Multimodal Optimal Transport Knowledge Distillation for Cross-domain Recommendation

Recommendation systems have been widely used in e-commerce, news media, and short video platforms. With the abundance of images, text, and audio information, users often engage in personalized interactions based on their multimodal preferences. With the continuous expansion of application scenarios, cross domain recommendation issues have become important, such as recommendations in both the public and private domains of e-commerce. The current cross domain recommendation methods have achieved certain results through methods such as shared encoders and contrastive learning. However, fewstudies have focused on the effective extraction and utilization of multimodal information in cross domain recommendations. Furthermore, due to the existence of distribution drift issues, directly constructing feature alignment between source domain and target domain representations is not an effective way. Therefore, we propose a Multimodal Optimal Transport Knowledge Distillation (MOTKD) method for cross domain recommendation. Specifically, we propose a multimodal graph attention network to model the multimodal preference representation of users. Then, we introduce a proxy distribution space as a bridge between the source and target domains. Based on the common proxy distribution, we utilize the optimal transport method to achieve cross domain knowledge transfer. Further, in order to improve the auxiliary training effect of source domain supervised signals on target domain, we design a multi-level cross domain knowledge distillation module. We conducted extensive experiments on two pairs of cross domain datasets composed of four datasets. The experimental results indicate that our proposed MOTKD method outperforms other state-of-the-art models.