FRVA: Fact-Retrieval and Verification Augmented Entailment Tree Generation for Explainable Question Answering

Yue Fan, Hu Zhang, Ru Li, YuJie Wang, Hongye Tan, Jiye Liang


Abstract
Structured entailment tree can exhibit the reasoning chains from knowledge facts to predicted answers, which is important for constructing an explainable question answering system. Existing works mainly include directly generating the entire tree and stepwise generating the proof steps. The stepwise methods can exploit combinatoriality and generalize to longer steps, but they have large fact search spaces and error accumulation problems resulting in the generation of invalid steps. In this paper, inspired by the Dual Process Theory in cognitive science, we propose FRVA, a Fact-Retrieval and Verification Augmented bidirectional entailment tree generation method that contains two systems. Specifically, System 1 makes intuitive judgments through the fact retrieval module and filters irrelevant facts to reduce the search space. System 2 designs a deductive-abductive bidirectional reasoning module, and we construct cross-verification and multi-view contrastive learning to make the generated proof steps closer to the target hypothesis. We enhance the reliability of the stepwise proofs to mitigate error propagation. Experiment results on EntailmentBank show that FRVA outperforms previous models and achieves state-of-the-art performance in fact selection and structural correctness.
Anthology ID:
2024.findings-acl.540
Volume:
Findings of the Association for Computational Linguistics ACL 2024
Month:
August
Year:
2024
Address:
Bangkok, Thailand and virtual meeting
Editors:
Lun-Wei Ku, Andre Martins, Vivek Srikumar
Venue:
Findings
SIG:
Publisher:
Association for Computational Linguistics
Note:
Pages:
9111–9128
Language:
URL:
https://aclanthology.org/2024.findings-acl.540
DOI:
Bibkey:
Cite (ACL):
Yue Fan, Hu Zhang, Ru Li, YuJie Wang, Hongye Tan, and Jiye Liang. 2024. FRVA: Fact-Retrieval and Verification Augmented Entailment Tree Generation for Explainable Question Answering. In Findings of the Association for Computational Linguistics ACL 2024, pages 9111–9128, Bangkok, Thailand and virtual meeting. Association for Computational Linguistics.
Cite (Informal):
FRVA: Fact-Retrieval and Verification Augmented Entailment Tree Generation for Explainable Question Answering (Fan et al., Findings 2024)
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PDF:
https://aclanthology.org/2024.findings-acl.540.pdf