A Note on Free Boundary Problems on RCD(K,N)-spaces

Abstract: This note is devoted to prove the following results on RCD(K,N)-spaces: 1) minimizers of one-phase Bernoulli problems are locally Lipschitz continuous; 2) minimizers of classical obstacle problems are quadratic growth away from the free boundary. Recently, both of these two results were obtained on non-collapsed RCD(K,N)-spaces; see [13,23]. This note will prove these two results without assuming that the ambient space is non-collapsed. We also include a proof of nondegeneracy of minimizers and locally finiteness of perimeter of their free boundaries for two-phase Bernoulli problems.