Memoryless Policy Iteration for Episodic POMDPs

Roy van Zuijlen; Duarte Antunes

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arXiv · 2512.11082

Memoryless Policy Iteration for Episodic POMDPs

Roy van Zuijlen·Duarte Antunes

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Abstract

Memoryless and finite-memory policies offer a practical alternative for solving partially observable Markov decision processes (POMDPs), as they operate directly in the output space rather than in the high-dimensional belief space. However, extending classical methods such as policy iteration to this setting remains difficult; the output process is non-Markovian, making policy-improvement steps interdependent across stages. We introduce a new family of monotonically improving policy-iteration algorithms that alternate between single-stage output-based policy improvements and policy evaluations according to a prescribed periodic pattern. We show that this family admits optimal patterns that maximize a natural computational-efficiency index, and we identify the simplest pattern with minimal period. Building on this structure, we further develop a model-free variant that estimates values from data and learns memoryless policies directly. Across several POMDPs examples, our method achieves significant computational speedups over policy-gradient baselines and recent specialized algorithms in both model-based and model-free settings.

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BibTeX RIS

Roy van Zuijlen, Duarte Antunes. 2025-12-11. Memoryless Policy Iteration for Episodic POMDPs. https://arxiv.org/abs/2512.11082

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