Off-policy evaluation for episodic partially observable markov decision processes under non-parametric models
We study the problem of off-policy evaluation (OPE) for episodic Partially Observable
Markov Decision Processes (POMDPs) with continuous states. Motivated by the recently
proposed proximal causal inference framework, we develop a non-parametric identification
result for estimating the policy value via a sequence of so-called V-bridge functions with the
help of time-dependent proxy variables. We then develop a fitted-Q-evaluation-type
algorithm to estimate V-bridge functions recursively, where a non-parametric instrumental …
Markov Decision Processes (POMDPs) with continuous states. Motivated by the recently
proposed proximal causal inference framework, we develop a non-parametric identification
result for estimating the policy value via a sequence of so-called V-bridge functions with the
help of time-dependent proxy variables. We then develop a fitted-Q-evaluation-type
algorithm to estimate V-bridge functions recursively, where a non-parametric instrumental …
Abstract
We study the problem of off-policy evaluation (OPE) for episodic Partially Observable Markov Decision Processes (POMDPs) with continuous states. Motivated by the recently proposed proximal causal inference framework, we develop a non-parametric identification result for estimating the policy value via a sequence of so-called V-bridge functions with the help of time-dependent proxy variables. We then develop a fitted-Q-evaluation-type algorithm to estimate V-bridge functions recursively, where a non-parametric instrumental variable (NPIV) problem is solved at each step. By analyzing this challenging sequential NPIV estimation, we establish the finite-sample error bounds for estimating the V-bridge functions and accordingly that for evaluating the policy value, in terms of the sample size, length of horizon and so-called (local) measure of ill-posedness at each step. To the best of our knowledge, this is the first finite-sample error bound for OPE in POMDPs under non-parametric models.
proceedings.neurips.cc