Search Results for author: Kei Takemura

Found 7 papers, 0 papers with code

Best-of-Three-Worlds Linear Bandit Algorithm with Variance-Adaptive Regret Bounds

no code implementations24 Feb 2023 Shinji Ito, Kei Takemura

At the higher level, the proposed algorithm adapts to a variety of types of environments.

Online Task Assignment Problems with Reusable Resources

no code implementations15 Mar 2022 Hanna Sumita, Shinji Ito, Kei Takemura, Daisuke Hatano, Takuro Fukunaga, Naonori Kakimura, Ken-ichi Kawarabayashi

The key features of our problem are (1) an agent is reusable, i. e., an agent comes back to the market after completing the assigned task, (2) an agent may reject the assigned task to stay the market, and (3) a task may accommodate multiple agents.

Task 2

Near-Optimal Regret Bounds for Contextual Combinatorial Semi-Bandits with Linear Payoff Functions

no code implementations20 Jan 2021 Kei Takemura, Shinji Ito, Daisuke Hatano, Hanna Sumita, Takuro Fukunaga, Naonori Kakimura, Ken-ichi Kawarabayashi

However, there is a gap of $\tilde{O}(\max(\sqrt{d}, \sqrt{k}))$ between the current best upper and lower bounds, where $d$ is the dimension of the feature vectors, $k$ is the number of the chosen arms in a round, and $\tilde{O}(\cdot)$ ignores the logarithmic factors.

Decision Making Recommendation Systems

Improved Regret Bounds for Bandit Combinatorial Optimization

no code implementations NeurIPS 2019 Shinji Ito, Daisuke Hatano, Hanna Sumita, Kei Takemura, Takuro Fukunaga, Naonori Kakimura, Ken-ichi Kawarabayashi

\textit{Bandit combinatorial optimization} is a bandit framework in which a player chooses an action within a given finite set $\mathcal{A} \subseteq \{ 0, 1 \}^d$ and incurs a loss that is the inner product of the chosen action and an unobservable loss vector in $\mathbb{R} ^ d$ in each round.

Combinatorial Optimization

Oracle-Efficient Algorithms for Online Linear Optimization with Bandit Feedback

no code implementations NeurIPS 2019 Shinji Ito, Daisuke Hatano, Hanna Sumita, Kei Takemura, Takuro Fukunaga, Naonori Kakimura, Ken-ichi Kawarabayashi

Our algorithm for non-stochastic settings has an oracle complexity of $\tilde{O}( T )$ and is the first algorithm that achieves both a regret bound of $\tilde{O}( \sqrt{T} )$ and an oracle complexity of $\tilde{O} ( \mathrm{poly} ( T ) )$, given only linear optimization oracles.

Computational Efficiency

An Arm-Wise Randomization Approach to Combinatorial Linear Semi-Bandits

no code implementations5 Sep 2019 Kei Takemura, Shinji Ito

Our empirical evaluation with artificial and real-world datasets demonstrates that the proposed algorithms with the arm-wise randomization technique outperform the existing algorithms without this technique, especially for the clustered case.

Decision Making Recommendation Systems +1

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