Abstract:
We consider the Cauchy problem for a model third-order partial differential equation with non-linearity of the form
$|\nabla u|^q$. We prove that for $q\in(1,2]$ the Cauchy problem in $\mathbb{R}^2$ has no local-in-time weak
solution for a large class of initial functions, while for $q>2$ a local weak solution exists.