H?lder regularity for non-variational porous media type equations

We present a Krylov-Safonov theory approach for the Holder regularity of viscosity solutions to nonvariational porous media type equations. We explore the peculiarity of this type of problem: either the equation falls in a uniformly elliptic regime or the eikonal mechanism takes care of the regularity. Our techniques are based on sliding paraboloids resulting in an ABP-type measure estimate. By combining such estimates, a diminishing of oscillation property is available, resulting in a regularity control in Holder spaces. (c) 2023 Elsevier Inc. All rights reserved.