Abstract
In this paper, we establish sufficient conditions for the existence of solutions of equilibrium problems in a metric space, that do not involve any convexity assumption either for the domain or for the function. To prove these results, a weak notion of semicontinuity is considered. Furthermore, some existence results for systems of equilibrium problems are provided.
Acknowledgements
This work has been supported by the National Research Programme PRIN 20079PLLN7 ‘Nonlinear Optimization, Variational Inequalities, and Equilibrium Problems’.