GInRec: A Gated Architecture for Inductive Recommendation using Knowledge Graphs

We have witnessed increasing interest in exploiting KGs to integrate contextual knowledge in recommender systems in addition to user-item interactions, e.g., ratings. Yet, most methods are transductive, i.e., they represent instances seen during training as low-dimensionality vectors but cannot do so for unseen instances. Hence, they require heavy retraining every time new items or users are added. Conversely, inductive methods promise to solve these issues. KGs enhance inductive recommendation by offering information on item-entity relationships, whereas existing inductive methods rely purely on interactions, which makes recommendations for users with few interactions sub-optimal and even impossible for new items. In this work, we investigate the actual ability of inductive methods exploiting both the structure and the data represented by KGs. Hence, we propose GInRec, a state-of-the-art method that uses a graph neural network with relation-specific gates and a KG to provide better recommendations for new users and items than related inductive methods. As a result, we re-evaluate state-of-the-art methods, identify better evaluation protocols, highlight unwarranted conclusions from previous proposals, and showcase a novel, stronger architecture for this task. The source code is available at: https://github.com/theisjendal/kars2023-recommendation-framework.