Let $\Omega$ be a domain, $u$ and $f$ are real valued functions on $\Omega$, $(u_{ij})$ is the Hessian matrix of $u$. The function $f$ may change sign: that said, do there exist solutions for the following equation? $$ \det u_{ij}=f $$
1 Answer
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In general nothing is known. Only local solvability is known for some special cases.
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$\begingroup$ Thank you! Could you give me some references? $\endgroup$– lidingCommented Nov 16, 2019 at 20:22
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$\begingroup$ The first page of this paper summarizes what little is known in the 2-dimensional case. Some of this can be extended to higher dimensions. $\endgroup$ Commented Nov 16, 2019 at 21:55
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$\begingroup$ Sorry, Could you give me the title of this paper? $\endgroup$– lidingCommented Nov 17, 2019 at 0:39
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$\begingroup$ Sorry about that. Here's the link: arxiv.org/abs/1003.2241. Another one is arxiv.org/abs/1204.6704 $\endgroup$ Commented Nov 17, 2019 at 21:22
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