화학공학소재연구정보센터
SIAM Journal on Control and Optimization, Vol.53, No.4, 1789-1814, 2015
VANISHING DISCOUNT LIMIT AND NONEXPANSIVE OPTIMAL CONTROL AND DIFFERENTIAL GAMES
A classical problem in ergodic control consists of studying the limit behavior of the optimal value V-lambda of a discounted cost functional with infinite horizon as the discount factor lambda tends to zero. In the literature, this problem has been addressed under various conditions ensuring that the rescaled value function lambda V-lambda converges uniformly to a constant limit. The main goal of this paper is to study this problem without such conditions, so that the aforementioned limit need not be constant. So, under a nonexpansivity assumption, we derive Lipschitz bounds which yield compactness of {lambda V-lambda} for both control systems and differential games. Then, we study the convergence of solutions to Hamilton-Jacobi equations under the hypothesis that the Hamiltonian is radially nondecreasing, hence allowing for the existence noncoercivity directions. Using PDE methods, we show that the convergence is monotone and we characterize the limit as the maximal subsolution of a certain Hamilton-Jacobi equation. Finally, we return to optimal control problems and differential games for nonexpansive dynamics obtaining explicit representation formulas for the uniform limit of lambda V-lambda as lambda -> 0.