Mem-LM: An LM-style Model for Reinforced Memory Selection

Yanhan Huang, Yihao Zhong, Wenwen Ouyang, Xing Tian, Zining Yin, Yiyi Lu


Abstract
External memory banks can improve test-time reasoning in frozen large language models without updating backbone parameters. Yet similarity-based retrievers and pointwise selectors score memories independently, ignoring interactions and presentation order. We introduce , an LM-style model for reinforced memory selection that casts context construction as autoregressive index decoding. From a densely retrieved candidate pool, a lightweight Transformer encoder–decoder generates an ordered index sequence [i1,…,ik], modeling dependencies among memories while leaving the backbone frozen. This formulation supports standard language-model training. For sparse binary verifiable rewards, we further propose , a confidence-aware extension of group-relative policy optimization that promotes correct, low-confidence rollouts, penalizes confidently incorrect ones, and retains learning signals in reward-homogeneous groups. Across three mathematical reasoning and two reasoning-intensive question-answering benchmarks with three Qwen backbones,  achieves an average score of 84.9 on Qwen-plus, exceeding the strongest memory-augmented baseline by 2.3 points.
Anthology ID:
2026.emnlp-industry.136
Volume:
Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing: Industry Track
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Pepa Atanasova, Gholamreza Haffari, Minghan Wang
Venue:
EMNLP
SIG:
SIGDAT
Publisher:
Association for Computational Linguistics
Note:
Pages:
2290–2301
Language:
URL:
https://aclanthology.org/2026.emnlp-industry.136/
DOI:
Bibkey:
Cite (ACL):
Yanhan Huang, Yihao Zhong, Wenwen Ouyang, Xing Tian, Zining Yin, and Yiyi Lu. 2026. Mem-LM: An LM-style Model for Reinforced Memory Selection. In Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing: Industry Track, pages 2290–2301, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
Mem-LM: An LM-style Model for Reinforced Memory Selection (Huang et al., EMNLP 2026)
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PDF:
https://aclanthology.org/2026.emnlp-industry.136.pdf