Breaking isolation: Multimodal graph fusion for multimedia recommendation by edge-wise modulation

In a multimedia recommender system, rich multimodal dynamics of user-item interactions are worth availing ourselves of and have been facilitated by Graph Convolutional Networks (GCNs). Yet, the typical way of conducting multimodal fusion with GCN-based models is either through graph mergence fusion that delivers insufficient inter-modal dynamics, or through node alignment fusion that brings in noises which potentially harm multimodal modelling. Unlike existing works, we propose EgoGCN, a structure that seeks to enhance multimodal learning of user-item interactions. At its core is a simple yet effective fusion operation dubbed EdGe-wise mOdulation (EGO) fusion. EGO fusion adaptively distils edge-wise multimodal information and learns to modulate each unimodal node under the supervision of other modalities. It breaks isolated unimodal propagations, allows the most informative inter-modal messages to spread, whilst preserving intra-modal processing. We present a hard modulation and a soft modulation to fully investigate the multimodal dynamics behind. Experiments on two real-world datasets show that EgoGCN comfortably beats prior methods.