On a Degenerate Nonlocal Parabolic Problem Describing Infinite Dimensional Replicator Dynamics

We establish the existence of locally positive weak solutions to the homogeneous Dirichlet problem for ut = u∆u + u ∫ Ω |∇u| in bounded domains Ω ⊂ R which arises in game theory. We prove that solutions converge to 0 if the initial mass is small, whereas they undergo blow-up in finite time if the initial mass is large. In particular, it is shown that in this case the blow-up set coincides with Ω, i.e. the finite-time blow-up is global.