рдбрд┐рд╕реЗрдВ реирежрезреи ┬╖ Progress in Nonlinear Differential Equations and Their ApplicationsрдкреБрд╕реНрддрдХ 24 ┬╖ Springer Science & Business Media
Many boundary value problems are equivalent to Au=O (1) where A : X --+ Y is a mapping between two Banach spaces. When the problem is variational, there exists a differentiable functional rand inf.