Não disponível

It is studied the relationship between the solutions of the linear functional differential equation (1) d / dt Px_t = Lx_tand its perturbed equation d / dt [Dx_t - G(t, x_t)] = Lx_t + F(t, x,_t) and it is proved, under certain hypotheses on G(t, φ) and F(t, φ), that if μ ∈ R is a double characteristic root of (1) such that there is no other characteristic root of (l) with Reλ ≥ μ, then there are two solutions x₁(t) and x₂(t) of (2) such that x₁(t) → e^μt and x_{2μt as t &rarr ∞.}