When Graphs Whisper: Graph Structure Serialization for Embedding Alignment in Cold-Start Recommendation

Yujing Zhang, Huachi Zhou, Ruochen Liu, Qinggang Zhang, Luyao Zhuang, Hao Chen, Zijin Hong, Chang Yang, Xiao Huang


Abstract
Cold-start item recommendation remains challenging as new items lack interaction signals beyond textual descriptions. Existing methods either fine-tune large language models (LLMs) on descriptions or map item content into collaborative spaces learned from user-warm item interactions. However, text-only prompts struggle to capture higher-order graph structures, while distributional differences between behavior and content embeddings weaken alignment based solely on predicted probabilities. To address these issues, we propose Graph Structure Serialization for Embedding Alignment (GraphSEA), an LLM-based framework inspired by the observation that graphs contain sequential structures similar to language and can be serialized as inputs for LLMs. GraphSEA first serializes interaction graphs into structured token sequences for an LLM to learn behavior embeddings that encode collaborative patterns, while the LLM separately generates content embeddings from item descriptions. An embedding alignment module then aligns behavior and content embeddings across multiple facets, including interaction probability, preference order, and item distinction. Extensive experiments demonstrate that GraphSEA improves recommendation performance across warm and cold recommendation tasks, while achieving higher efficiency than LLM-based methods.
Anthology ID:
2026.emnlp-main.1470
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
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Pages:
33642–33660
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URL:
https://aclanthology.org/2026.emnlp-main.1470/
DOI:
Bibkey:
Cite (ACL):
Yujing Zhang, Huachi Zhou, Ruochen Liu, Qinggang Zhang, Luyao Zhuang, Hao Chen, Zijin Hong, Chang Yang, and Xiao Huang. 2026. When Graphs Whisper: Graph Structure Serialization for Embedding Alignment in Cold-Start Recommendation. In Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing, pages 33642–33660, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
When Graphs Whisper: Graph Structure Serialization for Embedding Alignment in Cold-Start Recommendation (Zhang et al., EMNLP 2026)
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PDF:
https://aclanthology.org/2026.emnlp-main.1470.pdf