Illuminating the Path: Reachability-Aware Supervision Curation for LLM-Based Recommendation

Donghee Han, Jiwon Jeong, Hwanjun Song, Mun Yong Yi


Abstract
Eliciting high-quality reasoning trajectories to supervise Large Language Models (LLMs) in sequential recommendation is notoriously difficult. In massive item pools, standard data curation methods such as autonomous exploration or rejection sampling suffer from severe sparsity. LLMs’ context-utilization bias exacerbate this challenge by overusing noisy interaction histories, yielding diffuse and weakly grounded reasoning paths that frequently fail to retrieve the target item. To overcome this data curation bottleneck, we propose GEARec (Grounded Reasoning Curation for Anchor-based Recommendation), a framework based on Dual-Perspective Anchor Extraction and Hybrid Reasoning Generation. By combining the semantic strengths of LLMs with collaborative filtering (CF) signals, GEARec identifies a high-relevance anchor item from the user’s history to construct highly focused, reachability-aware reasoning trajectories for supervised fine-tuning. Experiments on multiple datasets demonstrate that GEARec effectively curates superior supervision signals, reducing context overuse and consistently outperforming strong baselines in recommendation accuracy.
Anthology ID:
2026.emnlp-main.552
Volume:
Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Hung-Yi Lee, Sunipa Dev, Jessy Li, Desmond Elliott
Venue:
EMNLP
SIG:
SIGDAT
Publisher:
Association for Computational Linguistics
Note:
Pages:
12665–12686
Language:
URL:
https://aclanthology.org/2026.emnlp-main.552/
DOI:
Bibkey:
Cite (ACL):
Donghee Han, Jiwon Jeong, Hwanjun Song, and Mun Yong Yi. 2026. Illuminating the Path: Reachability-Aware Supervision Curation for LLM-Based Recommendation. In Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing, pages 12665–12686, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
Illuminating the Path: Reachability-Aware Supervision Curation for LLM-Based Recommendation (Han et al., EMNLP 2026)
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PDF:
https://aclanthology.org/2026.emnlp-main.552.pdf