ProtoCF: Prototypical Collaborative Filtering for Few-shot Recommendation

In recent times, deep learning methods have supplanted conventional collaborative filtering approaches as the backbone of modern recommender systems. However, their gains are skewed towards popular items with a drastic performance drop for the vast collection of long-tail items with sparse interactions. Moreover, we empirically show that prior neural recommenders lack the resolution power to accurately rank relevant items within the long-tail. In this paper, we formulate long-tail item recommendations as a few-shot learning problem of learning-to-recommend few-shot items with very few interactions. We propose a novel meta-learning framework ProtoCF that learns-to-compose robust prototype representations for few-shot items. ProtoCF utilizes episodic few-shot learning to extract meta-knowledge across a collection of diverse meta-training tasks designed to mimic item ranking within the tail. To further enhance discriminative power, we propose a novel architecture-agnostic technique based on knowledge distillation to extract, relate, and transfer knowledge from neural base recommenders. Our experimental results demonstrate that ProtoCF consistently outperforms state-of-art approaches on overall recommendation (by 5% Recall@50) while achieving significant gains (of 60-80% Recall@50) for tail items with less than 20 interactions.