Obstacle problem for a non-convex fully nonlinear operator.

Abstract In this paper, we study a priori C 2 , α estimate up to the boundary for F (D 2 u) = 0 and the regularity of the free boundary of the obstacle problem for fully nonlinear operator under specific conditions for the operator and level sets of the operator. The conditions are variations of conditions for the zero set of the operator in [7]. [ABSTRACT FROM AUTHOR]