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Register a new userCharacterizing compact coincidence sets in the obstacle problem -- a short proof
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Motivated by the almost completely open problem of characterizing unbounded coincidence sets of global solutions of the classical obstacle problem in higher dimensions, we give in this note a concise and easy-to-extend proof of the known fact that if the coincidence set ${u=0 }$ of a global solution $u$ is bounded with nonempty interior then it is an ellipsoid.
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