Flow invariance for solutions to nonlinear nonautonomous partial differential delay equations ✩

We investigate the problem of existence and flow invariance of mild solutions to nonautonomous partial differential delay equations ˙u(t) + B(t)u(t) F (t, ut ), t s, us = ϕ, where B(t) is a family of nonlinear multivalued, α-accretive operators with D(B(t)) possibly depending on t, and the operators F (t, .) being defined—and Lipschitz continuous—possibly only on “thin” subsets of the initial history space E. The results are applied to population dynamics models. We also study the asymptotic behavior of solutions to this equation. Our analysis will be based on the evolution operator associated to the equation in the initial history space E.