“…Unfortunately, for the fully nonlinear setting, no reformulation is possible and the HJB PDE must be solved directly. In this direction, over the last years there has been a significant progress on the solution of high-dimensional HJB PDEs arising in optimal control, including max-plus algebra methods [34,1,11], sparse grids [18], tree-structure algorithms [4] and applications of artificial neural networks [25,12,33,35,49,38]. The above mentioned techniques can scale up to very high-dimensional HJB PDEs, however, the effective implementation of real-time HJB-based controllers remains an open problem.…”