collaborators

7 papers

cs.LG2026

Offline Contextual Bandits in the Presence of New Actions

Ren Kishimoto, Tatsuhiro Shimizu, Kazuki Kawamura +6

Automated decision-making algorithms drive applications such as recommendation systems and search engines. These algorithms often rely on off-policy contextual bandits or off-polic…

cs.CL2026

PROTEA: Offline Evaluation and Iterative Refinement for Multi-Agent LLM Workflows

Kazuki Kawamura, Satoshi Waki, Kei Tateno

Multi-agent LLM workflows -- systems composed of multiple role-specific LLM calls -- often outperform single-prompt baselines, but they remain difficult to debug and refine. Failur…

cs.LG2026

Off-Policy Evaluation for Ranking Policies under Deterministic Logging Policies

Koichi Tanaka, Kazuki Kawamura, Takanori Muroi +6

Off-Policy Evaluation (OPE) is an important practical problem in algorithmic ranking systems, where the goal is to estimate the expected performance of a new ranking policy using o…

cs.HC2026

LoopLens: Supporting Search as Creation in Loop-Based Music Composition

Sheng Long, Atsuya Kobayashi, Kei Tateno

Creativity support tools (CSTs) typically frame search as information retrieval, yet in practices like electronic dance music production, search serves as a creative medium for col…

cs.AI2025

Safely Exploring Novel Actions in Recommender Systems via Deployment-Efficient Policy Learning

Haruka Kiyohara, Yusuke Narita, Yuta Saito +2

In many real recommender systems, novel items are added frequently over time. The importance of sufficiently presenting novel actions has widely been acknowledged for improving lon…

cs.IR2025

Counterfactual Reciprocal Recommender Systems for User-to-User Matching

Kazuki Kawamura, Takuma Udagawa, Kei Tateno

Reciprocal recommender systems (RRS) in dating, gaming, and talent platforms require mutual acceptance for a match. Logged data, however, over-represents popular profiles due to pa…