  For a vehicle on an assigned path, we find the minimum-time speed law that
satisfies kinematic and dynamic constraints, related to maximum speed and
maximum tangential and transversal acceleration. We present a necessary and
sufficient condition for the feasibility of the problem and a simple operator,
based on the solution of two ordinary differential equations, which computes
the optimal solution. Theoretically, we show that the problem feasible set, if
not empty, is a lattice, whose supremum element corresponds to the optimal
solution.
