Title
Simplex Algorithm for Countable-State Discounted Markov Decision Processes
Abstract
We consider discounted Markov decision processes (MDPs) with countablyinfinite state spaces, finite action spaces, and unbounded rewards. Typical examples of such MDPs are inventory management and queueing control problems in which there is no specific limit on the size of inventory or queue. Existing solution methods obtain a sequence of policies that converges to optimality in value but may not improve monotonically, i.e., a policy in the sequence may be worse than preceding policies. Our proposed approach considers countably-infinite linear programming (CILP) formulations of the MDPs (a CILP is defined as a linear program (LP) with countably-infinite numbers of variables and constraints). Under standard assumptions for analyzing MDPs with countably-infinite state spaces and unbounded rewards, we extend the major theoretical extreme point and duality results to the resulting CILPs. Under additional mild assumptions, which are satisfied by several applications of interest, we present a simplex-type algorithm that is implementable in the sense that each of its iterations requires only a finite amount of data and computation. We show that the algorithm finds a sequence of policies that improves monotonically and converges to optimality in value. Unlike existing simplex-type algorithms for CILPs, our proposed algorithm solves a class of CILPs in which each constraint may contain an infinite number of variables and each variable may appear in an infinite number of constraints. A numerical illustration for inventory management problems is also presented.
Year
DOI
Venue
2017
10.1287/opre.2017.1598
OPERATIONS RESEARCH
Keywords
Field
DocType
simplex algorithm,infinite linear programs,dynamic programming
Extreme point,Dynamic programming,Mathematical optimization,Countable set,Simplex algorithm,Markov decision process,Duality (optimization),Queueing theory,Linear programming,Mathematics
Journal
Volume
Issue
ISSN
65
4
0030-364X
Citations 
PageRank 
References 
3
0.43
5
Authors
4
Name
Order
Citations
PageRank
Ilbin Lee131.44
Marina A. Epelman220918.62
H. Edwin Romeijn376983.88
Robert L. Smith4664123.86