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Pointwise Mutual Information Based Metric and Decoding Strategy for Faithful Generation in Document Grounded Dialogs

Yatin Nandwani, Vineet Kumar, Dinesh Raghu, Sachindra Joshi, Luis Lastras


Abstract
A major concern in using deep learning based generative models for document-grounded dialogs is the potential generation of responses that are not faithful to the underlying document. Existing automated metrics used for evaluating the faithfulness of response with respect to the grounding document measure the degree of similarity between the generated response and the document’s content. However, these automated metrics are far from being well aligned with human judgments. Therefore, to improve the measurement of faithfulness, we propose a new metric that utilizes (Conditional) Point-wise Mutual Information (PMI) between the generated response and the source document, conditioned on the dialogue. PMI quantifies the extent to which the document influences the generated response – with a higher PMI indicating a more faithful response. We build upon this idea to create a new decoding technique that incorporates PMI into the response generation process to predict more faithful responses. Our experiments on the BEGIN benchmark demonstrate an improved correlation of our metric with human evaluation. We also show that our decoding technique is effective in generating more faithful responses when compared to standard decoding techniques on a set of publicly available document-grounded dialog datasets.
Anthology ID:
2023.emnlp-main.639
Volume:
Proceedings of the 2023 Conference on Empirical Methods in Natural Language Processing
Month:
December
Year:
2023
Address:
Singapore
Editors:
Houda Bouamor, Juan Pino, Kalika Bali
Venue:
EMNLP
SIG:
Publisher:
Association for Computational Linguistics
Note:
Pages:
10335–10347
Language:
URL:
https://aclanthology.org/2023.emnlp-main.639
DOI:
10.18653/v1/2023.emnlp-main.639
Bibkey:
Cite (ACL):
Yatin Nandwani, Vineet Kumar, Dinesh Raghu, Sachindra Joshi, and Luis Lastras. 2023. Pointwise Mutual Information Based Metric and Decoding Strategy for Faithful Generation in Document Grounded Dialogs. In Proceedings of the 2023 Conference on Empirical Methods in Natural Language Processing, pages 10335–10347, Singapore. Association for Computational Linguistics.
Cite (Informal):
Pointwise Mutual Information Based Metric and Decoding Strategy for Faithful Generation in Document Grounded Dialogs (Nandwani et al., EMNLP 2023)
Copy Citation:
PDF:
https://aclanthology.org/2023.emnlp-main.639.pdf
Video:
 https://aclanthology.org/2023.emnlp-main.639.mp4