Belief Memory: Agent Memory Under Partial Observability

Fuente: arXiv
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Main Authors: Liao, Junfeng, Wang, Qizhou, Zhu, Jianing, Du, Bo, Yan, Rui, Chen, Xiuying
Format: Preprint
Published: 2026
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_version_ 1866909025163018240
author Liao, Junfeng
Wang, Qizhou
Zhu, Jianing
Du, Bo
Yan, Rui
Chen, Xiuying
author_facet Liao, Junfeng
Wang, Qizhou
Zhu, Jianing
Du, Bo
Yan, Rui
Chen, Xiuying
contents LLM agents that operate over long context depend on external memory to accumulate knowledge over time. However, existing methods typically store each observation as a single deterministic conclusion (e.g., inferring "API~X failed" from temporary errors), even though such observations are inherently partial and potentially ambiguous. By committing to one conclusion and discarding uncertainty, these methods introduce self-reinforcing error: the agent acts on the stored conclusion, never revisits alternatives, and reinforces the conclusion over time. To address this issue, we propose BeliefMem, which shifts the memory paradigm from committing to a single conclusion per observation to retaining multiple candidate conclusions with their probabilities. Concretely, BeliefMem stores the candidate conclusions as separate memory entries, each carrying a probability that is updated via Noisy-OR rules as new observations arrive. At retrieval, all candidates surface together with their probabilities, keeping alternatives visible to the agent. Since each conclusion in memory retains its probability, BeliefMem preserves the uncertainty that the deterministic paradigm discards, enabling the agent to act with high confidence on well-evidenced knowledge while retaining the capacity to update its confidence when new evidence arrives. Empirical evaluations on LoCoMo and ALFWorld benchmarks show that, even with limited data, BeliefMem achieves the best average performance, remarkably outperforming well-known baselines. More broadly, such probabilistic memory produces substantial gains and explores a new direction for agent memory in partially observable environments.
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id arxiv_https___arxiv_org_abs_2605_05583
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Belief Memory: Agent Memory Under Partial Observability
Liao, Junfeng
Wang, Qizhou
Zhu, Jianing
Du, Bo
Yan, Rui
Chen, Xiuying
Artificial Intelligence
Computation and Language
LLM agents that operate over long context depend on external memory to accumulate knowledge over time. However, existing methods typically store each observation as a single deterministic conclusion (e.g., inferring "API~X failed" from temporary errors), even though such observations are inherently partial and potentially ambiguous. By committing to one conclusion and discarding uncertainty, these methods introduce self-reinforcing error: the agent acts on the stored conclusion, never revisits alternatives, and reinforces the conclusion over time. To address this issue, we propose BeliefMem, which shifts the memory paradigm from committing to a single conclusion per observation to retaining multiple candidate conclusions with their probabilities. Concretely, BeliefMem stores the candidate conclusions as separate memory entries, each carrying a probability that is updated via Noisy-OR rules as new observations arrive. At retrieval, all candidates surface together with their probabilities, keeping alternatives visible to the agent. Since each conclusion in memory retains its probability, BeliefMem preserves the uncertainty that the deterministic paradigm discards, enabling the agent to act with high confidence on well-evidenced knowledge while retaining the capacity to update its confidence when new evidence arrives. Empirical evaluations on LoCoMo and ALFWorld benchmarks show that, even with limited data, BeliefMem achieves the best average performance, remarkably outperforming well-known baselines. More broadly, such probabilistic memory produces substantial gains and explores a new direction for agent memory in partially observable environments.
title Belief Memory: Agent Memory Under Partial Observability
topic Artificial Intelligence
Computation and Language
url https://arxiv.org/abs/2605.05583