The paper is concerned with a scalar balance law, where the source term depends on a control function Formula: see text. Given a control Formula: see text, it is proved that, for generic initial data Formula: see text, the solution has finitely many shocks, interacting at most two at a time. Moreover, at the terminal time Formula: see text no shock interaction occurs and no new shock is formed. In addition, a family of optimal control problems is considered, including a running cost and a terminal cost. An example is constructed where the optimal solution contains two shocks merging exactly at the terminal time Formula: see text. Such behavior persists under any suitably small perturbation of the flux, source and cost functions, and of the initial data. This shows that generic solutions of optimization problems have different qualitative properties, compared with generic solutions to Cauchy problems.
Bressan et al. (Fri,) studied this question.