The Second Order Estimate for Fully Nonlinear Uniformly Elliptic Equations without Concavity Assumption

G. C. Dong, B. J. Bian, Z. C. Guan

Investigating for interior regularity of viscosity solutions to the fully nonlinear elliptic equation $$F(x,u,▽u,{▽}^{2}u)=0,$$ we establish the interior $C^…