Skip to main content
6 events
when toggle format what by license comment
May 15, 2022 at 4:36 vote accept ling
May 15, 2022 at 4:30 comment added ling Oh, I understand what you mean. In your example, $a_{ij}$ could be discontinuous and we could guling coefficients to construct a locally uniformly elliptic equation. Then there comes a question is that if we can assume some conditions on $a_{ij}$ to make this problem still true, is it must be uniformly elliptic? Thank you very much for your warm answer.
May 15, 2022 at 3:26 comment added Connor Mooney To clarify, the positive and negative Hessian eigenvalues of $u$ are locally bounded away from $0$ and $\pm \infty$ outside $B_{1/4}$ (where the equation is already uniformly elliptic), so one can cook up locally uniformly elliptic coefficients on the plane such that $u$ solves the corresponding equation.
May 15, 2022 at 2:55 comment added Connor Mooney Since $\det D^2u < 0$ outside of $B_{1/4}$, $u$ solves a locally uniformly elliptic equation on the whole plane.
May 15, 2022 at 2:47 comment added ling Thanks for your answer, it’s so excited for me to have your answer. I am using your notes to study Monge-ampere equation. As for the question, I want to know if it is right for $a_{ij}$ just strictly elliptic but not uniformly elliptic. In your counterexample, the equation is degenerate at $x=\pm\sqrt{2}/2$. Is it could be true if we allow the degeneration only at $\infty$? I think it maybe right, but I have no idea how to prove it. Thank you again for your answer!
May 14, 2022 at 14:29 history answered Connor Mooney CC BY-SA 4.0