A quantitative Hopf-Oleinik lemma for degenerate fully nonlinear operators and applications to free boundary problems

Davide Giovagnoli, Enzo Maria Merlino, Diego Moreira

We prove a quantitative inhomogeneous Hopf-Oleinik lemma for viscosity solutions of $$|\nabla u{|}^{\hat{I}}\pm F(D^{2}u)=f$$ and, more generally, for viscosity supersolutions of $|\nabla u|^Î…