GLEN: Generative Retrieval via Lexical Index Learning

Sunkyung Lee, Minjin Choi, Jongwuk Lee


Abstract
Generative retrieval shed light on a new paradigm of document retrieval, aiming to directly generate the identifier of a relevant document for a query. While it takes advantage of bypassing the construction of auxiliary index structures, existing studies face two significant challenges: (i) the discrepancy between the knowledge of pre-trained language models and identifiers and (ii) the gap between training and inference that poses difficulty in learning to rank. To overcome these challenges, we propose a novel generative retrieval method, namely Generative retrieval via LExical iNdex learning (GLEN). For training, GLEN effectively exploits a dynamic lexical identifier using a two-phase index learning strategy, enabling it to learn meaningful lexical identifiers and relevance signals between queries and documents. For inference, GLEN utilizes collision-free inference, using identifier weights to rank documents without additional overhead. Experimental results prove that GLEN achieves state-of-the-art or competitive performance against existing generative retrieval methods on various benchmark datasets, e.g., NQ320k, MS MARCO, and BEIR. The code is available at https://github.com/skleee/GLEN.
Anthology ID:
2023.emnlp-main.477
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:
7693–7704
Language:
URL:
https://aclanthology.org/2023.emnlp-main.477
DOI:
10.18653/v1/2023.emnlp-main.477
Bibkey:
Cite (ACL):
Sunkyung Lee, Minjin Choi, and Jongwuk Lee. 2023. GLEN: Generative Retrieval via Lexical Index Learning. In Proceedings of the 2023 Conference on Empirical Methods in Natural Language Processing, pages 7693–7704, Singapore. Association for Computational Linguistics.
Cite (Informal):
GLEN: Generative Retrieval via Lexical Index Learning (Lee et al., EMNLP 2023)
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https://aclanthology.org/2023.emnlp-main.477.pdf
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