Dynamics-Aware Adaptation for Reinforcement Learning Based Cross-Domain Interactive Recommendation

Interactive recommender systems (IRS) have received wide attention in recent years. To capture users' dynamic preferences and maximize their long-term engagement, IRS are usually formulated as reinforcement learning (RL) problems. Despite the promise to solve complex decision-making problems, RL-based methods generally require a large amount of online interaction, restricting their applications due to economic considerations. One possible direction to alleviate this issue is cross-domain recommendation that aims to leverage abundant logged interaction data from a source domain (e.g., adventure genre in movie recommendation) to improve the recommendation quality in the target domain (e.g., crime genre). Nevertheless, prior studies mostly focus on adapting the static representations of users/items. Few have explored how the temporally dynamic user-item interaction patterns transform across domains. Motivated by the above consideration, we propose DACIR, a novelDoubly-Adaptive deep RL-based framework forCross-domain Interactive Recommendation. We first pinpoint how users behave differently in two domains and highlight the potential to leverage the shared user dynamics to boost IRS. To transfer static user preferences across domains, DACIR enforces consistency of item representation by aligning embeddings into a shared latent space. In addition, given the user dynamics in IRS, DACIR calibrates the dynamic interaction patterns in two domains via reward correlation. Once the double adaptation narrows the cross-domain gap, we are able to learn a transferable policy for the target recommender by leveraging logged data. Experiments on real-world datasets validate the superiority of our approach, which consistently achieves significant improvements over the baselines.