LocalSUG: City-Preference-Enhanced LLM for Query Suggestion in Local-Life Services

Jinwen Chen, Shiwen Zhang, Shuai Gong, Zheng Zhang, Yachao Zhao, Lingxiang Wang, Haibo Zhou, Wei Lin, Hainan Zhang


Abstract
In local-life service platforms, query suggestion reduces user effort by generating candidate queries from input prefixes. Traditional multi-stage systems rely heavily on historical popular queries, limiting their ability to capture long-tail and emerging demand. Although LLMs provide strong semantic generalization, their deployment in local-life services faces three challenges: insufficient city-preference awareness, exposure bias in preference optimization, and strict online latency constraints. We propose LocalSUG, an LLM-based query suggestion framework for local-life services. LocalSUG mines city-preference-enhanced candidates from term co-occurrence and injects them into prompts as dynamic references rather than fusing them into model parameters. This allows the model to adapt to changing city preferences, such as merchant openings or closures, while reducing stale or locally invalid suggestions. We further introduce a beam-search-driven GRPO algorithm to align training with inference-time decoding and optimize relevance together with business-oriented rewards. Finally, quality-aware beam acceleration and vocabulary pruning reduce online latency while preserving generation quality. Offline evaluations and large-scale online A/B testing show that LocalSUG improves CTR by +0.35% and reduces the low/no-result rate by 3.98%, demonstrating its effectiveness in real-world deployment.
Anthology ID:
2026.emnlp-industry.14
Volume:
Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing: Industry Track
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Pepa Atanasova, Gholamreza Haffari, Minghan Wang
Venue:
EMNLP
SIG:
SIGDAT
Publisher:
Association for Computational Linguistics
Note:
Pages:
211–224
Language:
URL:
https://aclanthology.org/2026.emnlp-industry.14/
DOI:
Bibkey:
Cite (ACL):
Jinwen Chen, Shiwen Zhang, Shuai Gong, Zheng Zhang, Yachao Zhao, Lingxiang Wang, Haibo Zhou, Wei Lin, and Hainan Zhang. 2026. LocalSUG: City-Preference-Enhanced LLM for Query Suggestion in Local-Life Services. In Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing: Industry Track, pages 211–224, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
LocalSUG: City-Preference-Enhanced LLM for Query Suggestion in Local-Life Services (Chen et al., EMNLP 2026)
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PDF:
https://aclanthology.org/2026.emnlp-industry.14.pdf