Prototype-Guided Representation Projection for Multi-Domain Multi-Task Recommendation

Multi-domain and multi-task learning enhance the efficiency and performance of industrial recommendation systems by integrating information from different domains/tasks to model user interests uniformly. However, existing methods suffer from the problem of representation entanglement, which limits the effective handling of commonality and specificity among various domains/tasks. In this paper, we propose a Prototype-guided Representation Projection (PRP) model to address this issue, which explores a novel direction of applying prototype learning to deal with complex domain/task relationships in the recommendation field. To identify inter-domain/task commonality, PRP initially uses a shared Mixture of Experts (MoE) architecture to learn representations for each sample, projecting them into a common prototype space across all domains/tasks. For domain/task specificity, specific feature extraction experts are employed, and sample representations are projected to the corresponding prototype spaces, constrained by an orthogonal loss to ensure the independence of those spaces. Moreover, PRP utilizes Optimal Transport (OT) to guide the correct representation projection within the prototype spaces, employing the linear combination of prototypes as the new sample representation. We conduct offline experiments on two open-source datasets and deploy our approach in an online system for A/B testing. Extensive experimental results consistently demonstrate that our approach outperforms existing methods.