Extended f-Vector Equilibrium Problem

We introduce and study extended f-vector equilibrium problem. By using KKM-Fan Theorem as basic tool, we prove existence theorem in the setting of Hausdorff topological vector space and reflexive Banach space. Some examples are also given.

Periodic solutions of a quasilinear wave equations with variable coefficients.

We prove existence theorem for periodic in time solutions of quasilinear wave level of variable coefficients and homogeneous boundary conditions, one of which is a Neumann condition.