Caristi type coincidence point theorem in topological spaces (Q1791382)

Summary: A generalized Caristi type coincidence point theorem and its equivalences in the setting of topological spaces by using a kind of nonmetric type function are obtained. These results are used to establish variational principle and its equivalences in \(d\)-complete spaces, bornological vector space, seven kinds of completed quasi-semimetric spaces equipped with \(Q\)-functions, uniform spaces with \(q\)-distance, generating spaces of quasimetric family, and fuzzy metric spaces.