The Ekeland variational principle, formulated by Ivar Ekeland in 1972, is the foundation of modern variational calculus. Among its findings there are numerous and various applications which are developed and described in Ekeland Variational Principle with Variants and Generalizations, by Irina Meghea (University Politehnica, Bucharest): geometry of Banach spaces, nonlinear analysis, differential equations and partial differential equations, global analysis, probalistic analysis, differential geometry, fixed point theorem, nonlinear semi-groups, dynamic systems, optimization, mathematical programming and optimal control.
