activity
20232026
most citedOff-Policy Evaluation of Slate Bandit Policies via Optimizing Abstraction

8 citations · 8 across the 10 of their papers we have counts for

collaborators

10 papers

cs.IR2026

Not All Matches Are Equally Valuable: An Online Experiment of Retention-Focused Recommendation in a Job-Matching Platform

Tatsuya Ute, Chiaki Ichimura, Yuta Saito

Recommender systems in two-sided matching platforms are commonly optimized for immediate engagement signals such as click-through rate, reply rate, or the total number of successfu…

cs.LG2026

Combinatorial Allocation Bandits with Nonlinear Arm Utility

Yuki Shibukawa, Koichi Tanaka, Yuta Saito +1

A matching platform is a system that matches participants of different types, such as companies and job-seekers. In such a platform, maximizing matches may concentrate assignments…

cs.LG2026

Beyond Match Maximization and Fairness: Retention-Optimized Two-Sided Matching

Ren Kishimoto, Rikiya Takehi, Koichi Tanaka +4

On two-sided matching platforms such as online dating and recruiting, recommendation algorithms often aim to maximize the total number of matches. However, this objective creates a…

cs.LG2025

A General Framework for Off-Policy Learning with Partially-Observed Reward

Rikiya Takehi, Masahiro Asami, Kosuke Kawakami +1

Off-policy learning (OPL) in contextual bandits aims to learn a decision-making policy that maximizes the target rewards by using only historical interaction data collected under p…

cs.LG2025

Prompt Optimization with Logged Bandit Data

Haruka Kiyohara, Daniel Yiming Cao, Yuta Saito +1

We study how to use naturally available user feedback, such as clicks, to optimize large language model (LLM) pipelines for generating personalized sentences using prompts. Naive a…

stat.ML2024

Effective Off-Policy Evaluation and Learning in Contextual Combinatorial Bandits

Tatsuhiro Shimizu, Koichi Tanaka, Ren Kishimoto +3

We explore off-policy evaluation and learning (OPE/L) in contextual combinatorial bandits (CCB), where a policy selects a subset in the action space. For example, it might choose a…

cs.LG2024

Hyperparameter Optimization Can Even be Harmful in Off-Policy Learning and How to Deal with It

Yuta Saito, Masahiro Nomura

There has been a growing interest in off-policy evaluation in the literature such as recommender systems and personalized medicine. We have so far seen significant progress in deve…

stat.ML2024★ 8 cited

Off-Policy Evaluation of Slate Bandit Policies via Optimizing Abstraction

Haruka Kiyohara, Masahiro Nomura, Yuta Saito

We study off-policy evaluation (OPE) in the problem of slate contextual bandits where a policy selects multi-dimensional actions known as slates. This problem is widespread in reco…

cs.LG2023

Towards Assessing and Benchmarking Risk-Return Tradeoff of Off-Policy Evaluation

Haruka Kiyohara, Ren Kishimoto, Kosuke Kawakami +3

Off-Policy Evaluation (OPE) aims to assess the effectiveness of counterfactual policies using only offline logged data and is often used to identify the top-k promising policies fo…

cs.LG2023

SCOPE-RL: A Python Library for Offline Reinforcement Learning and Off-Policy Evaluation

Haruka Kiyohara, Ren Kishimoto, Kosuke Kawakami +3

This paper introduces SCOPE-RL, a comprehensive open-source Python software designed for offline reinforcement learning (offline RL), off-policy evaluation (OPE), and selection (OP…