Structured Solution Methods for Non-Markovian Decision Processes

Fahiem Bacchus
Department of Computer Science
University of Waterloo
Waterloo, ON, CANADA N2L 3G1
email: fbacchus@logos.uwaterloo.ca

Craig Boutilier
Department of Computer Science
University of British Columbia
Vancouver, BC, CANADA, V6T 1Z4
email: cebly@cs.ubc.ca

Adam Grove
NEC Research Institute
4 Independence Way
Princeton NJ 08540, USA
email: grove@research.nj.nec.com

Abstract
Markov Decision Processes (MDPs), currently a popular method for modeling and solving decision theoretic planning problems, are limited by the Markovian assumption: rewards and dynamics depend on the current state only, and not on previous history. Non-Markovian decision processes (NMDPs) can also be defined, but then the more tractable solution techniques developed for MDP's cannot be directly applied. In this paper, we show how an NMDP, in which temporal logic is used to specify history dependence, can be automatically converted into an equivalent MDP by adding appropriate temporal variables. The resulting MDP can be represented in a structured fashion and solved using structured policy construction methods. In many cases, this offers significant computational advantages over previous proposals for solving NMDPs.

To appear, AAAI-97, Providence, RI

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