duality and perturbation methods in critical point theory What to say and what to do when mostly your friends love reading? Are you the one that don't have such hobby? So, it's important for you to… (More)

We compare some recent results on bounded solutions (over Z) of nonlinear difference equations and systems to corresponding ones for nonlinear differential equations. Bounded input-bounded output… (More)

The Leray–Schauder degree is defined for mappings of the form I−C, where C is a compact mapping from the closure of an open bounded subset of a Banach space X into X. Since the fifties, a lot of work… (More)

*This work was realized during a stay of the second author in Louvain-la Neuve, being supported by the Ministry of Education and Culture (Spain). He wants to thank here the Département de… (More)

A class of linear operators L+λI between suitable function spaces is considered, when 0 is an eigenvalue of L with constant eigenfunctions. It is proved that L + λI satisfies a strong maximum… (More)

ABSTRACT. T-periodic solutions of systems of differential equations of the form (φ(u′))′ = ∇uF (x, u) + h(x) where φ = ∇Φ, with Φ strictly convex, is a homeomorphism of the ball Ba ⊂ R n onto Rn, are… (More)

The associated optimization task is to find a realization (A, b, c) of H(z) to minimize S(A, b, c). In 9.1, a gradient flow is constructed and the existence of optimization is proved. In 9.2, an… (More)

A continuation theorem introduced in [39] and developed in [40] in the frame of a degree theory for mappings of the type L + N between normed vector spaces, with L Fredholm of index zero and N… (More)

Using Brouwer degree, we prove a more general version of the zero exclusion principle for families of polynomials and apply it to obtain very simple proofs of extensions of recent results on the… (More)