Optimal Control of Markov Processes with Age-Dependent Transition Rates
  We study optimal control of Markov processes with age-dependent transition rates. The control policy is chosen continuously over time based on the state of the process and its age. We study infinite horizon discounted cost and infinite horizon average cost problems. Our approach is via the construction of an equivalent semi-Markov decision process. We characterize the value function and optimal controls for both discounted and average cost cases. 
Mrinal K. Ghosh and Subhamay Saha
math.OC