On classical solutions and canonical transformations for Hamilton--Jacobi--Bellman equations
Mohit Bansil, Alpár R. Mészáros
TL;DR
The paper addresses global classical solvability of Hamilton--Jacobi--Bellman equations beyond the fully convex regime by leveraging a family of upper-triangular canonical transformations $ (x,p)\mapsto (x,p-\alpha x) $. It shows that the HJB is invariant under this transform and that appropriate $\alpha$ can convexify transformed data $H_\alpha$ and $G_\alpha$, yielding global $C^{1,1}_{loc}$ solvability for the original problem. Through complementary Lagrangian and Hamiltonian analyses, it derives explicit, verifiable derivative-based conditions (in terms of $\lambda_0$, $\lambda_H$, $\lambda_G$) that guarantee global well-posedness when $\alpha$ is large enough. This approach provides a new mechanism to extend global well-posedness results beyond the fully convex setting and suggests potential extensions to nonlinear transforms and mean-field game frameworks.
Abstract
In this note we show how canonical transformations reveal hidden convexity properties for deterministic optimal control problems, which in turn result in global existence of $C^{1,1}_{loc}$ solutions to first order Hamilton--Jacobi--Bellman equations.
