Multiple-policy Evaluation via Density Estimation

Fuente: arXiv
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Autores principales: Chen, Yilei, Pacchiano, Aldo, Paschalidis, Ioannis Ch.
Formato: Preprint
Publicado: 2024
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author Chen, Yilei
Pacchiano, Aldo
Paschalidis, Ioannis Ch.
author_facet Chen, Yilei
Pacchiano, Aldo
Paschalidis, Ioannis Ch.
contents We study the multiple-policy evaluation problem where we are given a set of $K$ policies and the goal is to evaluate their performance (expected total reward over a fixed horizon) to an accuracy $ε$ with probability at least $1-δ$. We propose an algorithm named $\mathrm{CAESAR}$ for this problem. Our approach is based on computing an approximate optimal offline sampling distribution and using the data sampled from it to perform the simultaneous estimation of the policy values. $\mathrm{CAESAR}$ has two phases. In the first we produce coarse estimates of the visitation distributions of the target policies at a low order sample complexity rate that scales with $\tilde{O}(\frac{1}ε)$. In the second phase, we approximate the optimal offline sampling distribution and compute the importance weighting ratios for all target policies by minimizing a step-wise quadratic loss function inspired by the DualDICE \cite{nachum2019dualdice} objective. Up to low order and logarithmic terms $\mathrm{CAESAR}$ achieves a sample complexity $\tilde{O}\left(\frac{H^4}{ε^2}\sum_{h=1}^H\max_{k\in[K]}\sum_{s,a}\frac{(d_h^{π^k}(s,a))^2}{μ^*_h(s,a)}\right)$, where $d^π$ is the visitation distribution of policy $π$, $μ^*$ is the optimal sampling distribution, and $H$ is the horizon.
format Preprint
id arxiv_https___arxiv_org_abs_2404_00195
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Multiple-policy Evaluation via Density Estimation
Chen, Yilei
Pacchiano, Aldo
Paschalidis, Ioannis Ch.
Machine Learning
Artificial Intelligence
We study the multiple-policy evaluation problem where we are given a set of $K$ policies and the goal is to evaluate their performance (expected total reward over a fixed horizon) to an accuracy $ε$ with probability at least $1-δ$. We propose an algorithm named $\mathrm{CAESAR}$ for this problem. Our approach is based on computing an approximate optimal offline sampling distribution and using the data sampled from it to perform the simultaneous estimation of the policy values. $\mathrm{CAESAR}$ has two phases. In the first we produce coarse estimates of the visitation distributions of the target policies at a low order sample complexity rate that scales with $\tilde{O}(\frac{1}ε)$. In the second phase, we approximate the optimal offline sampling distribution and compute the importance weighting ratios for all target policies by minimizing a step-wise quadratic loss function inspired by the DualDICE \cite{nachum2019dualdice} objective. Up to low order and logarithmic terms $\mathrm{CAESAR}$ achieves a sample complexity $\tilde{O}\left(\frac{H^4}{ε^2}\sum_{h=1}^H\max_{k\in[K]}\sum_{s,a}\frac{(d_h^{π^k}(s,a))^2}{μ^*_h(s,a)}\right)$, where $d^π$ is the visitation distribution of policy $π$, $μ^*$ is the optimal sampling distribution, and $H$ is the horizon.
title Multiple-policy Evaluation via Density Estimation
topic Machine Learning
Artificial Intelligence
url https://arxiv.org/abs/2404.00195