Regularity of the free boundary for the two-phase Bernoulli problem
Guido De Philippis, Luca Spolaor, Bozhidar Velichkov · Inventiones mathematicae · 2021
Abstract We prove a regularity theorem for the free boundary of minimizers of the two-phase Bernoulli problem, completing the analysis started by Alt, Caffarelli and Friedman in the 80s. As a consequence, we also show regularity of minimizers of the multiphase spectral optimization problem for the principal eigenvalue of the Dirichlet Laplacian.