An escape time interpretation of robust control

Abstract

This paper studies the problem of an agent who wants to prevent the state from exceeding a critical threshold. Even though the agent is presumed to know the model, the optimal policy is computed by solving a conventional robust control problem. That is, robustness is induced here by objectives rather than uncertainty, and so is an example of the duality between risk-sensitivity and robustness. However, here the agent only incurs costs upon escape to a critical region, not during 'normal times'. We argue that this is often a more realistic model of macroeconomic policymaking.