Sobre las soluciones periódicas del problema de Dirichlet para ecuaciones de tipo parabólico

 It is shown that for a Dirichlet's periodic problema studied by Lazer:

L(u) = g(x,t,u)+f₁(x,t)+s𝜙(x,t)  in Ω xR

    u(x,t+T) ≡ u(x,t),  u|∂ Ω xR= 0

where Ω is a bounded domain in R^N,and certain restrictions are assumed for g, f₁, and 𝜙, there exists a number  ∝(f₁) such that the problem has at least two solution if s < ∝(f₁), and at least one if s = ∝(f₁).