Hamilton-Jacobi Reachability

Set-valued safety analysis for nonlinear dynamical systems. Each project here computes a reachable set or tube on the joint state space: the answer is not "this trajectory is safe," it is "this entire region of state space admits a control policy that stays safe."

Implemented with helperOC (Mo Chen, UC Berkeley) on top of the level-set library, plus a custom YAPPS-style trajectory-optimisation comparison for the Dubins-airplane case.