Search Results for author: Kenshi Abe

Found 19 papers, 7 papers with code

Filtered Direct Preference Optimization

1 code implementation22 Apr 2024 Tetsuro Morimura, Mitsuki Sakamoto, Yuu Jinnai, Kenshi Abe, Kaito Ariu

This paper addresses the issue of text quality within the preference dataset by focusing on Direct Preference Optimization (DPO), an increasingly adopted reward-model-free RLHF method.

Regularized Best-of-N Sampling to Mitigate Reward Hacking for Language Model Alignment

1 code implementation1 Apr 2024 Yuu Jinnai, Tetsuro Morimura, Kaito Ariu, Kenshi Abe

Best-of-N (BoN) sampling with a reward model has been shown to be an effective strategy for aligning Large Language Models (LLMs) to human preferences at the time of decoding.

Language Modelling

Scalable and Provably Fair Exposure Control for Large-Scale Recommender Systems

1 code implementation22 Feb 2024 Riku Togashi, Kenshi Abe, Yuta Saito

Typical recommendation and ranking methods aim to optimize the satisfaction of users, but they are often oblivious to their impact on the items (e. g., products, jobs, news, video) and their providers.

Collaborative Filtering Exposure Fairness +1

Return-Aligned Decision Transformer

no code implementations6 Feb 2024 Tsunehiko Tanaka, Kenshi Abe, Kaito Ariu, Tetsuro Morimura, Edgar Simo-Serra

Traditional approaches in offline reinforcement learning aim to learn the optimal policy that maximizes the cumulative reward, also known as return.

Learning Fair Division from Bandit Feedback

no code implementations15 Nov 2023 Hakuei Yamada, Junpei Komiyama, Kenshi Abe, Atsushi Iwasaki

This work addresses learning online fair division under uncertainty, where a central planner sequentially allocates items without precise knowledge of agents' values or utilities.

Model-Based Minimum Bayes Risk Decoding

no code implementations9 Nov 2023 Yuu Jinnai, Tetsuro Morimura, Ukyo Honda, Kaito Ariu, Kenshi Abe

MBR decoding selects a hypothesis from a pool of hypotheses that has the least expected risk under a probability model according to a given utility function.

Text Generation

Slingshot Perturbation to Learning in Monotone Games

no code implementations26 May 2023 Kenshi Abe, Kaito Ariu, Mitsuki Sakamoto, Atsushi Iwasaki

This paper addresses the problem of learning Nash equilibria in {\it monotone games} where the gradient of the payoff functions is monotone in the strategy profile space, potentially containing additive noise.

Exploration of Unranked Items in Safe Online Learning to Re-Rank

no code implementations2 May 2023 Hiroaki Shiino, Kaito Ariu, Kenshi Abe, Togashi Riku

In this paper, we propose a safe OLTR algorithm that efficiently exchanges one of the items in the current ranking with an item outside the ranking (i. e., an unranked item) to perform exploration.

Learning-To-Rank Safe Exploration

Fair Matrix Factorisation for Large-Scale Recommender Systems

no code implementations9 Sep 2022 Riku Togashi, Kenshi Abe

However, the intrinsic nature of fairness destroys the separability of optimisation subproblems for users and items, which is an essential property of conventional scalable algorithms, such as implicit alternating least squares (iALS).

Collaborative Filtering Fairness +1

Last-Iterate Convergence with Full and Noisy Feedback in Two-Player Zero-Sum Games

1 code implementation21 Aug 2022 Kenshi Abe, Kaito Ariu, Mitsuki Sakamoto, Kentaro Toyoshima, Atsushi Iwasaki

This paper proposes Mutation-Driven Multiplicative Weights Update (M2WU) for learning an equilibrium in two-player zero-sum normal-form games and proves that it exhibits the last-iterate convergence property in both full and noisy feedback settings.

Multi-agent Reinforcement Learning

Mutation-Driven Follow the Regularized Leader for Last-Iterate Convergence in Zero-Sum Games

1 code implementation18 Jun 2022 Kenshi Abe, Mitsuki Sakamoto, Atsushi Iwasaki

In this study, we consider a variant of the Follow the Regularized Leader (FTRL) dynamics in two-player zero-sum games.

Policy Gradient Algorithms with Monte-Carlo Tree Search for Non-Markov Decision Processes

no code implementations2 Jun 2022 Tetsuro Morimura, Kazuhiro Ota, Kenshi Abe, Peinan Zhang

However, since the standard MCTS does not have the ability to learn state representation, the size of the tree-search space can be too large to search.

Reinforcement Learning (RL)

Anytime Capacity Expansion in Medical Residency Match by Monte Carlo Tree Search

1 code implementation14 Feb 2022 Kenshi Abe, Junpei Komiyama, Atsushi Iwasaki

Constructing a good search tree representation significantly boosts the performance of the proposed method.

Thresholded Lasso Bandit

1 code implementation22 Oct 2020 Kaito Ariu, Kenshi Abe, Alexandre Proutière

In this paper, we revisit the regret minimization problem in sparse stochastic contextual linear bandits, where feature vectors may be of large dimension $d$, but where the reward function depends on a few, say $s_0\ll d$, of these features only.

Mean-Variance Efficient Reinforcement Learning by Expected Quadratic Utility Maximization

no code implementations3 Oct 2020 Masahiro Kato, Kei Nakagawa, Kenshi Abe, Tetsuro Morimura

To achieve this purpose, we train an agent to maximize the expected quadratic utility function, a common objective of risk management in finance and economics.

Decision Making Decision Making Under Uncertainty +3

Off-Policy Exploitability-Evaluation in Two-Player Zero-Sum Markov Games

no code implementations4 Jul 2020 Kenshi Abe, Yusuke Kaneko

The proposed estimators project exploitability that is often used as a metric for determining how close a policy profile (i. e., a tuple of policies) is to a Nash equilibrium in two-player zero-sum games.

Off-policy evaluation Vocal Bursts Valence Prediction

A Simple Heuristic for Bayesian Optimization with A Low Budget

no code implementations18 Nov 2019 Masahiro Nomura, Kenshi Abe

The aim of black-box optimization is to optimize an objective function within the constraints of a given evaluation budget.

Bayesian Optimization Hyperparameter Optimization

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