2025Activity reportProject-TeamMAASAI
RNSR: 202023544J- Research centerInria Centre at Université Côte d'Azur
- In partnership with:Université Côte d'Azur
- Team name: Models and Algorithms for Artificial Intelligence
- In collaboration with:Laboratoire informatique, signaux systèmes de Sophia Antipolis (I3S), Laboratoire Jean-Alexandre Dieudonné (JAD)
Creation of the Project-Team: 2020 February 01
Each year, Inria research teams publish an Activity Report presenting their work and results over the reporting period. These reports follow a common structure, with some optional sections depending on the specific team. They typically begin by outlining the overall objectives and research programme, including the main research themes, goals, and methodological approaches. They also describe the application domains targeted by the team, highlighting the scientific or societal contexts in which their work is situated.
The reports then present the highlights of the year, covering major scientific achievements, software developments, or teaching contributions. When relevant, they include sections on software, platforms, and open data, detailing the tools developed and how they are shared. A substantial part is dedicated to new results, where scientific contributions are described in detail, often with subsections specifying participants and associated keywords.
Finally, the Activity Report addresses funding, contracts, partnerships, and collaborations at various levels, from industrial agreements to international cooperations. It also covers dissemination and teaching activities, such as participation in scientific events, outreach, and supervision. The document concludes with a presentation of scientific production, including major publications and those produced during the year.
Keywords
Computer Science and Digital Science
- A3.1. Data
- A3.1.10. Heterogeneous data
- A3.1.11. Structured data
- A3.4. Machine learning and statistics
- A9. Artificial intelligence
- A9.2. Machine learning
- A9.2.1. Supervised learning
- A9.2.2. Unsupervised learning
- A9.2.6. Neural networks
- A9.2.7. Kernel methods
- A9.2.8. Deep learning
Other Research Topics and Application Domains
- B3.6. Ecology
- B3.6.1. Biodiversity
- B6.3.4. Social Networks
- B7.2.1. Smart vehicles
- B8.2. Connected city
- B9.6. Humanities
1 Team members, visitors, external collaborators
Research Scientists
- Pierre-Alexandre Mattei [INRIA, Researcher]
- Remy Sun [INRIA, ISFP]
Faculty Members
- Charles Bouveyron [Team leader, INRIA & UNIV COTE D'AZUR, Professor, HDR]
- Marco Corneli [UNIV COTE D'AZUR, Associate Professor]
- Arnaud Droit [INRIA, Professor, from Feb 2025 until Mar 2025]
- Frederic Precioso [UNIV COTE D'AZUR, Professor]
- Michel Riveill [UNIV COTE D'AZUR, Professor]
- Vincent Vandewalle [UNIV COTE D'AZUR, Professor, HDR]
PhD Students
- Davide Adamo [CNRS]
- Elisa Ancarani [UNIV COTE D'AZUR, from Oct 2025]
- Kilian Burgi [UNIV COTE D'AZUR, until Oct 2025]
- Célia Dcruz [UNIV COTE D'AZUR]
- Dieu-Donné Fangnon [CNRS, from Apr 2025]
- Mariam Grigoryan [UNIV COTE D'AZUR]
- Maya Guy [UNIV COTE D'AZUR, from Mar 2025]
- Nicolas Lacroix [UNIV COTE D'AZUR, from Feb 2025]
- Seydina Ousmane Niang [UNIV COTE D'AZUR]
- Raphael Razafindralambo [INRIA, from Feb 2025]
- Raphael Razafindralambo [INRIA, until Jan 2025]
- Julie Tores [UNIV COTE D'AZUR]
Technical Staff
- Mathieu Lacage [INRIA, Engineer, from Jun 2025]
- Axel Velez [INRIA, Engineer, from Apr 2025]
- Li Yang [CNRS, Engineer, until Jun 2025]
Interns and Apprentices
- Muhammad Hasham Waseem Abbasi [INRIA, Intern, from Apr 2025 until Aug 2025]
- Bence Zsolt Beregi [UNIV COTE D'AZUR, Intern, from Mar 2025 until Sep 2025]
- Juliette Girardin [UNIV COTE D'AZUR, Intern, from Dec 2025]
- Juliette Girardin [UNIV COTE D'AZUR, from May 2025 until Sep 2025]
- Theo Millot [INRIA, Intern, from Apr 2025 until Sep 2025]
- Vedang Bhupesch Shenvi Nadkarni [INRIA, Intern, until May 2025]
- Zhiqiang Yu [UNIV COTE D'AZUR, from Jul 2025 until Sep 2025]
Administrative Assistant
- Claire Senica [INRIA]
Visiting Scientists
- Félix Mejia Cajica [Univ Santander, until Jan 2025]
- Federico Raspanti [UNIV COTE D'AZUR]
- Pradeep Singh [IIIT Delhi, from Aug 2025 until Nov 2025]
- Sabrina Villata [Univ Torino, from Sep 2025 until Nov 2025]
External Collaborators
- Alexandre Destere [CHU NICE]
- Pierre Latouche [UNIV CLERMONT AUVERG]
- Diane Lingrand [UNIV COTE D'AZUR, until Aug 2025]
2 Overall objectives
Artificial intelligence has become a key element in most scientific fields and is now part of everyone life thanks to the digital revolution. Statistical, machine and deep learning methods are involved in most scientific applications where a decision has to be made, such as medical diagnosis, autonomous vehicles or text analysis. The recent and highly publicized results of artificial intelligence should not hide the remaining and new problems posed by modern data. Indeed, despite the recent improvements due to deep learning, the nature of modern data has brought new specific issues. For instance, learning with high-dimensional, atypical (networks, functions, …), dynamic, or heterogeneous data remains difficult for theoretical and algorithmic reasons. The recent establishment of deep learning has also opened new questions such as: How to learn in an unsupervised or weakly-supervised context with deep architectures? How to design a deep architecture for a given situation? How to learn with evolving and corrupted data?
To address these questions, the Maasai team focuses on topics such as unsupervised learning, theory of deep learning, adaptive and robust learning, and learning with high-dimensional or heterogeneous data. The Maasai team conducts a research that links practical problems, that may come from industry or other scientific fields, with the theoretical aspects of Mathematics and Computer Science. In this spirit, the Maasai project-team is totally aligned with the “Core elements of AI” axis of the Institut 3IA Côte d’Azur. It is worth noticing that the team hosts three 3IA chairs of the Institut 3IA Côte d’Azur, as well as several PhD students funded by the Institut.
3 Research program
Within the research strategy explained above, the Maasai project-team aims at developing statistical, machine and deep learning methodologies and algorithms to address the following four axes.
Unsupervised learning
The first research axis is about the development of models and algorithms designed for unsupervised learning with modern data. Let us recall that unsupervised learning — the task of learning without annotations — is one of the most challenging learning challenges. Indeed, if supervised learning has seen emerging powerful methods in the last decade, their requirement for huge annotated data sets remains an obstacle for their extension to new domains. In addition, the nature of modern data significantly differs from usual quantitative or categorical data. We ambition in this axis to propose models and methods explicitly designed for unsupervised learning on data such as high-dimensional, functional, dynamic or network data. All these types of data are massively available nowadays in everyday life (omics data, smart cities, ...) and they remain unfortunately difficult to handle efficiently for theoretical and algorithmic reasons. The dynamic nature of the studied phenomena is also a key point in the design of reliable algorithms.
On the one hand, we direct our efforts towards the development of unsupervised learning methods (clustering, dimension reduction) designed for specific data types: high-dimensional, functional, dynamic, text or network data. Indeed, even though those kinds of data are more and more present in every scientific and industrial domains, there is a lack of sound models and algorithms to learn in an unsupervised context from such data. To this end, we have to face problems that are specific to each data type: How to overcome the curse of dimensionality for high-dimensional data? How to handle multivariate functional data / time series? How to handle the activity length of dynamic networks? On the basis of our recent results, we ambition to develop generative models for such situations, allowing the modeling and the unsupervised learning from such modern data.
On the other hand, we focus on deep generative models (statistical models based on neural networks) for clustering and semi-supervised classification. Neural network approaches have demonstrated their efficiency in many supervised learning situations and it is of great interest to be able to use them in unsupervised situations. Unfortunately, the transfer of neural network approaches to the unsupervised context is made difficult by the huge amount of model parameters to fit and the absence of objective quantity to optimize in this case. We therefore study and design model-based deep learning methods that can handle unsupervised or semi-supervised problems in a statistically grounded way.
Finally, we also aim at developing explainable unsupervised models that can ease the interaction with the practitioners and their understanding of the results. There is an important need for such models, in particular when working with high-dimensional or text data. Indeed, unsupervised methods, such as clustering or dimension reduction, are widely used in application fields such as medicine, biology or digital humanities. In all these contexts, practitioners are in demand of efficient learning methods which can help them to make good decisions while understanding the studied phenomenon. To this end, we aim at proposing generative and deep models that encode parsimonious priors, allowing in turn an improved understanding of the results.
Understanding (deep) learning models
The second research axis is more theoretical, and aims at improving our understanding of the behavior of modern machine learning models (including, but not limited to, deep neural networks). Although deep learning methods and other complex machine learning models are obviously at the heart of artificial intelligence, they clearly suffer from an overall weak knowledge of their behavior, leading to a general lack of understanding of their properties. These issues are barriers to the wide acceptance of the use of AI in sensitive applications, such as medicine, transportation, or defense. We aim at combining statistical (generative) models with deep learning algorithms to justify existing results, and allow a better understanding of their performances and their limitations.
We particularly focus on researching ways to understand, interpret, and possibly explain the predictions of modern, complex machine learning models. We both aim at studying the empirical and theoretical properties of existing techniques (like the popular LIME), and at developing new frameworks for interpretable machine learning (for example based on deconvolutions or generative models). Among the relevant application domains in this context, we focus notably on text and biological data.
Another question of interest is: what are the statistical properties of deep learning models and algorithms? Our goal is to provide a statistical perspective on the architectures, algorithms, loss functions and heuristics used in deep learning. Such a perspective can reveal potential issues in exisiting deep learning techniques, such as biases or miscalibration. Consequently, we are also interested in developing statistically principled deep learning architectures and algorithms, which can be particularly useful in situations where limited supervision is available, and when accurate modeling of uncertainties is desirable.
Adaptive and Robust Learning
The third research axis aims at designing new learning algorithms which can learn incrementally, adapt to new data and/or new context, while providing predictions robust to biases even if the training set is small.
For instance, we have designed an innovative method of so-called cumulative learning, which allows to learn a convolutional representation of data when the learning set is (very) small. The principle is to extend the principle of Transfer Learning, by not only training a model on one domain to transfer it once to another domain (possibly with a fine-tuning phase), but to repeat this process for as many domains as available. We have evaluated our method on mass spectrometry data for cancer detection. The difficulty of acquiring spectra does not allow to produce sufficient volumes of data to benefit from the power of deep learning. Thanks to cumulative learning, small numbers of spectra acquired for different types of cancer, on different organs of different species, all together contribute to the learning of a deep representation that allows to obtain unequalled results from the available data on the detection of the targeted cancers. This extension of the well-known Transfer Learning technique can be applied to any kind of data.
We also investigate active learning techniques. We have for example proposed an active learning method for deep networks based on adversarial attacks. An unlabeled sample which becomes an adversarial example under the smallest perturbations is selected as a good candidate by our active learning strategy. This does not only allow to train incrementally the network but also makes it robust to the attacks chosen for the active learning process.
Finally, we address the problem of biases for deep networks by combining domain adaptation approaches with Out-Of-Distribution detection techniques.
Learning with heterogeneous and corrupted data
The last research axis is devoted to making machine learning models more suitable for real-world, "dirty" data. Real-world data rarely consist in a single kind of Euclidean features, and are genereally heterogeneous. Moreover, it is common to find some form of corruption in real-world data sets: for example missing values, outliers, label noise, or even adversarial examples.
Heterogeneous and non-Euclidean data are indeed part of the most important and sensitive applications of artificial intelligence. As a concrete example, in medicine, the data recorded on a patient in an hospital range from images to functional data and networks. It is obviously of great interest to be able to account for all data available on the patients to propose a diagnostic and an appropriate treatment. Notice that this also applies to autonomous cars, digital humanities and biology. Proposing unified models for heterogeneous data is an ambitious task, but first attempts on combination of two data types have shown that more general models are feasible and significantly improve the performances. We also address the problem of conciliating structured and non-structured data, as well as data of different levels (individual and contextual data).
On the basis of our previous works (notably on the modeling of networks and texts), we first intend to continue to propose generative models for (at least two) different types of data. Among the target data types for which we would like to propose generative models, we can cite images and biological data, networks and images, images and texts, and texts and ordinal data. To this end, we explore modelings through common latent spaces or by hybridizing several generative models within a global framework. We are also interested in including potential corruption processes into these heterogeneous generative models. For example, we are developing new models that can handle missing values, under various sorts of missingness assumptions.
Besides the modeling point of view, we are also interested in making existing algorithms and implementations more fit for "dirty data". We study in particular ways to robustify algorithms, or to improve heuristics that handle missing/corrupted values or non-Euclidean features.
4 Application domains
Although the team members conduct a theoretical research in statistical and machine learning, they are committed to applying their results to solve concrete problems in the following areas:
Medicine
Most team members apply their research work to Medicine or extract theoretical AI problems from medical situations. In particular, our main applications to Medicine are focused on pharmacovigilance, medical imaging, and omics. It is worth noticing that medical applications cover all research axes of the team due to the high diversity of data types and AI questions.
Digital humanities
Another important application field for Maasai is the increasingly dynamic one of digital humanities. It is an extremely motivating field due to the very original questions that are addressed. Indeed, archeologits and historians have questions that are quite different from the usual ones in AI. This allows the team to formalize original AI problems that can be generalized to other fields, allowing to indirectly contribute to the general theory and methodology of AI. Furthermore, the team maintains an active collaboration with researchers on the study and detection of issues related to social justice (e.g. objectification) in movies. It is worth mentionning that Marco Corneli has a double appointment in Mathematics (Maasai) and Archeology (CEPAM).
Astrophysics and physical sciences
Maasai is actively interested in the emerging applications of deep and statistical learning to the fields of Astrophysics and Physical sciences. These phenomenons studied in these fields follow a number of very particular physical laws and differential equations that offer new constraints and methods to explore. As such, the team participates in a number of initiatives in collaboration with both the Observatoire de la Côte d'Azur and other inria teams specialized in scientific computation.
Other application domains
Other topics of interest of the team include autonomous vehicles, bioinformatics, multimedia and ecology.
5 Highlights of the year
- The 3IA chair of Pierre-Alexandre Mattei has been renewed by the international jury of Institut 3IA Côte d'Azur for an additional 4 years.
- Maasai was associated with two successful BPI projects: Logie IA and CO2PILOTE.
- Charles Bouveyron has delivered a keynote talk at the 7th International Conference on Statistics: Theory and Applications, Paris, France, in August 2025.
- Pierre-Alexandre Mattei has delivered a keynote talk at the 56th Journées de Statistique of the French Statistical Society, in Marseille, in June 2025.
6 Latest software developments, platforms, open data
6.1 Latest software developments
6.1.1 Indago - Web Interface
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Name:
Indago - Web Interface
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Keywords:
Clustering, Cluster, Clusters, Artificial intelligence, Unsupervised learning, Graph, Directed graphs, Graph algorithmics, Graph summaries, Graph processing, Statistical learning, Statistics, Data visualization, Graph visualization, Visualization, Information visualization
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Scientific Description:
Indago implements a textual graph clustering method based on a joint analysis of the graph structure and the content exchanged between each nodes. This allows to reach a better segmentation than what could be obtained with traditional methods. Indago's main applications are built around communication network analysis, including social networks. However, Indago can be applied on any graph-structured textual network. Thus, Indago has been tested on various data, such as tweet corpus, mail networks, scientific paper co-publication networks, etc.
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Functional Description:
Visualization platform, which, when used along with the Indago processing module, gives a tool for static clustering of a network with textual edges based on a joint analysis of the network structure and the content of the communications
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Contact:
Charles Bouveyron
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Participant:
3 anonymous participants
6.1.2 Indago - Processing Module
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Name:
Indago - Processing Module
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Keywords:
Clustering, Cluster, Clusters, Unsupervised learning, Graph, Directed graphs, Graph algorithmics, Graph summaries, Graph processing, Statistical learning, Statistics
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Scientific Description:
Indago implements a textual graph clustering method based on a joint analysis of the graph structure and the content exchanged between each nodes. This allows to reach a better segmentation than what could be obtained with traditional methods. Indago's main applications are built around communication network analysis, including social networks. However, Indago can be applied on any graph-structured textual network. Thus, Indago has been tested on various data, such as tweet corpus, mail networks, scientific paper co-publication networks, etc.
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Functional Description:
Static clustering of a network with textual edges based on a joint analysis of the network structure and the content of the communications
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Contact:
Charles Bouveyron
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Participant:
3 anonymous participants
6.1.3 SemiPy
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Name:
SemiPy: Deep semi-supervised with Python
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Keywords:
Machine learning, Semi-supervised classification, Deep learning, Pytorch, Python
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Scientific Description:
This Python library allows to train differentiable machine learning models (such as deep neural networks) in a semi-supervised way (i.e. with a dataset that is only partially labelled). It is based on the PyTorch deep learning library. In particular, pseudo-label methods based on data augmentation (such as Fixmatch) are implemented.
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Functional Description:
Train differentiable machine learning models (such as deep neural networks) in a semi-supervised way.
- URL:
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Contact:
Pierre-Alexandre Mattei
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Partner:
Naval Group
6.1.4 RO3SE
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Name:
Robust Semi-Supervised Speech Enhancement
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Keywords:
Deep learning, Speech processing, Unsupervised learning, Data augmentation
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Functional Description:
This software aims at improving the performance of speech enhancement algorithms by leveraging unsupervised/unlabeled data that correspond to real-life audio scenarios. It is composed of data augmentation methods, deep neural network architectures, semi-supervised training methods, loss functions, and evaluation tools to develop and evaluate deep-learning-based semi-supervised speech enhancement algorithms. The code is both documented and unit-tested.
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Contact:
Pierre-Alexandre Mattei
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Participant:
3 anonymous participants
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Partner:
PULSE AUDITION
6.1.5 StreamETM
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Keywords:
Machine learning, Artificial intelligence, Natural language processing
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Scientific Description:
StreamETM is an application designed for dynamic topic modeling using the Embedded Topic Model (ETM). It processes streaming text data, merges topic models over time, and detects change points in topic distributions.
Features: 1) Dynamic Topic Modeling: Continuously update topic models with new data chunks. 2) Topic Merging: Merge new topic models with existing ones to maintain a coherent topic structure. 3) Change Point Detection: Detect significant changes in topic distributions over time using Online Change Point Detection (OCPD). 4) Preprocessing: Preprocess text data, including lemmatization, stopword removal, and frequency-based filtering.
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Functional Description:
Online topic modeling using the Embedded Topic Model (ETM) to process streaming text data, merge topic models over time, and detect change points in topic distributions.
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News of the Year:
The software has been developed as part of the paper, Merging Embedded Topics with Optimal Transport for Online Topic Modeling on Data Streams (https://arxiv.org/pdf/2504.07711)
- Publication:
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Contact:
Federica Granese
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Participant:
4 anonymous participants
6.1.6 HERACLES
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Name:
Online Topic Change Point Detection
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Keywords:
Incremental clustering, Continual Learning
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Functional Description:
This script performs topic modeling on chunks of documents using BERTopic and detects change points in topic distributions over time using Online Change Point Detection (OCPD). It processes document chunks iteratively, updating the topic model with each new chunk, and identifies significant changes in topics over time.
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Contact:
Serena Villata
6.1.7 HDClassif
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Name:
High Dimensional Supervised Classification and Clustering
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Keywords:
Classification, Statistical methods
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Functional Description:
The HDclassif package is devoted to the clustering and the discriminant analysis of high-dimensional data. The classification methods proposed in the package result from a new parametrization of the Gaussian mixture model which combines the idea of dimension reduction and model constraints on the covariance matrices. The supervised classification method using this parametrization has been called High Dimensional Discriminant Analysis (HDDA). In a similar manner, the associated clustering method has been called High Dimensional Data Clustering (HDDC) and uses the Expectation-Maximization (EM) algorithm for inference. In order to correctly fit the data, both methods estimate the specific subspace and the intrinsic dimension of the groups. Due to the constraints on the covariance matrices, the number of parameters to estimate is significantly lower than other model-based methods and this allows the methods to be stable and efficient in high-dimensional spaces. Experiments on artificial and real datasets show that HDDC and HDDA perform better than existing classical methods on high-dimensional datasets, even with small datasets.
- URL:
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Contact:
Charles Bouveyron
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Participant:
3 anonymous participants
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Partner:
Université Paris-Descartes
6.2 New platforms
Cassiopy
Website: https://pypi.org/project/cassiopy/
Participants: Vincent Vandewalle.
- Software Family : vehicle;
- Audience: community;
- Evolution and maintenance: basic;
- Free Description: CassioPy is a python library for clustering using the Skew-t distribution. This model is designed to handle data with skewness, providing more accurate clustering results in many real-world scenarios where data may not follow a normal distribution.
CleverFish
Website: https://3ia-demos.inria.fr/en/demos/cleverfish/
Participants: Charles Bouveyron, Remy Sun, Diane Lingrand.
- Software Family : vehicle;
- Audience: community;
- Evolution and maintenance: basic;
- Free Description: CleverFish is a novel tool designed to bridge the gap between marine biology and AI. CleverFish tackles three core challenges of an efficient management tool: providing an easy-to-use graphical user interface, accommodating global and video-specific in app biodiversity assessment, allowing fast and efficient extraction of temporal and spatial fish species distribution in a format understandable for ecologists.
7 New results
7.1 Unsupervised learning
7.1.1 Deep Latent Position Topic Model (LPTM) for Clustering and Representation of Networks with Textual Edges
Participants: Charles Bouveyron, Rémi Boutin, Pierre Latouche.
Keywords: Generative models, Clustering, Networks, Text, Topic modeling
Numerical interactions leading to users sharing textual content published by others are naturally represented by a network where the individuals are associated with the nodes and the exchanged texts with the edges. To understand those heterogeneous and complex data structures, clustering nodes into homogeneous groups as well as rendering a comprehensible visualization of the data is mandatory. To address both issues, we introduced in 14 Deep-LPTM, a model-based clustering strategy relying on a variational graph auto-encoder approach as well as a probabilistic model to characterize the topics of discussion. Deep-LPTM allows to build a joint representation of the nodes and of the edges in two embeddings spaces. The parameters are inferred using a variational inference algorithm. We also introduce IC2L, a model selection criterion specifically designed to choose models with relevant clustering and visualization properties. An extensive benchmark study on synthetic data is provided. In particular, we find that Deep-LPTM better recovers the partitions of the nodes than the state-of-the-art ETSBM and STBM (see Figure 1). Eventually, the emails of the Enron company are analyzed and visualizations of the results are presented, with meaningful highlights of the graph structure.
The image compares four network diagrams. The "True network" on the far left shows three distinct clusters with clear connections between them. The second diagram, labeled "SBM LDA," depicts a densely interconnected network with less defined clusters. The third diagram, "ETSBM," shows a network with more structured clusters, though still interconnected. The fourth diagram, "Deep-LPTM," displays a network with distinct, clearly separated clusters similar to the true network but with some differences in connectivity. Each diagram uses different colors to indicate different clusters within the network.
Illustration of Deep-LPTM main contributions on a synthetic network.
7.1.2 A Tutorial on Discriminative Clustering and Mutual Information
Participants: Pierre-Alexandre Mattei, Louis Ohl, Frédéric Precioso.
Keywords: Clustering, Deep learning
To cluster data is to separate samples into distinctive groups that should ideally have some cohesive properties. Today, numerous clustering algorithms exist, and their differences lie essentially in what can be perceived as “cohesive properties”. Therefore, hypotheses on the nature of clusters must be set: they can be either generative or discriminative. As the last decade witnessed the impressive growth of deep clustering methods that involve neural networks to handle high-dimensional data often in a discriminative manner, we concentrate mainly on the discriminative hypotheses. In 30, our aim is to provide an accessible historical perspective on the evolution of discriminative clustering methods and notably how the nature of assumptions of the discriminative models changed over time: from decision boundaries to invariance critics. We notably highlight how mutual information has been a historical cornerstone of the progress of (deep) discriminative clustering methods. We also show some known limitations of mutual information and how discriminative clustering methods tried to circumvent those. We then discuss the challenges that discriminative clustering faces with respect to the selection of the number of clusters. Finally, we showcase these techniques using the dedicated Python package, GemClus, that we have developed for discriminative clustering.
7.1.3 Clustering by Deep Latent Position Model with Graph Convolutional Network
Participants: Charles Bouveyron, Marco Corneli.
Collaborations: Pierre Latouche, Dingge Liang
Keywords: Multiview graphs, Clustering, Variational Autoencoding Inference
With the significant increase of interactions between individuals through numeric means, clustering of vertices in graphs has become a fundamental approach for analyzing large and complex networks. In 26, we propose the deep latent position model (DeepLPM), an end-to-end generative clustering approach which combines the widely used latent position model (LPM) for network analysis with a graph convolutional network (GCN) encoding strategy. Moreover, an original estimation algorithm is introduced to integrate the explicit optimization of the posterior clustering probabilities via variational inference and the implicit optimization using stochastic gradient descent for graph reconstruction. Numerical experiments on simulated scenarios highlight the ability of DeepLPM to self-penalize the evidence lower bound for selecting the intrinsic dimension of the latent space and the number of clusters, demonstrating its clustering capabilities compared to state-of-the-art methods. Finally, DeepLPM is further applied to an ecclesiastical network in Merovingian Gaul and to a citation network Cora to illustrate the practical interest in exploring large and complex real-world networks.
7.1.4 The Multiplex Deep Latent Position Model for the Clustering of nodes in Multiview Networks
Participants: Charles Bouveyron, Marco Corneli.
Collaborations: Pierre Latouche, Dingge Liang, Junping Yin
Keywords: Multiview graphs, Clustering, Variational Autoencoding Inference
Multiplex networks capture multiple types of interactions among the same set of nodes, creating a complex, multi-relational framework. A typical example is a social network where nodes (actors) are connected by various types of ties, such as professional, familial, or social relationships. Clustering nodes in these networks is a key challenge in unsupervised learning, given the increasing prevalence of multiview data across domains. While previous research has focused on extending statistical models to handle such networks, these adaptations often struggle to fully capture complex network structures and rely on computationally intensive Markov chain Monte Carlo (MCMC) for inference, rendering them less feasible for effective network analysis. To overcome these limitations, in 27 we propose the multiplex deep latent position model (MDLPM, see Fig. 2), which generalizes and extends latent position models to multiplex networks. MDLPM combines deep learning with variational inference to effectively tackle both the modeling and computational challenges raised by multiplex networks. Unlike most existing deep learning models for graphs that require external clustering algorithms (e.g., k-means) to group nodes based on their latent embeddings, MDLPM integrates clustering directly into the learning process, enabling a fully unsupervised, end-to-end approach. This integration improves the ability to uncover and interpret clusters in multiplex networks without relying on external procedures. Numerical experiments across various synthetic data sets and two real-world networks demonstrate the performance of MDLPM compared to state-of-the-art methods, highlighting its applicability and effectiveness for multiplex network analysis.
The image depicts a framework for multiview network analysis. It starts with multiple network views processed by separate encoders, generating mean and variance outputs. These outputs are combined using MLPs (Multilayer Perceptrons) to produce latent variables. These latent variables feed into LPM-based decoders to reconstruct the original network views, facilitating the generative modeling of multiview networks.
7.1.5 Scaling Optimal Transport to High-Dimensional Gaussian Distributions
Participants: Charles Bouveyron, Marco Corneli.
Keywords: Optimal transport, High-dimensional Gaussian distributions, Subspace modeling
Although optimal transport (OT) has recently become very popular in machine learning, it faces challenges when dealing with high-dimensional data, such as images or omics data. Current OT approaches for high-dimensional situations rely on projections of the data or measures onto low-dimensional spaces, which inevitably results in information loss. In 62, we consider the case of high-dimensional Gaussian distributions with parsimonious covariance structures and lower intrinsic dimension. We exhibit a simplified closed-form expression of the 2-Wasserstein (W2) distance with an efficient and robust calculation procedure based on a low-dimensional decomposition of empirical covariance matrices, without relying on data projections. Furthermore, we provide a closed-form expression for the Monge map, which involves the exact calculation of the square-root and inverse square-root of the source distribution covariance matrix. This approach offers analytical and computational advantages, as demonstrated by our numerical experiments, which quantitatively evaluate these benefits in comparison to existing methods. In addition to being able to compute both the W2 2-distance and the transport map, our method outperforms model-free methods, in high dimension, even in the case of non-Gaussian distributions.
7.1.6 A Model-Based Clustering Approach for Toxicity Assessment Using Cell Painting Data
Participants: Mariam Grigoryan, Vincent Vandewalle.
Collaborations: David Rouquié
Keywords: Cells, Clustering
Cell Painting is a high-content imaging approach that enables the simultaneous analysis of multiple cellular compartments, providing a comprehensive view of how chemical compounds affect cell morphology and organelle organization. In this work, we study these morphological changes in a dose–response framework with the objective of identifying the Point of Departure (POD), defined as the lowest concentration at which significant morphological alterations are observed.
The dose–response problem is addressed using a two-step methodology. First, cells within each well of the assay plates are clustered using a Gaussian mixture model. In this model, cluster-specific parameters are assumed to be shared across wells, while cluster proportions are allowed to vary from one well to another. This formulation makes it possible to summarize each well by a low-dimensional vector of class proportions. In a second step, a sequential statistical testing procedure is applied to identify the minimum concentration at which a compound induces a significant shift in cell characteristics relative to negative control wells. This comparison is performed using a non-parametric permutation test on the vectors of class proportions, with tests conducted sequentially over increasing compound concentrations.
The proposed approach is applied to Cell Painting data and demonstrates its ability to detect distributional shifts in cellular phenotypes across compound concentrations, thereby providing a robust and interpretable framework for POD identification.
This work was disseminated through a poster presentation at the Model-Based Clustering Workshop (INRIA, July 21–25), a poster presentation at EUROTOX (September 14–17, Athens, Greece) (67), and an oral presentation at the Journées de Statistique (JDS, June 2–6, Marseille) (47).
7.1.7 Clustering of reccurrent events
Participants: Vincent Vandewalle.
Collaborations: Génia Babykina, Jésus Carretero-Bravo
Keywords: Clustering, Mixture models
Nowadays data are often timestamped, thus, when analyzing the events which may occur several times (recurrent events), it is desirable to model the whole dynamics of the counting process rather than to focus on a total number of events. Such kind of data can be encountered in hospital readmissions, disease recurrences or repeated failures of industrial systems. Recurrent events can be analyzed in the counting process framework, as in the Andersen-Gill model, assuming that the baseline intensity depends on time and on covariates, as in the Cox model. However, observed covariates are often insufficient to explain the observed heterogeneity in the data. We propose a mixture model for recurrent events, allowing to account for the unobserved heterogeneity and to perform clustering of individuals (unsupervised classification allowing to partition the heterogeneous data according to unobserved, or latent, variables). Within each cluster, the recurrent event process intensity is specified parametrically and is adjusted for covariates. Model parameters are estimated by maximum likelihood using the EM algorithm; the Bayesian Information Criterion (BIC) criterion is adopted to choose an optimal number of clusters. The model feasibility is checked on simulated data. Real data on hospital readmissions of elderly people, which motivated the development of the proposed clustering model, are analyzed. The obtained results allow a fine understanding of the recurrent event process in each cluster. This work has been published in 12 and also in a journal on geriarty 36.
7.1.8 Unsupervised machine learning analysis to enhance risk stratification in patients with asymptomatic aortic stenosis
Participants: Arnaud Droit, Pierre-Alexandre Mattei, Louis Ohl, Frédéric Precioso.
Collaborations: Marie-Ange Fleury, Philippe Pibarot, and other researchers from Université Laval (Québec)
Keywords: Clustering, Cardiology
There is a lack of studies investigating the pathophysiologic and phenotypic distinctiveness of aortic stenosis (AS). This heterogeneity has important implications for identifying optimal intervention timing and potential medical management. The study 19 seeks to identify phenogroups of AS using unsupervised machine learning to improve risk stratification. A total of 349 patients with asymptomatic AS from the PROGRESSA study were included in this analysis. Echocardiographic, clinical and blood sample data were used in the unsupervised clustering process. Longitudinal echocardiographic data were used to evaluate AS progression. Five clusters of patients were revealed using 18 variables selected by an unsupervised machine learning algorithm (see Fig. 3). This approach may be useful to optimize and individualize medical and interventional management of AS.
The image illustrates a generative model for multiview networks. It consists of multiple network views processed by separate encoders. These encoders generate mean and standard deviation values, which are fed into Multilayer Perceptrons (MLPs) to produce latent variables. These variables, along with a shared parameter, are then input into LPM-based decoders. The decoders reconstruct the network views, creating a final reconstructed network. The flow demonstrates an inference procedure that transforms multiview networks into reconstructed versions through encoding and decoding processes.
7.1.9 Non parametric multiple partition clustering
Participants: Vincent Vandewalle.
Collaborations: Marie Du Roy de Chaumaray, Matthieu Marbac-Lourdelle
Keywords: Clustering, Mixture Models
In the framework of model-based clustering, a model, called multi-partitions clustering, allowing several latent class variables has been proposed. This model assumes that the distribution of the observed data can be factorized into several independent blocks of variables, each block following its own mixture model. In this study, we assume that each block follows a non-parametric latent class model, i.e. independence of the variables in each component of the mixture with no parametric assumption on their class conditional distribution. The purpose is to deduce, from the observation of a sample, the number of blocks, the partition of the variables into the blocks and the number of components in each block, which characterize the proposed model. By following recent literature on model and variable selection in non-parametric mixture models, we propose to discretize the data into bins. This permits to apply the classical multi-partition clustering procedure for parametric multinomials, which are based on a penalized likelihood method (e.g. BIC). The consistency of the procedure is obtained and an efficient optimization is proposed. The performances of the model are investigated on simulated data. This work has been presented in 39, and also in 40.
7.1.10 An EM Stopping Rule for Avoiding Degeneracy in Gaussian-based Clustering with Missing Data
Participants: Vincent Vandewalle.
Collaborations: Christophe Biernacki
Keywords: Expectation-Minimization, Clustering
Missing data frequency increases with the growing size of multivariate modern datasets. In Gaussian model-based clustering, the EM algorithm easily takes into account such data but the degeneracy problem is dramatically aggravated during the EM runs: parameter degeneracy is quite slow and also more frequent than with complete data. Consequently, parameter degenerated solutions may be confused with valuable parameter solutions and, in addition, computing time may be wasted through wrong runs. In this work, a simple and low informational condition on the latent partition allows to propose a very simple partition-based stopping rule of EM which shows good behavior on numerical experiments. This work has been presented in 38.
7.1.11 Unveiling Hidden Structures in the Main Belt: A Probabilistic Framework for Asteroid Families
Participants: Maya Guy, Vincent Vandewalle.
Keywords: Asteroids, Asteroid families, Probabilistic models, Clustering
Collaborations: Benoit Carry
The identification of asteroid families is a key question in planetary sciences, offering crucial insights into the collisional and dynamical history of the asteroid Main Belt (MB). These families, originating from the fragmentation of parent bodies due to catastrophic collisions, form dense clusters in orbital space. Over time, the non-gravitational Yarkovsky effect induces a semi-major axis drift, producing the characteristic V-shaped patterns in the (semi-major axis, absolute magnitude) plane. Current techniques for family identification suffer from several limitations. The most widely used approach, the Hierarchical Clustering Method (HCM), does not account for the presence of a background population, leading to overestimated family cores and the omission of their extended wings. Furthermore, no families older than 2Gyr have been confidently identified using this method. Additionally, HCM assumes that families are non-overlapping in the proper element space, an unrealistic assumption as young families may overlap with older, more diffuse, families. To overcome some of the HCM limitation, the V-shape method was developed. Being based on the print of Yarkovsky-induced spreading, it successfully allowed to find very old families. While recent combined approaches have incorporated the background population into family detection frameworks, they still lack an intrinsic mechanism for handling overlapping families and do not yield probabilistic membership lists. In this study (68), we propose a new probabilistic approach for identifying asteroid families in the MB, using model-based clustering. We model the observed population of the MB as a mixture of skewed-t distributions for eccentricity, inclination, and absolute magnitude, coupled with a gaussian distribution for semi-major axis that explicitly depends on absolute magnitude which captures the Yarkovsky-driven semi-major axis evolution. The parameters, which define the shape and orientation of each cluster along each dimension, and mixture proportions of the model are estimated using the Expectation-Maximization (EM) algorithm. This model also includes a uniform background component for the primordial asteroid population. This flexible approach accommodates anisotropic and overlapping family structures, and provides a probabilistic membership assignments, enabling a more nuanced and robust classification of asteroid families. We will present the methodology and results from simulated datasets to demonstrate the performance and advantages of this approach.
7.1.12 From Fragments to Families: Asteroid Clustering
Participants: Maya Guy, Vincent Vandewalle.
Keywords: Asteroids, Asteroid families, Probabilistic models, Clustering
Collaborations: Benoit Carry
This study 69 provides a new probabilistic approach for identifying asteroid families in the Main Belt (MB), addressing limitations of traditional methods like the Hierarchical Clustering Method (HCM). These methods often overestimate family cores, miss extended wings (halos), and struggle with identifying older families and overlapping structures. The proposed model uses skewed-t distributions for eccentricity, inclination, and absolute magnitude, coupled with a Gaussian distribution for semi-major axis evolution influenced by the Yarkovsky effect. This flexible approach accommodates anisotropic and overlapping family structures, providing probabilistic membership assignments for a more nuanced classification.
7.1.13 An in depth look at the Procrustes-Wasserstein distance: properties and barycenters
Participants: Davide Adamo, Marco Corneli.
Keywords: Optimal Transport, Procrustes Analysis; Point Cloud; Zooarchaeology
Collaborations: Manon Vuillien, Emmanuelle Vila
Due to its invariance to rigid transformations such as rotations and reflections, Procrustes-Wasserstein (PW) was introduced in the literature as an optimal transport (OT) distance, alternative to Wasserstein and more suited to tasks such as the alignment and comparison of point clouds. Having that application in mind, in 43, we carefully build a space of discrete probability measures and show that over that space PW actually is a distance. Algorithms to solve the PW problems already exist, however we extend the PW framework by discussing and testing several initialization strategies. We then introduce the notion of PW barycenter and detail an algorithm to estimate it from the data. The result is a new method to compute representative shapes from a collection of point clouds. We benchmark our method against existing OT approaches, demonstrating superior performance in scenarios requiring precise alignment and shape preservation (see Fig. 4). We finally show the usefulness of the PW barycenters in an archaeological context. Our results highlight the potential of PW in boosting 2D and 3D point cloud analysis for machine learning and computational geometry applications.
The image displays a grid of 3D models showing progressive changes from an archaeological form to a modern form. It consists of three rows labeled row1, row2, and row3, and five columns labeled from "archaeo" to "modern." Each model transitions through different stages labeled with fractions (η = 1/5, η = 2/5, η = 3/5, η = 4/5), showing a smooth transformation in shape and texture. The colors range from bright yellow to dark purple.
7.1.14 Rethinking multiple kernel learning under the lenses of Importance Weighted Monte Carlo Variational Inference
Participants: Davide Adamo, Marco Corneli.
Keywords: Multiple kernel learning, Monte Carlo variational inference, Kernel(s) selection, Importance-Weighted lower bound
Collaborations: Manon Vuillien, Emmanuelle Vila
Kernel methods have been widely used in machine learning as they are a powerful tool for implicitly mapping data into high-dimensional spaces, enabling the discovery of complex patterns that might be challenging to capture in the original feature space. Although some classification and regression problems can be successfully addressed with a single kernel, sometimes real-world scenarios exhibit complex structures, and it is desirable to employ several kernel types, one for each notion of similarity that one aims to take into account. This is where multiple kernel learning (MKL) comes into play. This paper 60 revisits multi-kernel classification with a specific focus on kernel(s) selection in the light of recent developments in Monte Carlo (importance weighted) variational inference (MCVI). In the framework of kernelized logistic regression (KLR), we consider positive semi-definite linear combinations of kernels and treat the kernel weights as random variables. Proper choices of prior distributions coupled with the explicit derivation of the importance-weighted lower bound (IW-ELBO), generalization of the traditional variational lower bound (ELBO), allow us to both perform kernel selection via shrinking and to perform posterior inference on the kernel weights, without needing MCMC sampling. Unlike pure optimization-based approaches to MKL, our optimization problem does not require explicit constraints and can be optimized by standard stochastic gradient descent (see Fig. 5).
This figure shows 10 plots of posterior densities for kernel weights in a 2x5 grid. Both the blue and orange curve on the plot folloow similar profiles, with the orange curve showing a sharper peak.
7.1.15 The Deep Zero-Inflated Latent Position Block Model for the Clustering of Nodes in Graphs
Participants: Seydina Niang, Charles Bouveyron, Marco Corneli.
Keywords: Nodes clustering, Graph variational autoencoder, Block modeling, Graph visualization, Zero-inflated Poisson
Collaborations: Pierre Latouche
The evolution in storage capacities has led to a data explosion, making networks essential for modeling relationships between objects (nodes). These complex networks require effective clustering and visualization methods to summarize and interpret their information. The deep latent position block model (Deep-LPBM), designed for binary networks, combines partial block-based clustering and continuous latent representation to visualize nodes. Here, we propose an extension, the deep zero-inflated latent position block model (Deep-ZLPBM, 55), designed for non-binary networks, where the entries of the adjacency matrix can take integer values. This model is based on a deep variational autoencoder that integrates a graph convolutional network (GCN) and a decoder leveraging a zero-inflated Poisson (ZIP) distribution. Inference relies on the maximization of the marginal likelihood, and optimization is performed using stochastic gradient descent.
7.1.16 Importance weighted directed graph variational auto-encoder for block modeling of complex networks
Participants: Seydina Niang, Charles Bouveyron, Marco Corneli.
Keywords: Nodes clustering, Graph variational autoencoder, Block modeling, Graph visualization, Zero-inflated Poisson
Collaborations: Pierre Latouche
This work addresses the fundamental challenges of jointly performing node clustering and representation learning in directed and valued graphs, which need both global and local network structures to be captured. While these two tasks are highly interdependent, they are often treated separately in existing works. We propose the deep zero-inflated latent position block model (Deep-ZLPBM, 65) in the context of directed and valued networks characterized by non-symmetric adjacency matrices with positive integer entries. Our approach leverages a variational autoencoder (VAE) framework, combining a directed graph neural network (DirGNN) encoder designed to handle directed edges and a zero-inflated Poisson (ZIP) block modeling decoder to model sparse, integer-weighted interactions. Recognizing the limitations of the standard evidence lower bound (ELBO) in VAEs, we explore the importance weighted ELBO (iw-ELBO), a tighter bound on the marginal log-likelihood optimized via gradient ascent, to enhance inference. Extensive experiments on synthetic datasets demonstrate that iw-ELBO optimization yields significant performance gains. Moreover, our results validate that Deep-ZLPBM effectively models complex network structures, providing interpretable partial memberships and insightful visualizations for directed, valued graphs.
7.2 Understanding (deep) learning models
7.2.1 Are Ensembles Getting Better all the Time?
Participants: Damien Garreau, Pierre-Alexandre Mattei.
Keywords: Ensembles, Diffusion, Random forests
Diffusion models now generate high-quality, diverse samples, with an increasing focus on more powerful models. Although ensembling is a well-known way to improve supervised models, its application to unconditional score-based diffusion models remains largely unexplored. In 31 we investigate whether it provides tangible benefits for generative modeling. We find that while ensembling the scores generally improves the score-matching loss and model likelihood, it fails to consistently enhance perceptual quality metrics such as Fréchet Inception Distance (FID) on image datasets. We confirm this observation across a breadth of aggregation rules using Deep Ensembles, Monte Carlo Dropout, on CIFAR-10 and FFHQ. We attempt to explain this discrepancy by investigating possible explanations, such as the link between score estimation and image quality. We also look into tabular data through random forests, and find that one aggregation strategy outperforms the others. Finally, we provide theoretical insights into the summing of score models, which shed light not only on ensembling but also on several model composition techniques (e.g. guidance).
7.2.2 When Are Two Scores Better Than One? Investigating Ensembles of Diffusion Models
Participants: Raphael Razafindralambo, Remy Sun, Damien Garreau, Frederic Precioso, Pierre-Alexandre Mattei.
Keywords: Ensembles, Dropout, Random forests
Ensemble methods combine the predictions of several base models. We study whether including more models always improves their average performance. This question depends on the kind of ensemble considered, as well as the predictive metric chosen. We focus on situations where all members of the ensemble are a priori expected to perform as well, which is the case of several popular methods such as random forests or deep ensembles. In this setting, we show in 28 that ensembles are getting better all the time if, and only if, the considered loss function is convex. More precisely, in that case, the average loss of the ensemble is a decreasing function of the number of models. When the loss function is nonconvex, we show a series of results that can be summarized as: ensembles of good models keep getting better, and ensembles of bad models keep getting worse. To this end, we prove a new result on the monotonicity of tail probabilities that may be of independent interest. We illustrate our results on a medical prediction problem (diagnosing melanomas using neural nets) and a "wisdom of crowds" experiment (guessing the ratings of upcoming movies).
7.2.3 Re-examining Concept-based Explainable Models for Multimodal Interpretative Tasks.
Participants: Julie Tores, Elisa Ancarani, Rémy Sun, Frédéric Precioso.
Keywords: Deep Learning, Multimedia, Concept based model, Objectification
Collaborations: Lucile Sassatelli, Hui-Yin Wu
Concept-based models have been proposed as a new line of research for explainable by-design deep learning models. However, those models show their whole power when applied to benchmarks where the concepts are well defined and the concepts' attributes easily extractable from the raw data. In 52, we challenge the most recent concept-based model initially developed for image classification, on more complex interpretative tasks from a recently proposed video benchmark where they perform poorly. We conduct a root cause analysis of the poor performances of state-of-the-art explainable concept-based models for these multimodal interpretative tasks, and propose adaptations to design robust explainable models for detecting character objectification in this novel challenging video benchmark. We show that the optimal architectural choice may vary depending on the modality setting, thereby showing that designing multimodal concept-based approaches remains an open challenge and calls for further investigation.
7.2.4 Normative Alignment of Recommender Systems via Internal Label Shift
Participants: Pierre-Alexandre Mattei.
Keywords: Deep Learning, Recommender systems, Fairness, Label Shift, Alignment
Collaborations: Johannes Kruse, Kasper Lindskow, Michael Riis Andersen, Ryotaro Shimizu, Julian McAuley, Jes Frellsen
Recommender systems optimized solely for user engagement often fail to meet broader normative objectives such as fairness, diversity, or editorial values. In 49, we introduce NAILS (Normative Alignment of recommender systems via Internal Label Shift), a simple and scalable method for aligning recommendation outputs with target distributions over item-level attributes (e.g., categories). NAILS modifies the user-conditional item distribution to induce a specified marginal distribution over attributes, leveraging existing user–item preferences without retraining the model. To achieve this, we recast the problem as a form of label shift applied internally within a hierarchical classification framework. Adopting a stakeholder-centric perspective, NAILS enables alignment with global normative goals. Empirically, we show that NAILS consistently improves attribute-level alignment with minimal impact on user engagement, providing a practical mechanism for value-driven recommendation.
7.3 Adaptive and robust learning
7.3.1 Mind the map! Accounting for existing map information when estimating online HDMaps from sensor data
Participants: Rémy Sun, Li Yang, Diane Lingrand, Frédéric Precioso.
Keywords: Autonomous Driving, HDMaps, Online HDMap estimation
Collaborations: ANR Project MultiTrans
Online High Definition Map (HDMap) estimation from sensors offers a low-cost alternative to manually acquired HDMaps. As such, it promises to lighten costs for already HDMap-reliant Autonomous Driving systems, and potentially even spread their use to new systems. We proposed in 51 to improve online HDMap estimation by accounting for already existing maps. We identify 3 reasonable types of useful existing maps (minimalist, noisy, and outdated). We also introduce MapEX (see Fig. 6), a novel online HDMap estimation framework that accounts for existing maps. MapEX achieves this by encoding map elements into query tokens and by refining the matching algorithm used to train classic query based map estimation models. We demonstrate that MapEX brings significant improvements on the nuScenes dataset. For instance, given noisy maps, MapEX improves by 38% over the MapTRv2 detector it is based on and by 16% over the current SOTA (state-of-the-art).
This figure shows input images being put through a grey shape called BEV encoder to output a grid of features. On the other hand, a map is transformed into colored square features. Both type of features are put through a gray shape called decoder to output a row of colored boxes that get decoded into map elements.
Overview of our MapEX method (see Sec. 7.3.1). We add two modules (EX query encoding, Attribution) to the standard query based map estimation pipeline (in gray on the figure). Map elements are encoded into EX queries, then decoded with a standard decoder.
7.3.2 Efficiency in the classification of chest X-ray images through generative parallelization of the Neural Architecture Search
Participants: Michel Riveill.
Keywords: Deep Learning, Neural Architecture Search, X-ray
Collaborations: Felix Mejía Cajicá, John Anderson García Henao, Carlos Jaime Barrios Hernandéz
29 explores Generic Neural Architecture Search (GenNAS) for chest X-ray classification in lung diseases, leveraging novel parallel training methods for enhanced accuracy and efficiency. Medical image classification for pulmonary pathologies from chest X-rays is traditionally time-consuming. GenNAS, using GPT-4's generative capabilities, automates optimal architecture learning from data. This study investigates parallelization and generative algorithms to optimize neural network architectures for chest X-ray classification, analyzing their impact on the NAS algorithm using the ChexPert dataset. The study uses the CheXpert dataset with 224,316 chest X-rays to classify five lung disease pathologies. GenNASXRays evaluates 6561 architecture possibilities in an 8-layer search space, with AUC-ROC and Precision-Recall plots as metrics. Training on 187,641 images, the sequential algorithm took 190.2 hours for an AUC-ROC of 0.869. In parallel execution on two GPUs, an AUC-ROC of 0.87 was achieved in 127.09 hours, highlighting the efficiency of parallelization.
7.3.3 Parsimonious Gaussian mixture models with piecewise-constant eigenvalue profiles
Participants: Pierre-Alexandre Mattei, Charles Bouveyron.
Keywords: GMM, Low-rank, Clustering, Denoising
Collaborations: Tom Szwagier, Xavier Pennec
Gaussian mixture models (GMMs) are ubiquitous in statistical learning, particularly for unsupervised problems. While full GMMs suffer from the over-parameterization of their covariance matrices in high-dimensional spaces, spherical GMMs (with isotropic covariance matrices) certainly lack flexibility to fit certain anisotropic distributions. Connecting these two extremes, we introduce in 33 a new family of parsimonious GMMs with piecewise-constant covariance eigenvalue profiles. These extend several low-rank models like the celebrated mixtures of probabilistic principal component analyzers (MPPCA), by enabling any possible sequence of eigenvalue multiplicities. If the latter are pre-specified, then we can naturally derive an expectation-maximization (EM) algorithm to learn the mixture parameters. Otherwise, to address the notoriously-challenging issue of jointly learning the mixture parameters and hyperparameters, we propose a component-wise penalized EM algorithm, whose monotonicity is proven. We show the superior likelihood-parsimony tradeoffs achieved by our models on a variety of unsupervised experiments: density fitting, clustering and single-image denoising.
7.3.4 A Layer Selection Approach to Test Time Adaptation
Participants: Sabyasachi Sahoo, Jonas Ngawe, Frédéric Precioso.
Keywords: Deep learning, Test Time Adaptation, Distribution shift
Collaborations: Mostafa Elaraby, Yann Batiste Pequignot, Christian Gagné
Test Time Adaptation (TTA) addresses the problem of distribution shift by adapting a pretrained model to a new domain during inference. When faced with challenging shifts, most methods collapse and perform worse than the original pretrained model. In 50, we find that not all layers are equally receptive to the adaptation, and the layers with the most misaligned gradients often cause performance degradation. To address this, we propose GALA, a novel layer selection criterion to identify the most beneficial updates to perform during test time adaptation. This criterion can also filter out unreliable samples with noisy gradients. Its simplicity allows seamless integration with existing TTA loss functions, thereby preventing degradation and focusing adaptation on the most trainable layers. This approach also helps to regularize adaptation to preserve the pretrained features, which are crucial for handling unseen domains. Through extensive experiments, we demonstrate that the proposed layer selection framework improves the performance of existing TTA approaches across multiple datasets, domain shifts, model architectures, and TTA losses.
7.4 Learning with heterogeneous and corrupted data
7.4.1 Towards a fully automated underwater census for fish assemblages in the Mediterranean Sea
Participants: Kilian Bürgi, Charles Bouveyron, Diane Lingrand, Frédéric Precioso.
Keywords: Diver operated video, Automated UVC, Deep learning, Object detection, Marine biology, Marine protected areas
Collaborations: Cecile Sabourault, Benoit Derijard
In marine biology and ecology, the collection of data relies mostly on diver operations, which is labor-intensive and financially costly to operate, leading to reduced frequencies of data collection missions. Technological advances in the past decade have made it available for unmanned robots to collect data, which resulted in numerous amounts of videos that need to be manually evaluated and analyzed, which created a new bottleneck. In this study 15, we explored the possibilities and differences between a manual and automated analysis of collected videos by divers simulating a remotely operated vehicle (ROV). We discuss the difference between collecting data by diver and by videos and found that both methods added species to the overall species pool and that the automation was successful. This proof of concept will be used in future studies to fasten the process of data analysis and allow more frequent data collections creating more robust data for ecological decision making.
7.4.2 Automated Counting of Fish in Diver Operated Videos (DOV) for Biodiversity Assessments
Participants: Kilian Bürgi, Charles Bouveyron, Diane Lingrand, Frédéric Precioso.
Keywords: Underwater video, Fish count prediction, Temporal convolutional network, Object detection, Marine biology, Marine conservation
Collaborations: Cecile Sabourault, Benoit Derijard
Counting fish in moving underwater videos relies on labor-intensive manual counting or imprecise metrics from stationary cameras, while there is a great potential to use better methods to receive a better fish count. For this purpose, we explored traditional methods of counting fish as well as introduced three new methods to count fish from computer vision derived data (single frame detections). This resulted in a holistic and fully automated pipeline for fish abundance extraction 63. The following different methods are proposed on transect data of three Mediterranean species with different ecological niches: 1) traditional N, 2) 1d k-means clustering method, 3) an intuitive clustering approach N and 4) a Temporal Convolutional Neural Networks (TCN) counting method. Our results show evidence of underestimation by the traditional N while the other methods showed better overall results with the proposed N and TCN methods best representing the reality. With an absolute variation comparable to inter-observer variation, we demonstrated reliable methods for quantifying fish counts.
7.4.3 Topological data analysis and multiple kernel learning for species identification of modern and archaeological small ruminants
Participants: Marco Corneli, Davide Adamo.
Keywords: Shape Analysis, Point Clouds, Classification, Multiple Kernel Learning, Topological Data Analysis
Collaborations: Manon Vuillien, Emmanuelle Vila, Agraw Amane, Thierry Argant, et al
The faunal remains from numerous Holocene archaeological sites across southwest Asia frequently include the bones of several wild and domestic ungulates, such as sheep, goats, ibexes, roe deer and gazelles. These assemblages may provide insight into hunting and animal husbandry strategies and offer paleoecological information on ancient human societies. However, the skeletons of these taxa are highly similar in appearance, which presents a challenge for accurate identification based on their bones. This paper 37 presents a case study to test the potential of topological data analysis (TDA) and multiple kernel learning (MKL) for inter-specific identification of 150 3D astragali belonging to modern and archaeological specimens. The joint application of TDA and MKL demonstrated remarkable efficacy in accurately identifying wild species, with a correct identification rate of approximately 90%. In contrast, the identification of domestic species exhibited a lower success rate, at approximately 60%. The misidentification of sheep and goat species is attributed to the morphological variability of domestic breeds. Moreover, while these methods assist in clearly identifying wild taxa from one another, they also highlight their morphological diversity. In this context, TDA and MKL could be invaluable for investigating intra-specific variability in domestic and wild animals. These methods offer a means of expanding our understanding of past domestic animal selection practices and techniques. They also facilitate an investigation into the morphological evolution of wild animal populations over time (see Fig. 7).
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The figure shows two bone point clouds along with a persistence plot of deaths vs births of topological structures. Most points lie on the same diagonal.
7.4.4 A Bayesian approach for clustering and exact finite-sample model selection in longitudinal data mixtures
Participants: Marco Corneli.
Keywords: Clustering, Longitudinal Data, Mixture Models, Bayesian Model Selection
Collaborations: Elena Erosheva, Marco Lorenzi, Xunlei Qian
In 16, we consider mixtures of longitudinal trajectories, where one trajectory contains measurements over time of the variable of interest for one individual and each individual belongs to one cluster. The number of clusters as well as individual cluster memberships are unknown and must be inferred. We propose an original Bayesian clustering framework that allows us to obtain an exact finite-sample model selection criterion for selecting the number of clusters. Our finite-sample approach is more flexible and parsimonious than asymptotic alternatives such as Bayesian information criterion or integrated classification likelihood criterion in the choice of the number of clusters. Moreover, our approach has other desirable qualities: (i) it keeps the computational effort of the clustering algorithm under control and (ii) it generalizes to several families of regression mixture models, from linear to purely non-parametric. We test our method on simulated datasets as well as on a real world dataset from the Alzheimer’s disease neuroimaging initative database.
7.4.5 Leveraging Concept Annotations for Trustworthy Multimodal Video Interpretation through Modality Specialization
Participants: Elisa Ancarani, Julie Tores, Rémy Sun, Frédéric Precioso.
Keywords: Deep Learning, Multimedia, Scene understanding, Concepts, Multimodality
Collaborations: Lucille Sassatelli, Hui-Yin Wu
Multimodal datasets usually come as multimodal data annotated for a certain construct (such as depression). However, for such tasks of video interpretation, models must not only make accurate predictions, but make them for the right reasons. Ensuring model trustworthiness is however hampered by the lack of per-modality information. We consider in 44 the case of a recently introduced dataset for the video interpretation task of detecting objectification, annotated for this end task along with multimodal explanatory concepts that provide per-modality labels (see Fig. 8). With such additional knowledge, we study how to design models with both high task accuracy and modality trustworthiness. We first introduce the MSpecF framework articulating and fusing a spectrum of variably specialized models, and two trustworthiness metrics. We show that modality-specialized models generally maximize trustworthiness, and maximize task accuracy for confident modalities. For less certain modalities, task accuracy is maximized by non-specialized models. We show that the full fusion of specialized models MSpecF(All*) achieves advantageous trade-offs between task accuracy and trustworthiness compared to other fusion choices. This work shows that rich per-modality annotations of moderate-size datasets allow to make more trustworthy models, essential for applications such as supporting social scientists in analyzing complex social constructs.
The image depicts a scene from a video with four frames showing a person sitting and then standing up, alongside transcribed speech and a checklist of elements such as type of shot, look, emotion, activities, and more. There's an analysis of different models (Visual, VT, and Text) and their predictions, with corresponding graphs showing task accuracy versus untrustworthiness. The visual model seems to be more accurate compared to the VT and Text models.
7.4.6 CleverFish: An AI-driven Platform to Monitor and Explore Marine Ecological Resources.
Participants: Killian Bürgi, Diane Lingrand, Rémy Sun, Charles Bouveyron.
Keywords: Deep Learning, Ecology, Object Dectection, Counting
Collaborations: Stéphane Petiot, Cécile Sabourault, Benoit Derijard
The crucial need for reliable, robust and un-biased biodiversity data in support of initiatives such as the 30x30 initiative, which aims to conserve 30% of the world's oceans by 2030, presents significant scientific and technological challenges. There have been advances made to automate fish biodiversity assessments using computer vision. However, the stark difference in research fields between ecology and artificial intelligence hinders the efficient use of computer vision tools for ecological tasks. 45 presents Clever-Fish, a novel tool designed to bridge the gap between artificial intelligence and marine biology (see Fig. 9). CleverFish tackles three core challenges of an efficient management tool: i) providing an easy-to-use graphical user interface to an AI pipeline, ii) accommodating global and video-specific in-app biodiversity assessment and iii) allowing fast and efficient extraction of temporal and spatial fish species distribution in a format understandable for ecologists. An accessible web application enables seamless integration into marine monitoring pipelines and conservation efforts. constructs.
The image illustrates a process for analyzing underwater biodiversity from video recordings. Users upload videos of marine environments. Software identifies and labels species within the videos, providing a frequency of occurrence graph. Results can be exported to CSV for further biodiversity assessments. The workflow involves uploading, analyzing, and exporting the data.
7.4.7 WolBanking77: Wolof Banking Speech Intent Classification Dataset.
Participants: Abdou Karim Kandji, Frédéric Precioso.
Keywords: Deep Learning, Natural Language Processing, Dataset, Wolof
Collaborations: Cheikh Ba, Samba Ndiaye, Augustin Ndione
Intent classification models have made a significant progress in recent years. However, previous studies primarily focus on high-resource language datasets, which results in a gap for low-resource languages and for regions with high rates of illiteracy, where languages are more spoken than read or written. This is the case in Senegal, for example, where Wolof is spoken by around 90% of the population, while the national illiteracy rate remains at 42%. Wolof is actually spoken by more than 10 million people in West African region. To address these limitations, we introduce in 48 the Wolof Banking Speech Intent Classification Dataset (WolBanking77), for academic research in intent classification. WolBanking77 currently contains 9,791 text sentences in the banking domain and more than 4 hours of spoken sentences. Experiments on various baselines are conducted in this work, including text and voice state-of-the-art models. The results are very promising on this current dataset. In addition, this paper presents an in-depth examination of the dataset's contents. We report baseline F1-scores and word error rates metrics respectively on Natural Language Processing (NLP) and Automatic Speech Recognition (ASR) models trained on WolBanking77 dataset and also comparisons between models.
7.4.8 Incorporating FATES Principles in Continuous Development of ML-Integrated Systems: Importance of Requirements.
Participants: Nicolas Lacroix, Frédéric Precioso.
Keywords: Deep Learning, MLOps, FATES
Collaborations: Jean-Michel Bruel, Tristan Gouaichault, Olivier Teste, Mireille Blay-Fornarino, Sébastien Mosser
The MLOps movement adopts the DevOps objective of reducing the gap between development and operations teams by integrating data scientist teams and Machine Learning (ML) models. In 53, the initial FATES-MLOps project aims to apply and adapt good software engineering practices to enhance both the quality of the ML model construction processes and the software systems produced, particularly with regard to extra-functional properties that will be critical issues: Fairness, Accountability, Transparency, Ethics, and Security (FATES). This paper focuses specifically on the formalization, measurement, and management of these properties throughout the MLOps process.
7.4.9 Leveraging multimodal explanatory annotations for video interpretation with Modality Specific Dataset
Participants: Elisa Ancarani, Julie Tores, Rémy Sun, Frédéric Precioso.
Keywords: Deep Learning, Multimedia, Scene understanding, Concepts, Multimodality
Collaborations: Lucille Sassatelli, Hui-Yin Wu
In 61, we examine the impact of concept-informed supervision on multimodal video interpretation models using MOByGaze, a dataset containing human-annotated explanatory concepts. We introduce Concept Modality Specific Datasets (CMSDs), which consist of data subsets categorized by the modality (visual, textual, or audio) of annotated concepts. Models trained on CMSDs outperform those using traditional legacy training in both early and late fusion approaches. Notably, this approach enables late fusion models to achieve performance close to that of early fusion models. These findings underscore the importance of modality-specific annotations in developing robust, self-explainable video models and contribute to advancing interpretable multimodal learning in complex video analysis.
7.4.10 Using Small Language Models to Reverse-Engineer Machine Learning Pipelines Structures
Participants: Nicolas Lacroix, Frédéric Precioso.
Keywords: Deep Learning, MLOps, FATES
Collaborations: Mireille Blay-Fornarino, Sébastien Mosser
Extracting the stages that structure Machine Learning (ML) pipelines from source code is key for gaining a deeper understanding of data science practices. However, the diversity caused by the constant evolution of the ML ecosystem (e.g., algorithms, libraries, datasets) makes this task challenging. Existing approaches either depend on non-scalable, manual labeling, or on ML classifiers that do not properly support the diversity of the domain. These limitations highlight the need for more flexible and reliable solutions. In 70, we evaluate whether Small Language Models (SLMs) can leverage their code understanding and classification abilities to address these limitations, and subsequently how they can advance our understanding of data science practices. We conduct a confirmatory study based on two reference works selected for their relevance regarding current state-of-the-art's limitations. First, we compare several SLMs using Cochran's Q test. The best-performing model is then evaluated against the reference studies using two distinct McNemar's tests. We further analyze how variations in taxonomy definitions affect performance through an additional Cochran's Q test. Finally, a goodness-of-fit analysis is conducted using Pearson's chi-squared tests to compare our insights on data science practices with those from prior studies.
8 Bilateral contracts and grants with industry
8.1 Bilateral contracts with industry
The team is particularly active in the development of research contracts with private companies. The following contracts were active during 2025:
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Participants: Pierre-Alexandre Mattei.
Naval Group: The goal of this project was the development of an open-source Python library for semi-supervised learning, via the hiring of a research engineer, Lucas Boiteau. External participants: Alexandre Gensse, Quentin Oliveau (Naval Group). Amount: 125k€. The contract ended in March 2025
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Participants: Pierre-Alexandre Mattei.
Pulse Audition: This contract was the fruit of the "start it up" program of the 3IA Côte d'Azur. The goal is to work on semi-supervised learning for hearing glasses. A research engineer (Léonie Borne) was recruited via the "start it up" program. Amount: 15 000€. The contract ended in August 2025.
8.2 Bilateral grants with industry
The team is also active in the development of research projects with private companies.
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France 2030 Project, « Accélération des usages de l’IA générative », BPI Grant
Participants: Frederic Precioso, Remy Sun, Diane Lingrand.
The project Logie IA aims both (i) at creating a value chain for interactive generative AI in social logistics robotics and beyond, demonstrated by an optimized Large Language Model (LLM) on a robot and a dedicated processor with advanced voice control, and (ii) at creating an open source sandbox that complies with European laws to help build an open source community. The consortium is composed of Enchanted Tools (Leader), Inria Maasai, Sorbonne Université ISIR, Avignon Université, NXP. Hugging Face is a non-funded partner of the consortium. Grant amount: 3.7M€ overall, 378k€ for Maasai.
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BPI Grant for the project C02PILOT
Participants: Pierre-Alexandre Mattei.
The project CO2PILOT aspires to create the go-to solution for reliable CO₂ emissions monitoring and data analysis for industrial sites. The consortium is composed of QAIrbon (Leader), Inria Maasai, APAVE, ACRI-ST, and the Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS). Grant amount: 233k€ for Maasai.
9 Partnerships and cooperations
9.1 International initiatives
The Maasai team has informal relationships with the following international teams:
- School of Mathematics and Statistics, University College Dublin (Ireland) through the collaborations with Brendan Murphy, Riccardo Rastelli and Michael Fop,
- Université Laval, Québec (Canada) through the Research Program DEEL (DEpendable and Explainable Learning) with Christian Gagné, and through Arnaud Droit,
- DTU Compute, Technical University of Denmark, Copenhagen (Denmark), through collaborations with Jes Frellsen and his team (including the co-supervision of a PhD student in Denmark: Hugo Sénétaire, who defended in 2025),
- Department of Statistics of the University of Washington, Seattle (USA) through collaborations with Elena Erosheva and Adrian Raftery,
- SAILAB team at Università di Siena, Siena (Italy) through collaborations with Marco Gori.
9.2 International research visitors
9.2.1 Visits of international scientists
Inria International Chair
- Pr. Arnaud Droit, Université Laval, Canada (Inria Int. Chair)
Other international visits to the team
- Jes Frellsen (Technical University of Denmark) and Jakub Tomczak (Chan Zuckerberg Initiative) visited the team while co-organizing GeMSS/Statlearn 2025 spring school, held at Inria in April 2025.
- Antonio Canale (University of Padova) visited the team in May 2025.
9.2.2 Visits to international teams
Research stays abroad
- Mariam Grigoryan has stayed for 3 months as a visiting scholar the Broad Institute of MIT and Harvard in March-July 2025.
- Pierre-Alexandre Mattei did three week-long visits to Jes Frellsen's team at DTU.
- Frederic Precioso has visited the team of Christian Gagné at Université Laval, Québec, Canada, in November 2025.
9.3 National initiatives
IA Cluster "Institut 3IA Côte d'Azur"
Participants: Charles Bouveyron, Pierre-Alexandre Mattei, Vincent Vandewalle.
Following the call of President Macron to found several national institutes in AI, we presented in front of an international jury our project for the Institut 3IA Côte d'Azur in April 2019. The project was selected for funding (50 M€ for the first 4 years, including 16 M€ from the PIA program) and started in September 2019. Charles Bouveyron are two of the 29 3IA chairs which were selected ab initio by the international jury and Pierre-Alexandre Mattei was awarded a 3IA chair in 2021, and Vincent Vandewalle in 2022. Charles Bouveyron was the Director of the institute since January 2021 until October 2025, after being the Deputy Scientific Director on 2019-2020. The research of the institute is organized around 4 thematic axes: Core elements of AI, Computational Medicine, AI for Biology and Smart territories. The Maasai reserch team is totally aligned with the first axis of the Institut 3IA Côte d'Azur and also contributes to the 3 other axes through applied collaborations. The team has several Ph.D. students and postdocs who are directly funded by the institute. The institute was renewed in 2024 for an additional period of 5 years, under the IA Cluster label.
Web site: 3ia.univ-cotedazur.eu
ANR Project MultiTrans
Participants: Diane Lingrand, Frederic Precioso, Remy Sun.
Partners:
- Valeo.ai
- INSA Rouen
In the MultiTrans project, we propose to tackle autonomous driving algorithms development and deployment jointly. The idea is to enable data, experience and knowledge to be transferable across the different systems (simulation, robotic models, and real-word cars), thus potentially accelerating the rate at which an embedded intelligent system can gradually learn to operate at each deployment stage. Existing autonomous vehicles are able to learn how to react and operate in known domains autonomously but research is needed to help these systems during the perception stage, allowing them to be operational and safer in a wider range of situations. MultiTrans proposes to address this issue by developing an intermediate environment that allows to deploy algorithms in a physical world model, by re-creating more realistic use cases that would contribute to a better and faster transfer of perception algorithms to and from a real autonomous vehicle test-bed and between multiple domains.
Web site: anr-multitrans.github.io
ANR Project FATE-MLOps
Participants: Frederic Precioso.
Partners:
- IRIT Toulouse
- I3S Sophia Antipolis
- McMaster, Ontario, Canada
The MLOps movement adopts the DevOps objective of reducing the gaps between development and operations teams by integrating data scientist teams and Machine Learning (ML) models. In this project, we wish to apply and adapt good software engineering practices to strengthen both the overall quality of the ML model construction processes and the quality of the software systems produced, particularly in terms of extra-functional properties that will become crucial issues: Fairness, Accountability, Transparency, Ethics, and Security (FATES). The key concerns will tackle the study, formalization, measurement, and management of these properties throughout the continuous MLOps process. Indeed, more than traditional Key Performance Indicators (KPIs), such as precision and recall, are required to evaluate models' robustness in practical applications. Our project aims to study the FATES properties and, by refining proven software engineering concepts and tools, propose a systematic and tailored approach for considering those properties, particularly from the lens of ML Scientists or ML Engineers, throughout the lifecycle of the software developed following an MLOps approach.
Web site: fates-mlops.org
ANR Project PROFILE
Participants: Frederic Precioso.
Partners:
- INRIA Lille
- I3S Sophia Antipolis
In this project, we adopt a Software Engineering (SE) approach to the problem of characterizing ML workflows from notebooks to a level of abstraction which allows code checking and code sharing. We propose to link model engineering (MDE, here “model” in the SE sense) and statistical and static analyses to characterize these ML workflows by models (also in the SE sense), which we now call PROFILES hereafter.
More specifically, our project aims to explore three complementary questions: (Q1) What information can and should be automatically extracted from a Notebook to build a profile for its analysis? (Q2) Is it possible to systematically identify typical errors from the profile (for example, the use of functions unsuited to the problem at hand) and to identify bad practices (for example, the use of test data for training)? (Q3) Can we exploit the profusion of Notebooks to accelerate ML research by encouraging, on the basis of extracted PROFILES, a pooling of knowledge and the elicitation of new good/bad practices? It is important to note that in this project, we are talking about verifying quality rules in the way a code linter would, and not in the sense of formally verifying properties.
ANR PEPR NumpEX project HPC-Sage
Participants: Diane Lingrand, Remy Sun, Pierre-Alexandre Mattei, Frederic Precioso.
Partners:
- Université de Strasbourg (UniStra)
- Inria Callisto (Sophia), Acumes (Sophia) and Makutu (Pau)
The SAGE-HPC project aims to develop a scalable, open, and interoperable software platform for multi-fidelity optimization of complex physical problems covering exascale in high-performance computing (HPC) environments. Solving this type of optimization problem represents a major scientific challenge due to the complexity of the physical phenomena modeled and the computational cost associated with high-fidelity simulations. To overcome this difficulty, the project relies both on the coordinated use of variable fidelity models—where simplified, low-cost models guide the exploration of the solution space, and high-fidelity models are used in a targeted manner to refine the results — and on the massive exploitation of exascale HPC resources, enabling the parallel processing of these approaches on a large scale.
More specifically, we propose to tackle this question through the study of deep learning techniques for these exascale problems and the collection of meta-learning insights on the process of training neural networks across different types of physical problems.
9.4 Regional initiatives
Centre de pharmacovigilance, CHU Nice
Participants: Charles Bouveyron, Alexandre Destere, Marco Corneli, Michel Riveill.
Collaborators: Milou-Daniel Drici
The team works very closely with the Regional Pharmacovigilance Center of the University Hospital Center of Nice (CHU) through several projects. The first project focuses on the construction of a dashboard to classify spontaneous patient and professional reports, but above all to report temporal breaks. To this end, we are studying the use of dynamic co-classification techniques to both detect significant ADR patterns and identify temporal breaks in the dynamics of the phenomenon. The second project focuses on the analysis of medical reports in order to extract, when present, the adverse events for characterization. After studying a supervised approach, we are studying techniques requiring fewer annotations.
10 Dissemination
10.1 Promoting scientific activities
10.1.1 Scientific events: organization
- Charles Bouveyron , Marco Corneli , Pierre-Alexandre Mattei , Remy Sun , and Vincent Vandewalle were local organizers of the 32nd Summer Working Group on Model-Based Clustering, held at Inria in July 2025.
- Diane Lingrand and Pierre-Alexandre Mattei were part of the scientific council of the SophI.A Summit 2025. Pierre-Alexandre Mattei was head of the council.
- Charles Bouveyron , Marco Corneli , and Pierre-Alexandre Mattei were co-organizers of the GeMSS/Statlearn 2025 spring school, held at Inria in April 2025.
- Pierre-Alexandre Mattei was a co-organizer of the workshop GenU 2025.
- Pierre-Alexandre Mattei was a co-organizer of a joint day of seminars between the Probability and Statistics team from the LJAD and Maasai.
- Pierre-Alexandre Mattei was a co-organizer of the first edition of EurIPS.
- Frederic Precioso , Remy Sun and Diane Lingrand were organizers of the Deep Learning School held at SophiaTech in June and July 2025.
10.1.2 Scientific events: selection
- Pierre-Alexandre Mattei is an area chair for the conferences NeurIPS and ICML.
- Most members of the team regularly review papers for major ML/CV conferences.
10.1.3 Journal
- Charles Bouveyron is associate editor of the Annals of Applied Statistics
- Most members of the team regularly review papers for ML/CV/stats journals.
10.1.4 Invited talks
- Frederic Precioso has delivered a talk at the RENDEZ-VOUS IA QUÉBEC 2025, Quebec, Canada, in November 2025.
- Charles Bouveyron has delivered a keynote talk at the 7th International Conference on Statistics: Theory and Applications, Paris, France, in August 2025.
- Pierre-Alexandre Mattei has delivered a keynote talk at the 56th Journées de Statistique of the French Statistical Society, in Marseille, in June 2025.
- Pierre-Alexandre Mattei gave an invited talk at the GAIA Seminar jointly organized by the GIPSA-lab and the DATA department of the LJK in Grenoble, in January 2025.
10.1.5 Leadership within the scientific community
- Charles Bouveyron has been the Director of the Institut 3IA Côte d'Azur from January 2021 to October 2025.
- Vincent Vandewalle is the Deputy Scientific director of the EFELIA Côte d'Azur education program since September 2022.
10.1.6 Scientific expertise
- Charles Bouveyron is member of the Scientific Orientation Council of Centre Antoine Lacassagne, Unicancer center of Nice.
10.1.7 Research administration
- Charles Bouveyron administered the Institut 3IA Côte d'Azur as director (20 M€ per 5 years).
10.2 Teaching - Supervision - Juries - Educational and pedagogical outreach
10.2.1 Supervision
The team has 5 senior researchers with HDR that are able to supervise Ph.D. students. Usually, the supervision of the Ph.D. students of the team is jointly made by a senior and a junior researchers of the team. The following Maasai PhD students defended in 2025:
- Hugo Senetaire (co-supervised by Pierre-Alexandre Mattei and Jes Frellsen) defended in May 2025, at the Technical University of Denmark. The committee was composed of Georgios Arvanitidis, Lars Kai Hansen, Thomas Schön, and Samek Wojciech.
- Kilian Burgi (co-supervised by Charles Bouveyron and Cécile Sabourault), Detection and monitoring of marine biodiversity by artificial intelligence.
10.2.2 Juries
All senior members of the team are actively involved in the supervision of postdocs, Ph.D. students, interns and participate frequently to Ph.D. and HDR defenses.
10.3 Popularization
- Charles Bouveyron , Kilian Burgi, Remy Sun and Diane Lingrand have released the web platform CleverFish allowing to bridge the gap between marine biology and AI. CleverFish tackles three core challenges of an efficient management tool: providing an easy-to-use graphical user interface. accommodating global and video-specific in app biodiversity assessment. allowing fast and efficient extraction of temporal and spatial fish species distribution in a format understandable for ecologists.
- Charles Bouveyron , Frederic Precioso and Vincent Vandewalle participated in a series of TV documentaries on Artificial Intelligence for TV Monaco and TV5 Monde.
- Frederic Precioso gave a full day tutorial on "Building your own LLM from Scratch" (part1 & part2).
- Pierre-Alexandre Mattei gave an interview to Nice-Matin to promote the SophI.A Summit 2025.
11 Scientific production
11.1 Major publications
- 1 inproceedingsAn in depth look at the Procrustes-Wasserstein distance: properties and barycenters.PMLRForty-Second International Conference on Machine Learning (ICML, 2025)267Vancouver (CA), Canada2025, 444-459HAL
- 2 articleClustering of recurrent events data.Journal of Applied Statistics5211January 2025, 2031 - 2059HALDOI
- 3 articleThe Deep Latent Position Topic Model for Clustering and Representation of Networks with Textual Edges.Scandinavian Journal of Statistics5242025, 1975-2013HALDOI
- 4 articleTowards a fully automated underwater census for fish assemblages in the Mediterranean Sea.Ecological Informatics85March 2025, 102959HALDOI
- 5 inproceedingsMerging Embedded Topics with Optimal Transport for Online Topic Modeling on Data Streams.Joint European Conference on Machine Learning and Knowledge Discovery in Databases16019Lecture Notes in Computer SciencePorto, PortugalSpringer Nature SwitzerlandSeptember 2025, 290-307HALDOI
- 6 inproceedingsWolBanking77: Wolof Banking Speech Intent Classification Dataset.NeurIPS 2025 - 39th Conference on Neural Information Processing SystemsSan Diego (Californie - EU), United StatesDecember 2025HAL
- 7 articleAre Ensembles Getting Better all the Time?Journal of Machine Learning Research26201September 2025, 1-56HAL
- 8 articleA Tutorial on Discriminative Clustering and Mutual Information.ACM Computing Surveys584October 2025, 1-36HALDOI
- 9 inproceedingsA Layer Selection Approach to Test Time Adaptation.AAAI'25/IAAI'25/EAAI'25: Proceedings of the Thirty-Ninth AAAI Conference on Artificial Intelligence and Thirty-Seventh Conference on Innovative Applications of Artificial Intelligence and Fifteenth Symposium on Educational Advances in Artificial IntelligenceThirty-Ninth AAAI Conference on Artificial Intelligence3919Philadelphia, Pennsylvania, United StatesApril 2025, 20237-20245HALDOI
- 10 inproceedingsMind the map! Accounting for existing maps when estimating online HDMaps from sensors..Winter conference on Applications of Computer Vision - WACV 2025Tucson (USA), United States2025HALDOI
- 11 inproceedingsRe-examining Concept-based Explainable Models for Multimodal Interpretative Tasks.MM '25: Proceedings of the 33rd ACM International Conference on MultimediaPages 12437 - 12445MM 2025 - 33rd ACM International Conference on MultimediaDublin, IrelandACMOctober 2025, 12437-12445HALDOI
11.2 Publications of the year
International journals
Invited conferences
International peer-reviewed conferences
Conferences without proceedings
Scientific book chapters
Edition (books, proceedings, special issue of a journal)
Reports & preprints
Other scientific publications