Threshold behavior and non-quasiconvergent solutions with localized initial data for bistable reaction-diffusion equations

Abstract. We consider bounded solutions of the semilinear heat equation ut = uxx + f(u) on R, where f is of the unbalanced bistable type. We examine the ω-limit sets of bounded solutions with respect to the locally uniform convergence. Our goal is to show that even for solutions whose initial data vanish at x = ±∞, the ω-limit sets may contain functions which are not steady states. Previously, such examples were known for balanced bistable nonlinearities. The novelty of the present result is that it applies to a robust class of nonlinearities. Our proof is based on an analysis of threshold solutions for ordered families of initial data whose limits at infinity are not necessarily zeros of f . We consider bounded solutions of the semilinear heat equation ut = uxx + f(u) on R, where f is of the unbalanced bistable type. We examine the ω-limit sets of bounded solutions with respect to the locally uniform convergence. Our goal is to show that even for solutions whose initial data vanish at x = ±∞, the ω-limit sets may contain functions which are not steady states. Previously, such examples were known for balanced bistable nonlinearities. The novelty of the present result is that it applies to a robust class of nonlinearities. Our proof is based on an analysis of threshold solutions for ordered families of initial data whose limits at infinity are not necessarily zeros of f .