Critical points of solutions to the obstacle problem in the plane
Star shaped coincidence sets in the obstacle problem
Concavity properties of solutions to some degenerate quasilinear elliptic Dirichlet problems
Symmetry of minimizers with a level surface parallel to the boundary
We consider the functional where is a bounded domain and is a convex function. Under general assumptions on , Crasta [Cr1] has shown that if admits a minimizer in depending only on the distance from the boundary of , then must be a ball. With some restrictions on , we prove that spherical symmetry can be obtained only by assuming that the minimizer has one level surface parallel to the boundary (i.e. it has only a level surface in common with the distance). We then discuss how these...
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