HAMILTON-JACOBI EQUATIONS WITH SINGULAR BOUNDARY-CONDITIONS ON A FREE-BOUNDARY AND APPLICATIONS TO DIFFERENTIAL-GAMES

A class of Hamilton-Jacobi equations arising in generalized time-optimal control problems and differential games is considered. The natural global boundary value problem for these equations has a singular boundary condition on a free boundary. The uniqueness of the continuous solution and of the free boundary is proved in the framework of viscosity solutions. A local uniqueness theorem is also given, as well as some existence results and several applications to control and game theory. In particular a relaxation theorem (weak form of the bang-bang principle) is proved for a class of nonlinear differential games.