The control and estimation of continuous-time/continuous-space nonlinear systems continues to be a challenging problem, and this is one of the c- tral foci of this book. A common approach is to use dynamic programming; this typically leads to solution of the control or estimation problem via the solution of a corresponding Hamilton Jacobi (HJ) partial di?erential eq- tion (PDE). This approach has the advantage of producing the optimal control. (The term optimal has a somewhat more complex meaning in the class of H problems. However, we will freely use the term for such controllers ?...