CaLM: Contrasting Large and Small Language Models to Verify Grounded Generation

I-Hung Hsu, Zifeng Wang, Long Le, Lesly Miculicich, Nanyun Peng, Chen-Yu Lee, Tomas Pfister


Abstract
Grounded generation aims to equip language models (LMs) with the ability to produce more credible and accountable responses by accurately citing verifiable sources. However, existing methods, by either feeding LMs with raw or preprocessed materials, remain prone to errors. To address this, we introduce CaLM, a novel verification framework. CaLM leverages the insight that a robust grounded response should be consistent with information derived solely from its cited sources. Our framework empowers smaller LMs, which rely less on parametric memory and excel at processing relevant information given a query, to validate the output of larger LMs. Larger LM responses that closely align with the smaller LMs’ output, which relies exclusively on cited documents, are verified. Responses showing discrepancies are iteratively refined through a feedback loop. Experiments on three open-domain question-answering datasets demonstrate significant performance gains of 1.5% to 7% absolute average without any required model fine-tuning.
Anthology ID:
2024.findings-acl.759
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:
12782–12803
Language:
URL:
https://aclanthology.org/2024.findings-acl.759
DOI:
Bibkey:
Cite (ACL):
I-Hung Hsu, Zifeng Wang, Long Le, Lesly Miculicich, Nanyun Peng, Chen-Yu Lee, and Tomas Pfister. 2024. CaLM: Contrasting Large and Small Language Models to Verify Grounded Generation. In Findings of the Association for Computational Linguistics ACL 2024, pages 12782–12803, Bangkok, Thailand and virtual meeting. Association for Computational Linguistics.
Cite (Informal):
CaLM: Contrasting Large and Small Language Models to Verify Grounded Generation (Hsu et al., Findings 2024)
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PDF:
https://aclanthology.org/2024.findings-acl.759.pdf