Stochastic Processes with Expected Stopping Time

Fuente: arXiv
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Main Authors: Chatterjee, Krishnendu, Doyen, Laurent
Format: Preprint
Published: 2021
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author Chatterjee, Krishnendu
Doyen, Laurent
author_facet Chatterjee, Krishnendu
Doyen, Laurent
contents Markov chains are the de facto finite-state model for stochastic dynamical systems, and Markov decision processes (MDPs) extend Markov chains by incorporating non-deterministic behaviors. Given an MDP and rewards on states, a classical optimization criterion is the maximal expected total reward where the MDP stops after T steps, which can be computed by a simple dynamic programming algorithm. We consider a natural generalization of the problem where the stopping times can be chosen according to a probability distribution, such that the expected stopping time is T, to optimize the expected total reward. Quite surprisingly we establish inter-reducibility of the expected stopping-time problem for Markov chains with the Positivity problem (which is related to the well-known Skolem problem), for which establishing either decidability or undecidability would be a major breakthrough. Given the hardness of the exact problem, we consider the approximate version of the problem: we show that it can be solved in exponential time for Markov chains and in exponential space for MDPs.
format Preprint
id arxiv_https___arxiv_org_abs_2104_07278
institution arXiv
publishDate 2021
record_format arxiv
spellingShingle Stochastic Processes with Expected Stopping Time
Chatterjee, Krishnendu
Doyen, Laurent
Logic in Computer Science
Markov chains are the de facto finite-state model for stochastic dynamical systems, and Markov decision processes (MDPs) extend Markov chains by incorporating non-deterministic behaviors. Given an MDP and rewards on states, a classical optimization criterion is the maximal expected total reward where the MDP stops after T steps, which can be computed by a simple dynamic programming algorithm. We consider a natural generalization of the problem where the stopping times can be chosen according to a probability distribution, such that the expected stopping time is T, to optimize the expected total reward. Quite surprisingly we establish inter-reducibility of the expected stopping-time problem for Markov chains with the Positivity problem (which is related to the well-known Skolem problem), for which establishing either decidability or undecidability would be a major breakthrough. Given the hardness of the exact problem, we consider the approximate version of the problem: we show that it can be solved in exponential time for Markov chains and in exponential space for MDPs.
title Stochastic Processes with Expected Stopping Time
topic Logic in Computer Science
url https://arxiv.org/abs/2104.07278