Fast Listwise Passage Reranking via Semantic Tokens

Omkar Prabhune, Xijun Wang, Nan Bi, Haiyan Wang, Shima Alizadeh, Anoop Jain, Yu Lou, Junbang Liang


Abstract
Listwise passage reranking often achieves strong ranking performance, but it incurs substantial computational cost. We propose FLASH, an efficient listwise reranking framework based on semantic token compression and single-step listwise scoring. FLASH represents each query–passage pair with a small set of query-aware semantic tokens and jointly scores all candidates in a single decoder step, enabling query-conditioned joint scoring without expensive token-level listwise processing. We further introduce multi-cardinality training, which allows a single model to support different semantic-token budgets at inference time. We also propose FLASH-LITE, a lightweight variant with offline passage encoding for low-cost online inference. Across TREC and BEIR benchmarks, FLASH improves average ranking effectiveness at comparable online latency and slightly lower FLOPs, while FLASH-Lite substantially reduces query-time cost with a modest effectiveness trade-off. FLASH-LITE enables offline passage encoding, substantially reducing online query-time cost while maintaining competitive reranking performance. Code is provided in the supplementary material.
Anthology ID:
2026.aacl-long.217
Volume:
Proceedings of the 15th International Joint Conference on Natural Language Processing and the 5th Conference of the Asia-Pacific Chapter of the Association for Computational Linguistics (Volume 1: Long Papers)
Month:
November
Year:
2026
Address:
Hengqin, China
Editors:
Yue Zhang, Ruifeng Xu, Ayu Purwarianti, Tong Rong, Jun Suzuki
Venues:
AACL | IJCNLP
SIG:
Publisher:
Association for Computational Linguistics
Note:
Pages:
4897–4910
Language:
URL:
https://aclanthology.org/2026.aacl-long.217/
DOI:
Bibkey:
Cite (ACL):
Omkar Prabhune, Xijun Wang, Nan Bi, Haiyan Wang, Shima Alizadeh, Anoop Jain, Yu Lou, and Junbang Liang. 2026. Fast Listwise Passage Reranking via Semantic Tokens. In Proceedings of the 15th International Joint Conference on Natural Language Processing and the 5th Conference of the Asia-Pacific Chapter of the Association for Computational Linguistics (Volume 1: Long Papers), pages 4897–4910, Hengqin, China. Association for Computational Linguistics.
Cite (Informal):
Fast Listwise Passage Reranking via Semantic Tokens (Prabhune et al., AACL-IJCNLP 2026)
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PDF:
https://aclanthology.org/2026.aacl-long.217.pdf