Uniqueness of Weak Solutions to One-Dimensional Doubly Degenerate Cross-Diffusion System
Xiuqing Chen, Bang Du
TL;DR
This work proves the uniqueness of global weak solutions for a one-dimensional doubly degenerate cross-diffusion system modeling feeding bacteria in nutrient-poor environments, under the condition $1/u^0\in L^1(\Omega)$. The authors introduce the antiderivative $w(t,x)=\int_0^x (u+v)\,dy$, which converts the problem into a coupled $(w,v)$ framework and enables energy-type estimates. The main contribution is a two-stage estimate that bounds $\|w_1-w_2\|_{L^2}$ and $\|v_1-v_2\|_{L^2}$, leveraging mollification, boundary cancellations, and a Gronwall argument to deduce uniqueness. This advances the mathematical understanding of cross-diffusion systems in low dimensions and provides insight into the bacterial dynamics in malnourished environments.
Abstract
The uniqueness of global weak solutions to one-dimensional doubly degenerate cross-diffusion system is shown. The equations model the evolution of feeding bacterial populations in a malnourished environment. The key idea of the proof is applying anti-derivative of the sum of weak solutions to the system.
