POI Recommendation with LLM-Augmented Multi-Graph Learning and Contrastive Alignment

Point-of-interest (POI) recommendation models based on graph neural networks achieve strong performance by propagating collaborative signals over user-item interactions, yet they struggle with the cold-start problem, where items with few or no interactions are not represented. In this paper, we propose LLM-augmented Multi-Graph Contrastive Learning (LLM-MGCL), a multi-graph neural network that uses semantic and spatial information about items to extend the LightGCN backbone with two auxiliary item-item graphs: a semantic graph constructed from sentence embeddings of LLM-generated photo summaries and keywords, and a geographic graph derived from Haversine distances between business locations. Item embeddings are propagated over all three graphs in parallel, fused additively, and aligned across views through a bidirectional InfoNCE contrastive objective that connects behavioral, semantic, and spatial representations of the same items. Experiments on the Yelp Multimodal Recommendation Dataset show that LLM-MGCL outperforms classical collaborative filtering, matrix factorization, and non-contrastive graph neural network baselines. It improves Recall@20 by 48.5% and NDCG@20 by 59.0% over LightGCN, while trailing the strongest contrastive baseline, Self-supervised Graph Learning (SGL), slightly in aggregate. A popularity-stratified evaluation shows that LLM-MGCL achieves the highest recall on cold and warm items, whereas SGL remains better on popular items. An ablation study reveals that the cross-view contrastive alignment (CA) is the primary driver of the aggregate gains. Our results suggest that externally grounded, LLM-derived item knowledge can partially compensate for missing collaborative signal and mitigate the item cold-start problem in POI recommendation.