Abstract
In this paper we prove the existence and multiplicity of (weak) solutions for the following fractional boundary value problem: where , (0) D (t) (alpha-1) and (t) D (T) (alpha-1) are the left and right Riemann-Liouville fractional integrals of order 1 - alpha respectively, lambda,mu a [0,+a), T > 0, F,G a C([0,T] x R (N) ;R)\{0} and A = (a (ij) (t)) (NxN) is symmetric. Our approach is based on variational methods.