper contains some applications of the notion of sets to several classes of operators on Banach lattices. In particular, we introduce and study the class of order -Dunford-Pettis operators, that is, operators from a Banach space into a Banach lattice whose adjoint maps order bounded subsets to an sets. As a sequence characterization of such operators, we see that an operator from a Banach space into a Banach lattice is order -Dunford-Pettis, if and only if for for every weakly null...
In the present paper initial operators for a right invertible operator, which are induced by sequential shifts and have the property c(R) are constructed. An application to the Lagrange type interpolation problem is given. Moreover, an example with the Pommiez operator is studied.
We recall a recent extension of the classical Banach fixed point theorem to partially ordered sets and justify its applicability to the study of the existence and uniqueness of solution for fuzzy and fuzzy differential equations. To this purpose, we analyze the validity of some properties relative to sequences of fuzzy sets and fuzzy functions.