Gradient ascend method for fully nonlinear parabolic differential equations with convex nonlinearity

We introduce a generic numerical schemes for fully nonlinear parabolic PDEs on the full domain, where the nonlinearity is convex on the Hessian of the solution. The main idea behind this paper is reduction: we reduce the fully nonlinear problem to a series of simpler semilinear ones parameterized by the diffusion term and take the maximum over the solution of those problems through a novel gradient ascend method on the diffusion coefficient that we introduced for such semilinear PDEs. The promise of this study is a step toward the proof-of-concept that for any arbitrary numerical scheme for semilinear parabolic PDEs, one can build an iterative methods based on gradient ascent to converge to the solution of a fully nonlinear problem. Therefore, investment in our effort to create more efficient semilinear PDEs leads to efficiency for fully nonlinear PDEs. We leverage the theoretical results of Soner et al. 2012 to obtain numerical schemes for fully nonlinear PDEs and to justify the convergence in our methodology. The method is tested in a numerical experiment on the fully problem of portfolio optimization under stochastic volatility model.