Search Results for author: Stephan Clémençon

Found 25 papers, 5 papers with code

Regular Variation in Hilbert Spaces and Principal Component Analysis for Functional Extremes

no code implementations2 Aug 2023 Stephan Clémençon, Nathan Huet, Anne Sabourin

Motivated by the increasing availability of data of functional nature, we develop a general probabilistic and statistical framework for extremes of regularly varying random elements $X$ in $L^2[0, 1]$.

Dimensionality Reduction

On Regression in Extreme Regions

1 code implementation6 Mar 2023 Nathan Huet, Stephan Clémençon, Anne Sabourin

The statistical learning problem consists in building a predictive function $\hat{f}$ based on independent copies of $(X, Y)$ so that $Y$ is approximated by $\hat{f}(X)$ with minimum (squared) error.

regression

On Medians of (Randomized) Pairwise Means

no code implementations1 Nov 2022 Pierre Laforgue, Stephan Clémençon, Patrice Bertail

Tournament procedures, recently introduced in Lugosi & Mendelson (2016), offer an appealing alternative, from a theoretical perspective at least, to the principle of Empirical Risk Minimization in machine learning.

Metric Learning

A Statistical Learning View of Simple Kriging

no code implementations15 Feb 2022 Emilia Siviero, Emilie Chautru, Stephan Clémençon

The prediction rule being derived from a training spatial dataset: a single realization $X'$ of $X$, independent from those to be predicted, observed at $n\geq 1$ locations $\sigma_1,\; \ldots,\; \sigma_n$ in $S$.

Gaussian Processes

Improving the quality control of seismic data through active learning

no code implementations17 Jan 2022 Mathieu Chambefort, Raphaël Butez, Emilie Chautru, Stephan Clémençon

Each denoise step is then ideally followed by a quality control (QC) stage performed by means of human expertise.

Active Learning Geophysics +3

Functional Anomaly Detection: a Benchmark Study

no code implementations13 Jan 2022 Guillaume Staerman, Eric Adjakossa, Pavlo Mozharovskyi, Vera Hofer, Jayant Sen Gupta, Stephan Clémençon

After an overview of the state-of-the-art and a visual-descriptive study, a variety of anomaly detection methods are compared.

Anomaly Detection Descriptive

Fighting Selection Bias in Statistical Learning: Application to Visual Recognition from Biased Image Databases

no code implementations6 Sep 2021 Stephan Clémençon, Pierre Laforgue, Robin Vogel

In practice, and especially when training deep neural networks, visual recognition rules are often learned based on various sources of information.

Learning Theory Selection bias

Individual Survival Curves with Conditional Normalizing Flows

no code implementations27 Jul 2021 Guillaume Ausset, Tom Ciffreo, Francois Portier, Stephan Clémençon, Timothée Papin

Survival analysis, or time-to-event modelling, is a classical statistical problem that has garnered a lot of interest for its practical use in epidemiology, demographics or actuarial sciences.

Epidemiology Survival Analysis

Nearest Neighbour Based Estimates of Gradients: Sharp Nonasymptotic Bounds and Applications

no code implementations26 Jun 2020 Guillaume Ausset, Stephan Clémençon, François Portier

Motivated by a wide variety of applications, ranging from stochastic optimization to dimension reduction through variable selection, the problem of estimating gradients accurately is of crucial importance in statistics and learning theory.

Dimensionality Reduction Disentanglement +4

Generalization Bounds in the Presence of Outliers: a Median-of-Means Study

no code implementations9 Jun 2020 Pierre Laforgue, Guillaume Staerman, Stephan Clémençon

In contrast to the empirical mean, the Median-of-Means (MoM) is an estimator of the mean $\theta$ of a square integrable r. v.

Generalization Bounds Metric Learning

A Multiclass Classification Approach to Label Ranking

no code implementations21 Feb 2020 Stephan Clémençon, Robin Vogel

However, in a wide variety of situations, the task targeted may be more ambitious, consisting in sorting all the possible label values $y$ that may be assigned to $X$ by decreasing order of the posterior probability $\eta_y(X)=\mathbb{P}\{Y=y \mid X \}$.

Classification General Classification +1

Learning Fair Scoring Functions: Bipartite Ranking under ROC-based Fairness Constraints

no code implementations19 Feb 2020 Robin Vogel, Aurélien Bellet, Stephan Clémençon

We establish generalization bounds for scoring functions learned under such constraints, design practical learning algorithms and show the relevance our approach with numerical experiments on real and synthetic data.

Fairness Generalization Bounds +1

The Area of the Convex Hull of Sampled Curves: a Robust Functional Statistical Depth Measure

2 code implementations9 Oct 2019 Guillaume Staerman, Pavlo Mozharovskyi, Stephan Clémençon

a statistical population may play a crucial role in this regard, anomalies corresponding to observations with 'small' depth.

Fraud Detection Management +3

Statistical Learning from Biased Training Samples

no code implementations28 Jun 2019 Stephan Clémençon, Pierre Laforgue

With the deluge of digitized information in the Big Data era, massive datasets are becoming increasingly available for learning predictive models.

Selection bias

Trade-offs in Large-Scale Distributed Tuplewise Estimation and Learning

1 code implementation21 Jun 2019 Robin Vogel, Aurélien Bellet, Stephan Clémençon, Ons Jelassi, Guillaume Papa

The development of cluster computing frameworks has allowed practitioners to scale out various statistical estimation and machine learning algorithms with minimal programming effort.

BIG-bench Machine Learning Clustering +2

Functional Isolation Forest

1 code implementation9 Apr 2019 Guillaume Staerman, Pavlo Mozharovskyi, Stephan Clémençon, Florence d'Alché-Buc

For the purpose of monitoring the behavior of complex infrastructures (e. g. aircrafts, transport or energy networks), high-rate sensors are deployed to capture multivariate data, generally unlabeled, in quasi continuous-time to detect quickly the occurrence of anomalies that may jeopardize the smooth operation of the system of interest.

Anomaly Detection

On Binary Classification in Extreme Regions

no code implementations NeurIPS 2018 Hamid Jalalzai, Stephan Clémençon, Anne Sabourin

In pattern recognition, a random label Y is to be predicted based upon observing a random vector X valued in $\mathbb{R}^d$ with d>1 by means of a classification rule with minimum probability of error.

Binary Classification Classification +1

Dimensionality Reduction and (Bucket) Ranking: a Mass Transportation Approach

1 code implementation15 Oct 2018 Mastane Achab, Anna Korba, Stephan Clémençon

Whereas most dimensionality reduction techniques (e. g. PCA, ICA, NMF) for multivariate data essentially rely on linear algebra to a certain extent, summarizing ranking data, viewed as realizations of a random permutation $\Sigma$ on a set of items indexed by $i\in \{1,\ldots,\; n\}$, is a great statistical challenge, due to the absence of vector space structure for the set of permutations $\mathfrak{S}_n$.

Dimensionality Reduction

Autoencoding any Data through Kernel Autoencoders

no code implementations28 May 2018 Pierre Laforgue, Stephan Clémençon, Florence d'Alché-Buc

This paper investigates a novel algorithmic approach to data representation based on kernel methods.

Profitable Bandits

no code implementations8 May 2018 Mastane Achab, Stephan Clémençon, Aurélien Garivier

We adapt and study three well-known strategies in this purpose, that were proved to be most efficient in other settings: kl-UCB, Bayes-UCB and Thompson Sampling.

Management Thompson Sampling

Ranking Data with Continuous Labels through Oriented Recursive Partitions

no code implementations NeurIPS 2017 Stephan Clémençon, Mastane Achab

This problem generalizes bi/multi-partite ranking to a certain extent and the task of finding optimal scoring functions s(x) can be naturally cast as optimization of a dedicated functional criterion, called the IROC curve here, or as maximization of the Kendall ${\tau}$ related to the pair (s(X), Y ).

Ranking Median Regression: Learning to Order through Local Consensus

no code implementations31 Oct 2017 Stephan Clémençon, Anna Korba, Eric Sibony

In the probabilistic formulation of the 'Learning to Order' problem we propose, which extends the framework for statistical Kemeny ranking aggregation developped in \citet{CKS17}, this boils down to recovering conditional Kemeny medians of $\Sigma$ given $X$ from i. i. d.

regression

Max K-armed bandit: On the ExtremeHunter algorithm and beyond

no code implementations27 Jul 2017 Mastane Achab, Stephan Clémençon, Aurélien Garivier, Anne Sabourin, Claire Vernade

This paper is devoted to the study of the max K-armed bandit problem, which consists in sequentially allocating resources in order to detect extreme values.

Mass Volume Curves and Anomaly Ranking

no code implementations3 May 2017 Stephan Clémençon, Albert Thomas

Here we formulate the issue of scoring anomalies as a M-estimation problem by means of a novel functional performance criterion, referred to as the Mass Volume curve (MV curve in short), whose optimal elements are strictly increasing transforms of the density almost everywhere on the support of the density.

Generalization Bounds

On Graph Reconstruction via Empirical Risk Minimization: Fast Learning Rates and Scalability

no code implementations NeurIPS 2016 Guillaume Papa, Aurélien Bellet, Stephan Clémençon

The problem of predicting connections between a set of data points finds many applications, in systems biology and social network analysis among others.

Clustering Graph Reconstruction

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