Special Session 14: New perspectives in the qualitative study of nonlinear differential equations and dynamical systems

Liouville-type results for the Fisher-KPP equation: old and new
Luca Rossi
Sapienza University of Rome
Italy
Co-Author(s):    
Abstract:
In this talk, we present a joint work with O. Tough on the existence and uniqueness of positive bounded stationary solutions to the Fisher-KPP equation in unbounded domains, with Dirichlet boundary conditions. Under strong KPP-type assumptions, we derive a necessary and sufficient condition for existence in dimensions $\leq 6$, expressed in terms of the generalized principal eigenvalue. We further show that, whenever it exists, the solution is unique. As an application, one infers that for branching Brownian motion, global survival implies local survival in low dimensions.