Hierarchical co-clustering with augmented matrices from external domains. - Kai Sugahara; Kazushi Okamoto (Pattern Recognit., 2023)

Is It Really Complementary? Revisiting Behavior-based Labels for Complementary Recommendation. - Kai Sugahara; Chihiro Yamasaki; Kazushi Okamoto (RecSys, 2024)

Hierarchical matrix factorization for interpretable collaborative filtering. - Kai Sugahara; Kazushi Okamoto (Pattern Recognit. Lett., 2024)

Function-based Labels for Complementary Recommendation: Definition, Annotation, and LLM-as-a-Judge. - Chihiro Yamasaki; Kai Sugahara; Yuma Nagi; Kazushi Okamoto (CoRR, 2025)