LOHRec: Leveraging Order and Hierarchy in Generative Sequential Recommendation

Jiawen Xie, Haiyang Wu, Deyi Ji, Yuekui Yang, Shaoping Ma


Abstract
The sequential recommendation task involves predicting the items users will be interested in next based on their past interaction sequence. Recently, sequential recommender systems with generative retrieval have garnered significant attention. However, during training, these generative recommenders focus only on maximizing the prediction probability of the next target item in the temporal sequence, while neglecting awareness of diverse plausible potential items.Although introducing large language models (LLMs) with world knowledge and adding a set of auxiliary tasks that can link item identifiers to their real-world meanings can alleviate this issue, the high inference costs associated with these LLM-based recommenders make them challenging to deploy in practical scenarios. In this paper, we propose a novel learning framework, LOHRec, which leverages the order and hierarchy in generative recommendation using quantized identifiers to further explore the performance ceiling of lightweight generative recommenders. Under fair comparisons with approximate backbone parameter sizes, comprehensive experiments show that all variants of generative recommenders using our framework outperform strong prior baselines across multiple datasets. Furthermore, we empirically demonstrate that LOHRec can efficiently align lightweight generative recommenders with LLM recommendation preferences in low-resource scenarios, further demonstrating its practical utility. Our code repository is available at [https://github.com/xjw-nlp/LOHRec](https://github.com/xjw-nlp/LOHRec).
Anthology ID:
2025.findings-emnlp.977
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:
17968–17983
Language:
URL:
https://aclanthology.org/2025.findings-emnlp.977/
DOI:
Bibkey:
Cite (ACL):
Jiawen Xie, Haiyang Wu, Deyi Ji, Yuekui Yang, and Shaoping Ma. 2025. LOHRec: Leveraging Order and Hierarchy in Generative Sequential Recommendation. In Findings of the Association for Computational Linguistics: EMNLP 2025, pages 17968–17983, Suzhou, China. Association for Computational Linguistics.
Cite (Informal):
LOHRec: Leveraging Order and Hierarchy in Generative Sequential Recommendation (Xie et al., Findings 2025)
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https://aclanthology.org/2025.findings-emnlp.977.pdf
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