Neuro-Symbolic Reasoning with External Inference Tools Mitigates Bias from Sub-Formula Level Logical Structure

Ryo Hasegawa, Yusuke Sakai, Hidetaka Kamigaito, Taro Watanabe


Abstract
Logical reasoning is a core ability of modern language models, and various approaches have been proposed to enhance it. One effective method is neuro-symbolic approach, which makes a model output logic formulas and predict the answer based on them. However, fair comparison is challenging because existing methods use different experimental settings, such as post-processing and prompt styles. In addition, existing error analyses are too coarse to capture the impact of sub-formula level structures. In this paper, we present a systematic analysis of neuro-symbolic approaches under a unified setting with sub-formula level annotation. We reveal that some sub-formula level structures bias the model’s inference toward assuming the answer is true, and neuro-symbolic approaches with an external inference tool help mitigate this bias. On the other hand, these methods sometimes lack flexibility in representing sentence meaning as logic formulas.
Anthology ID:
2026.emnlp-main.2564
Volume:
Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Hung-Yi Lee, Sunipa Dev, Jessy Li, Desmond Elliott
Venue:
EMNLP
SIG:
SIGDAT
Publisher:
Association for Computational Linguistics
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Pages:
58262–58284
Language:
URL:
https://aclanthology.org/2026.emnlp-main.2564/
DOI:
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Cite (ACL):
Ryo Hasegawa, Yusuke Sakai, Hidetaka Kamigaito, and Taro Watanabe. 2026. Neuro-Symbolic Reasoning with External Inference Tools Mitigates Bias from Sub-Formula Level Logical Structure. In Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing, pages 58262–58284, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
Neuro-Symbolic Reasoning with External Inference Tools Mitigates Bias from Sub-Formula Level Logical Structure (Hasegawa et al., EMNLP 2026)
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https://aclanthology.org/2026.emnlp-main.2564.pdf