Introduction and Summary.- Part I: Finite Model Approximations in Stochastic Control.- Prelude to Part I.- Finite Action Approximation of Markov Decision Processes.- Finite-State Approximation of Markov Decision Processes.- Approximations for Partially Observed Markov Decision Processes.- Approximations for Constrained Markov Decision Problems.- Part II: Finite Model Approximations in Decentralized Stochastic Control.- Prelude to Part II.- Finite...