GraphLoRA: Structure-Aware Low-Rank Adaptation for Large Language Model Recommendation
Paper · 2026 · Lin Mu, Guoji Wang, Li Ni et al.
Summary
LLM-based recommenders have trouble combining a language model's textual knowledge with collaborative signals from user–item interactions, which are naturally graph-shaped. Earlier approaches either turn interaction histories into prompt text or soft tokens (TALLRec, CoLLM), or insert fixed, externally trained embeddings into adapter weights (CoRA). In both cases the structural information stays static, and multi-hop relations are lost. GraphLoRA instead places a trainable message-passing GNN inside the LoRA bottleneck, between matrices A and B. Collaborative embeddings, initialized from matrix factorization, are projected into the rank-r space. There they are aggregated over neighbours in the user–item bipartite graph, then mapped back into the model through B. The graph encoder and the LoRA adapter are trained together under the recommendation objective. Experiments on ML-1M, Amazon-Book and Book-Crossing, using Vicuna and LLaMA-7B backbones, show that it outperforms state-of-the-art LLM recommenders with only marginal extra cost. The work suggests that graph reasoning can be built into the adaptation parameters themselves, which gives a cheap path to structure-aware fine-tuning.
Key points
- Core idea: the method extends LoRA from independent low-rank updates to "structure-aware low-rank propagation." The graph module operates in the small rank-r space rather than at d_model width.
- Efficiency: relative to a LoRA-only baseline with trainable MF, GraphLoRA uses 1.017× the parameters and adds roughly 1% latency. CoRA-MF needs 7.635× the parameters, and injecting the signal before A (Pre-A) costs 5.224×.
- Ablations: freezing the MF embeddings gives the weakest results, making them trainable helps, and adding graph aggregation helps most. Among GCN, LightGCN and NGCF encoders, NGCF performs best.
- Injection depth: placing the GNN in deeper Transformer layers works better. The best results come from layer 31 on ML-1M and layer 15 on Amazon-Book.
- Few-shot results: on Book-Crossing with LLaMA-7B under the TALLRec protocol, GraphLoRA reaches AUC 60.90, 61.08 and 67.90 with 16, 64 and 256 training samples. TALLRec scores 56.36, 60.39 and 64.38 on the same settings. Code is available at github.com/wgj15965/GraphLoRA.
Institutions
Fields, topics and concepts
📚 Shelves 3The field of science this work belongs to (OpenAlex fields).Computer Science · 16,667 worksArtificial Intelligence · 16,194 worksInformation Systems · 1,437 works
🧭 Topics 2Research subjects and languages the work is about.Language models & pretraining · 3,320 worksEfficient models & compression · 242 works
Cite
Cite as Lin Mu, Guoji Wang, Li Ni, Lei Sang, Zhize Wu, Peiquan Jin and Yiwen Zhang. 2026. GraphLoRA: Structure-Aware Low-Rank Adaptation for Large Language Model Recommendation. Findings of the Association for Computational Linguistics: ACL 2026.
@inproceedings{mu2026graphlora,
title = {{GraphLoRA: Structure-Aware Low-Rank Adaptation for Large Language Model Recommendation}},
author = {Lin Mu, Guoji Wang, Li Ni, Lei Sang, Zhize Wu, Peiquan Jin and Yiwen Zhang},
booktitle = {Findings of the Association for Computational Linguistics: ACL 2026},
year = {2026},
doi = {10.18653/v1/2026.findings-acl.645},
url = {https://doi.org/10.18653/v1/2026.findings-acl.645}
}References
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