Search Results for author: Alexia Atsidakou

Found 6 papers, 1 papers with code

Finite-Time Logarithmic Bayes Regret Upper Bounds

no code implementations15 Jun 2023 Alexia Atsidakou, Branislav Kveton, Sumeet Katariya, Constantine Caramanis, Sujay Sanghavi

In a multi-armed bandit, we obtain $O(c_\Delta \log n)$ and $O(c_h \log^2 n)$ upper bounds for an upper confidence bound algorithm, where $c_h$ and $c_\Delta$ are constants depending on the prior distribution and the gaps of bandit instances sampled from it, respectively.

Bayesian Fixed-Budget Best-Arm Identification

no code implementations15 Nov 2022 Alexia Atsidakou, Sumeet Katariya, Sujay Sanghavi, Branislav Kveton

We also provide a lower bound on the probability of misidentification in a $2$-armed Bayesian bandit and show that our upper bound (almost) matches it for any budget.

Contextual Pandora's Box

no code implementations26 May 2022 Alexia Atsidakou, Constantine Caramanis, Evangelia Gergatsouli, Orestis Papadigenopoulos, Christos Tzamos

Pandora's Box is a fundamental stochastic optimization problem, where the decision-maker must find a good alternative while minimizing the search cost of exploring the value of each alternative.

Multi-Armed Bandits Stochastic Optimization

Towards Statistical and Computational Complexities of Polyak Step Size Gradient Descent

no code implementations15 Oct 2021 Tongzheng Ren, Fuheng Cui, Alexia Atsidakou, Sujay Sanghavi, Nhat Ho

We study the statistical and computational complexities of the Polyak step size gradient descent algorithm under generalized smoothness and Lojasiewicz conditions of the population loss function, namely, the limit of the empirical loss function when the sample size goes to infinity, and the stability between the gradients of the empirical and population loss functions, namely, the polynomial growth on the concentration bound between the gradients of sample and population loss functions.

Combinatorial Blocking Bandits with Stochastic Delays

no code implementations22 May 2021 Alexia Atsidakou, Orestis Papadigenopoulos, Soumya Basu, Constantine Caramanis, Sanjay Shakkottai

Recent work has considered natural variations of the multi-armed bandit problem, where the reward distribution of each arm is a special function of the time passed since its last pulling.

Blocking

Parallel Model Exploration for Tumor Treatment Simulations

1 code implementation25 Mar 2021 Charilaos Akasiadis, Miguel Ponce-de-Leon, Arnau Montagud, Evangelos Michelioudakis, Alexia Atsidakou, Elias Alevizos, Alexander Artikis, Alfonso Valencia, Georgios Paliouras

The main challenges are first to calibrate the simulators so as to reproduce real-world cases, and second, to search for specific values of the parameter space concerning effective drug treatments.

Computational Efficiency Drug Discovery

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