Reinforced Internal-External Knowledge Synergistic Reasoning for Efficient Adaptive Search Agent

Ziyang Huang, Xiaowei Yuan, Yiming Ju, Haoran Cai, Jun Zhao, Kang Liu


Abstract
Retrieval-augmented generation (RAG) is a common strategy to reduce hallucinations in Large Language Models (LLMs). While reinforcement learning (RL) can enable LLMs to act as search agents by activating retrieval capabilities, existing ones often underutilize their internal knowledge. This might lead to redundant retrievals, potential harmful knowledge conflicts, and increased inference latency. To address these limitations, an efficient adaptive search agent capable of discerning optimal retrieval timing and synergistically integrating parametric (internal) and retrieved (external) knowledge is in urgent need. This paper introduces the Reinforced Internal-External Knowledge Synergistic REasoning Agent (IKEA), which could indentify its own knowledge boundary and prioritize the utilization of internal knowledge, resorting to external search only when internal knowledge is deemed insufficient. This is achieved using a novel knowledge-boundary aware reward function and a knowledge-boundary aware training dataset. These are designed for internal-external knowledge synergy oriented RL, incentivizing the model to deliver accurate answers, minimize unnecessary retrievals, and encourage appropriate retrievals only when its own knowledge is lacking. Evaluations across multiple knowledge-intensive reasoning tasks demonstrate that IKEA significantly outperforms baseline methods, reduces retrieval frequency significantly, and exhibits robust generalization capabilities.
Anthology ID:
2026.findings-emnlp.2184
Volume:
Findings of the Association for Computational Linguistics: EMNLP 2026
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Hung-Yi Lee, Sunipa Dev, Jessy Li, Desmond Elliott
Venue:
Findings
SIG:
SIGDAT
Publisher:
Association for Computational Linguistics
Note:
Pages:
46768–46785
Language:
URL:
https://aclanthology.org/2026.findings-emnlp.2184/
DOI:
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Cite (ACL):
Ziyang Huang, Xiaowei Yuan, Yiming Ju, Haoran Cai, Jun Zhao, and Kang Liu. 2026. Reinforced Internal-External Knowledge Synergistic Reasoning for Efficient Adaptive Search Agent. In Findings of the Association for Computational Linguistics: EMNLP 2026, pages 46768–46785, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
Reinforced Internal-External Knowledge Synergistic Reasoning for Efficient Adaptive Search Agent (Huang et al., Findings 2026)
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PDF:
https://aclanthology.org/2026.findings-emnlp.2184.pdf