ThinkQE: Query Expansion via an Evolving Thinking Process

Yibin Lei, Tao Shen, Andrew Yates


Abstract
Effective query expansion for web search benefits from promoting both exploration and result diversity to capture multiple interpretations and facets of a query. While recent LLM-based methods have improved retrieval performance and demonstrate strong domain generalization without additional training, they often generate narrowly focused expansions that overlook these desiderata. We propose ThinkQE, a test-time query expansion framework addressing this limitation through two key components: a thinking-based expansion process that encourages deeper and comprehensive semantic exploration, and a corpus-interaction strategy that iteratively refines expansions using retrieval feedback from the corpus. Experiments on diverse web search benchmarks (DL19, DL20, and BRIGHT) show ThinkQE consistently outperforms prior approaches, including training-intensive dense retrievers and rerankers.
Anthology ID:
2025.findings-emnlp.965
Volume:
Findings of the Association for Computational Linguistics: EMNLP 2025
Month:
November
Year:
2025
Address:
Suzhou, China
Editors:
Christos Christodoulopoulos, Tanmoy Chakraborty, Carolyn Rose, Violet Peng
Venue:
Findings
SIG:
Publisher:
Association for Computational Linguistics
Note:
Pages:
17772–17781
Language:
URL:
https://preview.aclanthology.org/author-page-yu-wang-polytechnic/2025.findings-emnlp.965/
DOI:
10.18653/v1/2025.findings-emnlp.965
Bibkey:
Cite (ACL):
Yibin Lei, Tao Shen, and Andrew Yates. 2025. ThinkQE: Query Expansion via an Evolving Thinking Process. In Findings of the Association for Computational Linguistics: EMNLP 2025, pages 17772–17781, Suzhou, China. Association for Computational Linguistics.
Cite (Informal):
ThinkQE: Query Expansion via an Evolving Thinking Process (Lei et al., Findings 2025)
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PDF:
https://preview.aclanthology.org/author-page-yu-wang-polytechnic/2025.findings-emnlp.965.pdf
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