EN
We investigate the existence of solutions of the Dirichlet problem for the differential inclusion $0 ∈ Δ x(y) + ∂_{x}G(y,x(y))$ for a.e. y ∈ Ω, which is a generalized Euler-Lagrange equation for the functional $J(x) = ∫_{Ω}{ 1/2|∇x(y)|² - G(y,x(y))}dy$. We develop a duality theory and formulate the variational principle for this problem. As a consequence of duality, we derive the variational principle for minimizing sequences of J. We consider the case when G is subquadratic at infinity.