Search Results for author: Alexandra Carpentier

Found 30 papers, 1 papers with code

Active Ranking of Experts Based on their Performances in Many Tasks

no code implementations5 Jun 2023 El Mehdi Saad, Nicolas Verzelen, Alexandra Carpentier

We consider the problem of ranking n experts based on their performances on d tasks.

Online Learning with Feedback Graphs: The True Shape of Regret

no code implementations5 Jun 2023 Tomáš Kocák, Alexandra Carpentier

Sequential learning with feedback graphs is a natural extension of the multi-armed bandit problem where the problem is equipped with an underlying graph structure that provides additional information - playing an action reveals the losses of all the neighbors of the action.

The price of unfairness in linear bandits with biased feedback

no code implementations18 Mar 2022 Solenne Gaucher, Alexandra Carpentier, Christophe Giraud

We also derive gap-dependent upper bounds on the regret, and matching lower bounds for some problem instance. Interestingly, these results reveal a transition between a regime where the problem is as difficult as its unbiased counterpart, and a regime where it can be much harder.

Attribute Decision Making

Problem Dependent View on Structured Thresholding Bandit Problems

no code implementations18 Jun 2021 James Cheshire, Pierre Ménard, Alexandra Carpentier

Taking $K$ as the number of arms, we consider the case where (i) the sequence of arm's means $(\mu_k)_{k=1}^K$ is monotonically increasing (MTBP) and (ii) the case where $(\mu_k)_{k=1}^K$ is concave (CTBP).

Bandits with many optimal arms

no code implementations NeurIPS 2021 Rianne de Heide, James Cheshire, Pierre Ménard, Alexandra Carpentier

We characterize the optimal learning rates both in the cumulative regret setting, and in the best-arm identification setting in terms of the problem parameters $T$ (the budget), $p^*$ and $\Delta$.

Generalized non-stationary bandits

no code implementations1 Feb 2021 Anne Gael Manegueu, Alexandra Carpentier, Yi Yu

On top of the switching bandit problem (\textbf{Case a}), we are interested in three concrete examples: (\textbf{b}) the means of the arms are local polynomials, (\textbf{c}) the means of the arms are locally smooth, and (\textbf{d}) the gaps of the arms have a bounded number of inflexion points and where the highest arm mean cannot vary too much in a short range.

The Elliptical Potential Lemma Revisited

no code implementations20 Oct 2020 Alexandra Carpentier, Claire Vernade, Yasin Abbasi-Yadkori

This note proposes a new proof and new perspectives on the so-called Elliptical Potential Lemma.

LEMMA

Stochastic bandits with arm-dependent delays

no code implementations ICML 2020 Anne Gael Manegueu, Claire Vernade, Alexandra Carpentier, Michal Valko

Significant work has been recently dedicated to the stochastic delayed bandit setting because of its relevance in applications.

The Influence of Shape Constraints on the Thresholding Bandit Problem

no code implementations17 Jun 2020 James Cheshire, Pierre Menard, Alexandra Carpentier

We prove that the minimax rates for the regret are (i) $\sqrt{\log(K)K/T}$ for TBP, (ii) $\sqrt{\log(K)/T}$ for MTBP, (iii) $\sqrt{K/T}$ for UTBP and (iv) $\sqrt{\log\log K/T}$ for CTBP, where $K$ is the number of arms and $T$ is the budget.

Restless dependent bandits with fading memory

no code implementations25 Jun 2019 Oleksandr Zadorozhnyi, Gilles Blanchard, Alexandra Carpentier

The analysis of slow mixing scenario is supported with a minmax lower bound, which (up to a $\log(T)$ factor) matches the obtained upper bound.

Linear Bandits with Stochastic Delayed Feedback

no code implementations ICML 2020 Claire Vernade, Alexandra Carpentier, Tor Lattimore, Giovanni Zappella, Beyza Ermis, Michael Brueckner

Stochastic linear bandits are a natural and well-studied model for structured exploration/exploitation problems and are widely used in applications such as online marketing and recommendation.

Marketing Multi-Armed Bandits

An Adaptive Strategy for Active Learning with Smooth Decision Boundary

no code implementations25 Nov 2017 Andrea Locatelli, Alexandra Carpentier, Samory Kpotufe

The problem of adaptivity (to unknown distributional parameters) has remained opened since the seminal work of Castro and Nowak (2007), which first established (active learning) rates for this setting.

Active Learning General Classification

Two-sample Hypothesis Testing for Inhomogeneous Random Graphs

no code implementations4 Jul 2017 Debarghya Ghoshdastidar, Maurilio Gutzeit, Alexandra Carpentier, Ulrike Von Luxburg

Given a population of $m$ graphs from each model, we derive minimax separation rates for the problem of testing $P=Q$ against $d(P, Q)>\rho$.

Two-sample testing Vocal Bursts Valence Prediction

Two-Sample Tests for Large Random Graphs Using Network Statistics

no code implementations17 May 2017 Debarghya Ghoshdastidar, Maurilio Gutzeit, Alexandra Carpentier, Ulrike Von Luxburg

We consider a two-sample hypothesis testing problem, where the distributions are defined on the space of undirected graphs, and one has access to only one observation from each model.

Two-sample testing Vocal Bursts Valence Prediction

Adaptivity to Noise Parameters in Nonparametric Active Learning

no code implementations16 Mar 2017 Andrea Locatelli, Alexandra Carpentier, Samory Kpotufe

This work addresses various open questions in the theory of active learning for nonparametric classification.

Active Learning General Classification

Tight (Lower) Bounds for the Fixed Budget Best Arm Identification Bandit Problem

no code implementations29 May 2016 Alexandra Carpentier, Andrea Locatelli

We consider the problem of \textit{best arm identification} with a \textit{fixed budget $T$}, in the $K$-armed stochastic bandit setting, with arms distribution defined on $[0, 1]$.

An optimal algorithm for the Thresholding Bandit Problem

no code implementations27 May 2016 Andrea Locatelli, Maurilio Gutzeit, Alexandra Carpentier

We study a specific \textit{combinatorial pure exploration stochastic bandit problem} where the learner aims at finding the set of arms whose means are above a given threshold, up to a given precision, and \textit{for a fixed time horizon}.

Learning relationships between data obtained independently

no code implementations4 Jan 2016 Alexandra Carpentier, Teresa Schlueter

The aim of this paper is to provide a new method for learning the relationships between data that have been obtained independently.

Upper-Confidence-Bound Algorithms for Active Learning in Multi-Armed Bandits

no code implementations16 Jul 2015 Alexandra Carpentier, Alessandro Lazaric, Mohammad Ghavamzadeh, Rémi Munos, Peter Auer, András Antos

If the variance of the distributions were known, one could design an optimal sampling strategy by collecting a number of independent samples per distribution that is proportional to their variance.

Active Learning Multi-Armed Bandits

Simple regret for infinitely many armed bandits

no code implementations18 May 2015 Alexandra Carpentier, Michal Valko

As in the cumulative regret setting of infinitely many armed bandits, the rate of the simple regret will depend on a parameter $\beta$ characterizing the distribution of the near-optimal arms.

Implementable confidence sets in high dimensional regression

no code implementations19 Jan 2015 Alexandra Carpentier

This paper focuses on constructing a confidence set for \theta which contains \theta with high probability, whose diameter is adaptive to the unknown sparsity S, and which is implementable in practice.

regression Vocal Bursts Intensity Prediction

Extreme bandits

no code implementations NeurIPS 2014 Alexandra Carpentier, Michal Valko

In many areas of medicine, security, and life sciences, we want to allocate limited resources to different sources in order to detect extreme values.

Network Intrusion Detection

Adaptive Stratified Sampling for Monte-Carlo integration of Differentiable functions

no code implementations NeurIPS 2012 Alexandra Carpentier, Rémi Munos

We consider the problem of adaptive stratified sampling for Monte Carlo integration of a differentiable function given a finite number of evaluations to the function.

Online allocation and homogeneous partitioning for piecewise constant mean-approximation

no code implementations NeurIPS 2012 Alexandra Carpentier, Odalric-Ambrym Maillard

We here consider an extension of this problem to the case when the arms are the cells of a finite partition P of a continuous sampling space X \subset \Real^d.

Active Learning

Sparse Recovery with Brownian Sensing

no code implementations NeurIPS 2011 Alexandra Carpentier, Odalric-Ambrym Maillard, Rémi Munos

We consider the problem of recovering the parameter alpha in R^K of a sparse function f, i. e. the number of non-zero entries of alpha is small compared to the number K of features, given noisy evaluations of f at a set of well-chosen sampling points.

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