MALOTEC Séminaire de MAthématique et LOgique pour l’exTraction et le traitEment de Connaissances


  • Le séminaire est organisé par le LORIA
    (CNRS – Inria Nancy G. E.- Université de Lorraine)
  • Il cherche à fomenter les échanges entre les chercheurs français et étrangers par la présentation de leurs travaux récents
  • Les manifestations des jeunes chercheurs sont bienvenues
  • Il est animé par l’équipe Orpailleur : Miguel Couceiro, Amedeo Napoli
  • Les thèmes abordés sont très variés et portent sur les sciences de l’information et  de la vie: mathématiques discrètes (théorie des graphes, des ensembles ordonnés, algèbre, combinatoire), mathématiques de la décision et de l’information (théorie de l’agrégation et du choix social, aide à la décision, théorie des jeux), logique (modélisation, représentation et raisonnement sur des connaissances) et intelligence artificielle (apprentissage artificielle, analyse de donnés, data mining)


  • Vendredi le 03 mai 2019, de 11h00 à 12h00, Salle A008 (LORIA):

Abdelkader Ouali: Pattern set mining using integer linear programming
Résumé : In this seminar, I will present a hybrid approach based on Integer Linear Programming that responds effectively to different queries of pattern set mining. The interest of this approach is illustrated by two well-known problems in data mining: conceptual clustering and tiling. Finally, I will present some perspectives on how to use constraint programming to address some multicriteria tasks in data mining.

  • Jeudi le 02 mai 2019, de 11h00 à 12h00, Salle A008 (LORIA):

Alexandre Bazin: Rules in Symbolic Data
Résumé : Rules are one way of expressing the regularities found in data. They can either be analysed by humans, in order to better understand the situation modelled by the data, or used by machines to perform inference. In this presentation, we will talk about the rules that can be found in symbolic (binary) data. We will discuss how to reduce their numbers both for human analysis (with loss of information) and for inference (without loss of information).

  • Mardi le 23 avril 2019, de 11h00 à 12h00, Salle A008 (LORIA):

Valia Mitsou: Limitation of treewidth for problems beyond NP
Résumé : In this seminar, we take a closer look at the parameterized complexity of problems belonging in and , the second level of the polynomial hierarchy. We provide tight fine-grained bounds on their complexity with respect to the most important structural graph parameter, the treewidth. We observe that these problems exhibit similar behavior: we show that a variety of diverse problems including ∃∀SAT, Choosability, as well as various problems from AI such as Abduction and Abstract Argumentation, while they admit a algorithm, they cannot be solved in time under the Exponential Time Hypothesis.

  • Jeudi le 04 avril 2019, de 14h00 à 15h00, Salle C005 (LORIA):

Lydia Boudjeloud-Assala: Human in the loop: Visual -massive and temporal- data mining
Résumé : I will present a review of my research on cooperative approaches combining interactive visualization methods and automatic methods (attribute selection, clustering, biclustering, and outlier detection) for knowledge discovery in massive and temporal data. I will present different ways to involve the user in the data mining process in order to improve his confidence and understanding of the models and their results. New challenges for these methods, which must be able to handle not only increasing amounts of data but also data that can change over time, will also be presented and discussed.

  • Mercredi le 03 avril 2019, de 11h00 à 12h00, Salle B013 (LORIA):

Samir Loudni: From Skypatterns to Skypatterns cube
Résumé : Discovering useful patterns from data is an important field in data mining for data analysis and is used in a wide range of applications. Many approaches have promoted the use of constraints to focus on the most promising knowledge according to a potential interest given by the final user. Using the dominance relation is a recent trend in constraint-based data mining to produce useful pattern sets.
The notion of skyline queries [Börzsönyi et al., 2001] has been recently integrated into the pattern discovery paradigm to mine skyline patterns (henceforth called skypatterns) [Soulet et al., 2011]. Given a set of measures, skypatterns are based on a Pareto-dominance relation for which no measure can be improved without degrading the others. Skypatterns are highly interesting since they do not require thresholds on the measures and the dominance relation gives them a global interest with a semantics easily understood by the user. In this talk, I will present a flexible and efficient approach to mine skypatterns using the constraint programming framework.
In practice, users do not know the exact role of each measure and it is difficult to select beforehand the most appropriate set of measures. Users would like to keep all potentially useful measures, look what happens on skypattern sets by removing or adding a measure, thus, evaluating the impact of measures and then converge to a convenient skypattern set. To address this issue we introduce the notion of Skypattern Cube which is the lattice of all possible measure combinations associated with their skypattern sets. By comparing two neighboring nodes (differentiated by a single measure), users can observe new skypatterns and those that die out, which greatly contributes to better understand the role of the measures.

  • Mercredi le 27 mars 2019, de 11h00 à 12h00, Salle B013 (LORIA):

Saïd Jabbour: Data mining by constraints
Résumé : In this presentation, I will address the issue of data mining by constraints. I will present some contributions on declarative approaches for different data mining tasks including frequent itemset mining and its various condensed forms, association rules, sequential pattern mining, uncertain frequent itemset mining and gradual itemset mining. To highlight the cross-fertilization between symbolic AI and data mining, I will show how linear constraints can be used to summarize large graphs, how data mining techniques can be exploited to compress Boolean formulas and finally how the concept of symmetry, widely explored in SAT/CP, is extended to pattern mining.

  • Jeudi le 28 février 2019, de 11h00 à 12h00, Salle A008 (LORIA):

Marc Plantevit : Pattern Mining in Augmented Graphs
Résumé : Graphs are a powerful mathematical abstraction that enables to depict many real world phenomena. Vertices describe entities and edges identify relations between entities. Such graphs are often augmented with additional pieces of information. For instance, the vertices or the edges are enriched with attributes describing them and are called vertex (respectively edge) attributed graphs. Graphs can also be dynamic, i.e., the structure and the values of vertex attributes may evolve through time. The discovery of patterns in such graphs may provide actionable insights and boost the user knowledge. In this talk, I will discuss the different pattern domains for augmented graphs I contributed to define. This includes the discovery of exceptional attributed subgraphs in edge or vertex attributed graphs. Then, I will discuss how to find patterns of higher interest by taking into account the domain knowledge, user feedback and user’s prior knowledge through different examples.

  • Lundi le 02 juillet 2018, de 14h00 à 15h00, Salle B013 (LORIA):

Martin Trnecka : Boolean Matrix Factorization from Formal Concept Analysis Perspective
Résumé : Boolean matrix factorization (BMF) is becoming an established method for analysis and preprocessing of data. The existing BMF methods are based on various types of heuristics because the main computational problems involved are known to be provably hard. The heuristics employed, however, use only a limited theoretical insight regarding BMF. This talk attempts to show that a better understanding of the geometry of Boolean data, provided by formal concept analysis, results in a better understanding of BMF, theoretically justified heuristics, and better algorithms.

  • Jeudi le 07 juin 2018, de 10h30 à 12h30, Salle B011 (LORIA):

10h30-11h15. Nyoman Juniarta: Sequential Pattern Mining using FCA and Pattern Structures for Analyzing Visitor Trajectories in a Museum
Résumé : The presentation is about mining visitor trajectories in Hecht Museum (Haifa, Israel), within the framework of CrossCult European Project about cultural heritage. We present a theoretical and practical research work about the characterization of visitor trajectories and the mining of these trajectories as sequences. The mining process is based on two approaches in the framework of FCA, namely the mining of subsequences without any constraint and the mining of frequent contiguous subsequences. Both approaches are based on pattern structures. In parallel, a similarity measure allows us to build a hierarchical classification which is used for interpretation and characterization of the trajectories w.r.t. four well-known visiting styles.

11h15-12h00. Tatiana Makhalova: A first study on what MDL can do for FCA
Résumé : Formal Concept Analysis can be considered as a classification engine able to build classes of objects with a description or concepts and to organize these concepts within a concept lattice. The concept lattice can be navigated for selecting significant concepts. Then the problem of finding significant concepts among the potential exponential number of concepts arises. Some measures exist that can be used for focusing on interesting concepts such as support, stability, and other. MDL (minimum description length) is also a good candidate that was rarely used in FCA by now for such objective. In this talk it will be argued that MDL can give FCA practitioners a good measure for selecting significant and representative concepts.

12h00-12h30. Quentin Brabant: Extracting Decision Rules from Qualitative Data via Sugeno Utility Functionals.
Résumé : Sugeno integrals are qualitative aggregation functions. They are used in decision making, for combining several evaluations of an alternative (with respect to different criteria, or made by several agents) into a unique value. The combination of a Sugeno integral with a « rescaling » function on each criterion is called a Sugeno utility functionals (SUF). Any SUFs can be represented by a set of multi-threshold decision rules. However, not all sets of multi-threshold rules can be represented by a single SUF. I will present functions defined as the minimum or the maximum of several SUFs. These so-called max-SUFs and min-SUFs are equivalent to sets of multi-threshold decision rules. As we will see, we can make use of these max-SUF and min-SUF as intermediary models for extracting accurate and parcimonious rule sets from empirical datasets.

  • Mardi le 22 mai 2018, de 11h00 à 12h00, Salle B013 (LORIA):

Kevin Dalleau : Unsupervised Extremely Randomized Trees
Résumé : Many unsupervised learning algorithms rely on a (dis)similarity measure to evaluate the pairwise distance between samples. Despite the large number of measures already described in the literature, in many applications, the set of available metrics is reduced by intrinsic characteristics of the data and of the chosen algorithm. In this talk, I will present a novel method based on extremely randomized trees. This method, UET (Unsupervised Extremely Randomized Trees), is based on the work of T.Shi and S.Horvath and can be generalized to heterogeneous data, enabling the clustering of datasets with mixed-types variables. The evaluation of the methods shows promising results, both in terms of discrimination of instances and in terms of running time.

  • Mardi le 17 avril 2018, de 11h00 à 12h00, Salle B013 (LORIA):

Paul Dorbec : Autour des ensembles dominants: des graphes et des jeux
Résumé : Dans cet exposé, nous partirons d’un des principaux problèmes de théorie des graphes, le problème de l’ensemble dominant. Nous évoquerons d’abord quelques questions classiques sur le problème, notamment au sujet des graphes cubiques. Nous en verrons ensuite une variante avec un phénomène de propagation, motivée par la question de la maintenance de réseaux électriques. Nous évoquerons enfin une variante ludique, ce qui devrait nous amener à évoquer succinctement la théorie des jeux combinatoires.

  • Jeudi le 12 avril 2018, de 11h00 à 12h00, Salle B013 (LORIA):

Samir Loudni : Approches déclaratives pour la fouille de données orientée motifs
Résumé : La programmation par contrainte (PPC) et la programmation linéaire en nombres entiers (PLNE) offrent un cadre générique et flexible pour résoudre des problèmes d’optimisation sous contraintes. L’utilisation de la PPC/PLNE pour exprimer des problèmes de fouille de données possède de nombreux avantages. Le premier est d’offrir à l’utilisateur un moyen simple et déclaratif pour modéliser ses problèmes. Le second est de proposer une approche générique de résolution qui permet à l’utilisateur de ne plus devoir se préoccuper de l’écriture d’un algorithme spécifique pour chaque tâche de fouille. Dans cet exposé, je vais présenter quelques contributions concernant les apports de la PPC pour la fouille de données orientée motifs et plus particulièrement sur l’extraction de motifs séquentiels et de motifs Pareto. Ensuite, je vais montrer comment la PLNE peut être exploitée pour modéliser de tâches d’optimisation en fouille de données, comme le problème du clustering conceptuel, ou encore le tiling. Enfin, je terminerai par nos travaux en cours sur la prise en compte du principe d’équité pour générer des clusterings équilibrés en utilisant des fonctions d’agrégation collectives de type OWA (Ordered Weighted Averages).

  • Mercredi le 12 mars 2018, de 11h00 à 12h00, Salle B013 (LORIA):

Yann Rivault : Le Web des données pour l’élagage et la sélection de règles d’association en pharmacovigilance
Résumé : Avec l’accroissement des données cliniques disponibles apparaissent des besoins méthodologiques pour l’aide à la décision, la prescription ou encore la surveillance. Le Web des données et les standards du web sémantique offrent des opportunités pour répondre à ces besoins. Dans le cadre d’une collaboration avec le CHRU de Nancy, nous nous intéressons à des stratégies permettant l’élagage et le classement de règles d’association. En effet, l’extraction de règles d’association voit son utilité limitée par le très grand nombre potentiel de règles extraites. Nous faisons l’hypothèse que l’apport de connaissances issues du Web des données pourrait contribuer à l’identification des règles d’association les plus pertinentes pour un système de surveillance en pharmacovigilance. Un enrichissement des données de prescriptions et des diagnostics issus de la base de données hospitalière pourrait permettre de cibler les règles d’association déjà connues des professionnels (e.g. les prescriptions indiquées pour un état de santé), ou encore de souligner les règles inattendues (e.g. les contre-indications médicamenteuses). L’objectif est ainsi de pouvoir distinguer les associations triviales des associations pertinentes. Tout d’abord nous étudions les sources de connaissances du Web des données qui pourraient permettre un élagage de règles triviales et un ciblage des règles inattendues. Enfin nous investiguons l’adaptation de mesures d’intérêt des associations dans le but d’établir un classement des règles retenues.

  • Mercredi le 14 février 2018, de 11h00 à 12h00, Salle C103 (LORIA):

Joël Legrand : TreeLSTM and cross-corpus training for extracting pharmacogenomic relationships from text
Résumé : A key aspect of machine learning algorithms for relationship extraction in textual data is the availability of sufficiently large training data. Manually annotated corpora are valuable resources for this task, but the time and expertise required for their development explains why only few annotated corpora are freely available. For tasks related to precision medicine, most of them are rather small (i.e., hundreds of sentences) or they only focus on specialized relationships (e.g., drug-drug interactions) that rarely fit what one wants to extract. In this talk, I will present two lines of research that I pursued to overcome the lack of annotated data for the task of pharmacogenomic relation extraction. I will first present a TreeLSTM-based transfer learning method that allows to achieve high performance for the extraction of biomedical relationships from text, for which initial resources are scarce. Then, I will present the PGxCorpus, a manually annotated training corpus designed for the supervised extraction of pharmaco-genomic relationships from text.

  • Mardi le 13 février 2018, de 11h00 à 12h00, Salle B013 (LORIA):

Michel Habib : Graph classes defined via vertex orderings avoiding patterns
Résumé : Consider a graph H given with a fixed ordering on its vertices. Then a graph G will belong to the class if and only if there exists an ordering of its vertices such that no subgraph of G induces a copy of H with the given fixed ordering. Let us give first a very classical example : chordal graphs. These are defined as graphs which do not contain any induced cycle of length at least 4. Is is well known (Dirac 1961) that chordal graphs are exactly graphs which admit a simplicial elimination ordering, that is an ordering on the vertices such that the neighbors of a vertex that are placed before it in the ordering induce a clique. This corresponds to the previous definition when H is the path on 3 vertices where the middle vertex is placed last in the ordering. There exists several results of this type : proper interval graphs, interval graphs, permutation graphs, co-comparability graphs, …, and it usually gives very good recognition algorithms, whereas in general forbidden subgraph characterization of a given class does not provide good algorithms.

  • Mardi le 23 janvier 2018, de 14h30 à 15h30, Salle B013 (LORIA):

Alain Gély : Distributivité d’un treillis de concepts pour les arbres phylogénétiques
Résumé : Nous nous intéressons aux treillis distributifs dans le cadre de l’analyse formelle de concepts (FCA). La motivation primitive vient de la phylogénie et des graphes médians pour représenter les dérivations biologiques et les arbres parcimonieux. La FCA propose des algorithmes efficaces de construction de treillis de concepts. Cependant, un treillis de concepts n’est pas en correspondance avec un graphe médian sauf s’il est distributif, d’où l’idée d’étudier la transformation d’un treillis de concepts en un treillis distributif. Pour ce faire, nous nous appuyons sur le théorème de représentation de Birkhoff qui nous permet de systématiser la transformation d’un contexte quelconque en un contexte de treillis de concepts distributif. Ainsi, nous pouvons bénéficier de l’algorithmique de FCA pour construire mais aussi visualiser les treillis de concepts distributifs, et enfin étudier les graphes médians associés.

  • Vendredi le 15 décembre 2017, de 11h00 à 12h00, Salle B013 (LORIA):

Tatiana Makhalova : Formal Concept Analysis: some applications in computational learning theory and machine learning
Résumé : Formal Concept Analysis and closed itemsets proved to be of big impor-tance for knowledge discovery, both as a tool for concise representation of asso- ciation rules and a tool for constructing domain taxonomies and ontologies.
In this talk, FCA will be considered in an unconventional way. We will discuss the connection of FCA with Computational Learning Theory. In particular, we will present an approach to obtaining the tight theoretical bounds of probability of overfitting and discuss why the precise bounds are not applicable in practice.The second part will be devoted to a more practical question, that is rule-based classifiers. We will see how random forests relate to frequent closed itemsets. Numerous experiments have proved that the quality of the random forests depends on such parameters as the size of bootstrap samples, the minimal size of leafs or the depth of trees as well as the size of subsets of features used to grow a tree. In the talk we will examine the question of computing a set of rules in a deterministic way in order to build an ensemble of classifiers (i.e. closed itemsets) having accuracy comparable to the random forests.

  • Mardi le 05 décembre 2017, de 14h00 à 15h00, Salle A006 (LORIA):

Emmanuel Jeandel : Computability in closure spaces
Résumé : In many instances in logic or computable algebra, classical theorems show that many problems are undecidable for general structures, but become de-cidable if some rigidity is imposed on the structure. This is the case for example for groups (the rigidity criterion is then simpleness), first order logic (complete-ness), or symbolic dynamics (minimality). We will present a topological frame-work based on closure spaces and Galois connections to show that many of these proofs can be obtained in a similar setting. We will show in particular that these statements can be generalized to cover arbitrary structures, with no finite or recursive presentation/axiomatization.

  • Mardi le 03 octobre 2017, de 11h00 à 12h00, Salle C103 (LORIA):

Jimmy Devillet : Enumerating quasitrivial semigroups
Résumé : We investigate the class of binary associative and quasitrivial operations on a given finite set. Here quasitriviality (also known as conserva-tiveness) means that the operation always outputs one of its input values. We also examine the special situations where the operations are commutative and nondecreasing. In the latter case, these operations reduce to discrete uninorms, which are discrete fuzzy connectives that play an important role in fuzzy logic. As we will see nondecreasing, associative and quasitrivial operations are chara-cterized in terms of total and weak orderings through the so-called single-peakedness property introduced in social choice theory by Duncan Black. This will enable visual interpretaions of the above mentioned algebraic properties. Motivated by these results, we will also address a number of counting issues: we enumerate all binary associative and quasitrivial operations on a given finite set as well as of those operations that are commutative, are nondecreasing, have neutral and/or annihilator elements. As we will see, these considerations lead to several, previously unknown, integer sequences.

  • Vendredi le 23 juin 2017, de 11h30 à 12h30, Salle C103 (LORIA):

Victor Codocedo : On Locality Sensitive Hashing for Sampling Extent Generators
Résumé : In this talk we introduce a method for sampling formal concepts using locality sensitive hashing (LSH). LSH is a technique used for finding approximate nearest neighbours given a set of hashing functions. Through our approach, we are able to predict the probability of an extent in the concept lattice given a set of objects and their similarity index, a generalization of the Jaccard similarity betwe- en sets. Our approach allows defining a lattice-based amplification construction to design arbitrarily discriminative sampling settings.

  • Mardi le 20 juin 2017, de 14h30 à 18h00, Salle B013 (LORIA):

14h30 – 15h00 Xavier Mazur. Clustering de séries temporelles

15h15 – 15h45 Doryan Kaced. Une approche hybride pour l’identification de biomarqueurs dans des données métabolomiques

16h00 – 16h30 Yassine Namir. D’un treillis quelconque vers un treillis distributif

16h30 – 17h00 Ilias Benjelloun. Apprentissage Relationnel Statistique :
représentation de connaissances en milieu incertain

17h00 – 17h30 Nicolas Warnet. Personnalisation d’un épisode de planification de soin : Application à la prise en charge de l’insomnie

17h30 – 18h00 Tristan Gillard. Apprentissage de connaissances d’adaptation à l’aide d’exemples positifs et négatifs

  • Mardi le 20 juin 2017, de 10h00 à 12h15, Salle B011 (LORIA):

10h00 – 10h30 Quentin Brabant. From meaningful orderings in the web of data to multi-level pattern structures

10h45 – 11h15 Justine Reynaud. A proposal for classifying the content of the web of data based on FCA and pattern structures

11h30 – 12h00 Pierre Monnin. Using FCA for checking the structure of an ontology in LOD: the example of DBpedia

  • Lundi le 12 juin 2017, de 16h00 à 17h00, Salle B013 (LORIA)

Matěj Stehlík: Topological bounds on the chromatic number
Résumé : The chromatic number is arguably the most studied invariant in graph theory. We are going to present some general upper and lower bounds on the chromatic number, before introducing a lower bound based on ideas from algebraic topology. This bound originates from Lovasz’s celebrated proof of Kneser’s conjecture in 1977. We will explore a new approach to these bounds using what we call higher-dimensional projective quadrangulations. Joint work with Tomas Kaiser.

  • Jeudi le 08 juin 2017, de 14h00 à 15h00, Salle C103 (LORIA)

Pauli Miettinen: Hyperbolic Communities: Modelling Communities Beyond Cliques
Résumé : Finding and studying communities in (social) networks is one of the key problems in (social) network analysis. Much of this research models the commu-nities as (quasi-)cliques. In recent years, there has been an increasing interest to go « beyond cliques », and consider a more varied collection of community patterns. In this talk, I will present our recent hyperbolic community model that, on the one hand, generalises the classical core-periphery community model from sociology, and on the other hand, contains graph patterns such as cliques, power-laws, and stars as special cases. The empirical evidence shows that our model fits very well to many real-world graphs, and that it also allows us to understand the shape of the communities in that graph. I will also discuss our ongoing work on finding these communities using novel methods based on tropical matrix factorisations and on our novel characterisation of nested matrices.

  • Jeudi, le 06 avril 2017, de 14h00 à 15h00, Salle: C103 (LORIA):

Lydia Boudjeloud: Approches coopératives et semi-interactives pour le traitement de données massives et temporelles
Résumé :  Je présenterai un bilan de mes travaux de recherche sur les approches coopératives combinant des méthodes interactives de visualisation et des méthodes automatiques de sélection de variables, de clustering et Bi-clustering, et de détection d’outlier pour l’extraction de connaissances à partir de données temporelles et de grande taille. Je présenterai différentes possibilités d’impliquer l’utilisateur dans le processus de fouille afin d’améliorer sa confiance et sa compréhension dans les modèles ou résultats obtenus. De nouveaux challenges pour ces méthodes, qui doivent pouvoir traiter non seulement des quantités de plus en plus importantes de données mais aussi des données qui peuvent changer dans le temps, seront également présentés et discutés.

  • Vendredi, le 23 mars 2017, de 14h00 à 15h00, Salle C103 (LORIA):

Thomas Kipf: Deep Learning on Graphs with Graph Convolutional Networks (P. 2)
Résumé : Neural networks on graphs have gained renewed interest in the machine learning community. Recent results have shown that end-to-end trainable neural network models that operate directly on graphs can challenge well-established classical approaches, such as kernel-based methods or methods that rely on graph embeddings (e.g. DeepWalk). In this talk, I will introduce two extensions to the basic framework of defining neural networks on graphs: graph auto-encoders [1] and relational graph convolutional networks (R-GCNs) [2]. While graph auto-encoders provide a new way of approaching problems like link prediction and clustering, R-GCNs allow for efficient modeling of directed, relational graphs, such as knowledge bases (e.g. DBPedia). If time permits, I will talk about some recent work that combines such graph-based approaches with deep learning methods from the field of natural language processing, to achieve new state-of-the-art results on the task of semantic role labeling.
[1] TN Kipf and M Welling, Variational Graph Auto-Encoders, NIPS Bayesian Deep Learning Workshop (2016)
[2] M Schlichtkrull, TN Kipf, P Bloem, R vd Berg, I Titov and M Welling, Modeling Relational Data with Graph Convolutional Networks, arXiv:1703.06103 (2017)

  • Mercredi, le 15 mars 2017, de 11h à 12h, Salle: B013 (LORIA):

Maria Boritchev: On Politics and Argumentation
Résumé : Argumentation mining is a relatively new topic in the field of corpus-based discourse analysis. This talk presents a work which primarily concerns with the identification of argumentative structures that can be found within dialogical discourse. Starting from data from 2016 U.S. presidential elec- tions debates, the aim is to automatically mine intertextual correspondences between political argumentation and social media reactions. Identifying the most efficient (here, reaction-rising) political discourse techniques can not only give the politicians the possibility to adjust their discourse but also give an attentive audience clues to critical thinking. During this talk I will present the current state of this work, introducing the chosen argumentation mining techniques and showing some intermediate results. Then I will finish with a discussion of the future work on intertextual correspondence mining.

  • Vendredi, le 10 mars 2017, de 14h00 à 15h00, Salle B013 (LORIA):

Jan Volec: Graph limit approach in extremal combinatorics
Résumé : In the last decade, various theories of combinatorial limits emerged, and attracted a substantial attention. In this talk, I will focus on applications of combinatorial limits and the so-called flag algebra method to problems in extremal combinatorics. I will present the main ideas behind these methods and then use them to answer a problem of Erdos on pseudo-random hypergraphs, solve a conjecture of Erdos and Sos concerned with recursive graph constructions, and to study robust versions of Turan-type problems.

  • Mercredi, le 8 mars 2017, de 11h00 à 12h00, Salle C003 (LORIA):

Abdallah Saffidine: The (Parameterized) Complexity of (Positional) Games
Résumé : Classical Computational Complexity is a popular tool from Theoretical Computer Science used to characterize the difficulty of solving decision problems. I will present how a couple intuitive criteria allow one to guess the most likely complexity class of games of various sort. We’ll then move to Parameterized Complexity which addresses some of the practical shortcomings of classical com- putational complexity and has seen increased adoption for studying graph-theoretic problems. I will describe ongoing work on building a better under- standing of the Parameterized Complexity of Games. As an application, we’ll show that Short Generalized Hex is W[1]-complete parameterized by the number of moves. This disproves a conjecture from Downey and Fellows’ influential list of open problems from 1999.

  • Vendredi, le 14 octobre 2016, de 13h à 14h, Salle: B011 & B013 (LORIA):

Joel Legrand: Word Sequence Modeling using Deep Learning
Résumé : For a long time, natural language processing (NLP) has relied on generative models with task specific and manually engineered features. Recently, the rapidly growing interest for deep learning has led to state-of-the-art results in various fields such as computer vision, speech processing and natural language processing. The central idea behind these approaches is to learn features and models simultaneously, in an end-to-end manner, and making as few assumptions as possible. In NLP, word embeddings, mapping words in a dictionary on a continuous low-dimensional vector space, have proven to be very efficient for a large variety of tasks while requiring almost no a-priori linguistic assumptions. In this talk, I will present the results of my research on continuous representations of segments of sentences for the purpose of solving NLP tasks that involve complex sentence-level relationships. I will first introduce the key concepts of deep learning for NLP. I will then focus on two recent empirical studies concerning the tasks of syntactic parsing and bilingual word alignment. For each of them, I will present the main challenges as well as the deep learning-based solutions used to overcome them.

  • Mercredi, le 5 octobre 2016, de 15h à 16h, Salle: B013 (LORIA):

François Pirot: The bounds for the distance-t chromatic number, and the effect of removing cycles
Résumé : It is well known that you can colour a graph G of maximum degree d greedily with d+1 colors. Moreover, this bound is tight, since it is reached for example by the cliques. Johansson proved with a pseudo-random colouring scheme that you can colour triangle-free graphs of maximum degree d with no more than O(d/log d) colours. This is tight up to a multiplicative constant, since you can pseudo-randomly construct a family of graphs of maximum degree d, arbitrary large girth, and chromatic number bigger than c(d/log d), for some constant c. When you introduce the distance-t chromatic number of a graph G of maximum degree d, which is simply the chromatic number of G^t, you can be interested in finding similar bounds, and proving that they are tight. It is straight-forward that d^t is an upper bound for the distance-t chromatic number, but determining how tight this bound is is far from being an easy problem. You may also wonder what happens to the bound of the distance-t chromatic number when you forbid some fixed lengths of cycles in your graph. The goal of my talk will be to give some answers to these natural questions.

  • Vendredi 3 juin 2016, de 11h à 12h00, Salle: B013 (LORIA):

Pauli Miettinen: Matrix factorization models for patterns beyond blocks
Résumé : Finding patterns, or regularities, from data and using the patterns to summarise the data are in the core of data mining. In many cases, these pattens are « block-like »: when the data can be expressed as a table of values, or as a matrix, the patterns are sub-tables (or sub-matrices) that are somehow different from the other parts of the data. Clustering, community detection, and frequent itemset mining can all be considered to find « block-like » patterns, to name a few examples. Block-like patters also fit well to the language of linear algebra, where we can model the block-like patterns as (approximate) rank-1 matrices, and data summarisations as matrix factorisations. Not all patterns or summaries in data mining are easy to express as matrix factorisations, though, and in recent years, patterns that go « beyond blocks » have become under active investigation. In this talk, I will discuss why being able to express the data mining task in matrix factorisation terms is important and cover my recent and ongoing work on different types of matrix factorisations that can be used to model patterns beyond blocks.

  • Mercredi, le 18 mai 2016, de 14h à 15h00, Salle: B013 (LORIA):

Gerasimos Meletiou: Secret Sharing Through Multivariate Birkhoff’s Interpolation
Résumé : The problem of finding secret sharing schemes with multilevel structures and partially ordered sets of levels of participants is faced. We investigate the idea of generalizing previous schemes (Shamir’s, Tassa’s) through multivariate Birkhoff’s interpolation.

  •  Jeudi, le 12 mai 2016, de 11h à 12h00, Salle: B013 (LORIA):

Sergei O. Kuznetsov: Optimizing Therapy in Subgroups of Patients with Pattern Structures
Résumé : The effectiveness of a therapy of serious lethal diseases is measured by survival curves. A therapy is better than another one if its survival curve lies strictly above. For standard randomisation strategies accepted in medical science, two therapies may be of same quality, however if we consider subgroups of patients defined by common physiological features, one treatment can be strictly better than another for certain subgroups. Closed descriptions is a very natural way for concise representation of subgroups, so we describe an efficient approach for finding closed descriptions of groups where some treatments are definitely preferred to others. The approach can be applied in other domains like optimal credit scoring.

  • Symposium Mathematics for Decision and Discovery (M4D2)

Mercredi, 11 mai 2016 (B013, LORIA): Program

  • Vendredi, le 15 avril 2016, de 14h à 15h00, Salle: B013 (LORIA):

Benjamin Momège: Autour de la connexité dans les graphes avec conflits
Résumé : Nous nous intéresserons aux graphes avec conflits (un conflit est une paire d’arêtes ne pouvant pas simultanément faire partie d’un sous-graphe), dans lesquels nous étudierons différents types de problèmes, de nature aussi bien algorithmique que combinatoire, notre ligne directrice étant la notion de connectivité. Nous verrons que plusieurs résultats, simples sans conflit, ne le sont plus lors de l’ajout de conflits. Nous présenterons : des algorithmes exacts (non polynomiaux), des résultats de NP-complétude, et des conditions suffisantes assurant l’existence de certains objets (arbre couvrant, chemin et cycle Hamiltonien) sans conflits.

  • Vendredi, le 15 avril 2016, de 11h à 12h00, Salle: B013 (LORIA):

Bruno Teheux: Automates, mots et décision
Résumé : Fonctions qui transforment les mots, les automates, les problèmes de décision. Dans ce séminaire, nous mettrons en évidence des liens entre ces diffé- rents ingrédients avec une équation très connue comme pivot: l’équation d’asso-ciativité.

  • Mardi, le 9 février 2016, de 11h30 à 12h30, Salle: B013 (LORIA):

Lucien Haddad: Partial clones and the Erdös-Faber-Lovsáz conjecture
Résumé : Let A be a finite set. A partial clone on A is a set of partial functions closed under composition and containing all projection functions on A. We survey some results in the theory of partial clones. In particular: (1) we show the link between The Erdös-Faber-Lovsáz conjecture for graphs and combinatorial descriptions of some maximal partial clones, and (2) we give a complete classification of certain intervals of partial clones, that solves an open problem by D. Lau. These results were obtained in collaboration with (1) C. Tardif and (2) M. Couceiro, K. Schölzel and T. Waldhauser.

  • Lundi, le 7 décembre 2015, de 11h30 à 12h30, Salle: B011 (LORIA):

Fabien Labernia: Conditional preferences network : an overview
Résumé : Let V be a set of binary variables. Elicitating preferences over the set of all possible assignments for V to obtain a partial (or total) order can be a very long and difficult task. Different models have been proposed to 1) help the expert to elicit these preferences (ceteris paribus preferences), 2) represent in a compact way this exponential set (conditional preference rules) and 3) catch in a formal way some preference properties (such as importance of a variable). In this presentation we will survey different models like CP-nets, TCP-nets, CP-theories and CI-nets (the different properties they catch, active learning of these models), and discuss some current research directions on these combinatorial structures.

  • Mardi, le 1 décembre 2015, de 11h à 12h00, Salle: B013 (LORIA):

Bruno Teheux: A modal logic for games with lies
Résumé : In the Rényi-Ulam game, a liar picks out a number in a given search space. A second player has to guess this number by asking Yes/No questions to the liar who is allowed to lie a maximal given number of times. It is known that states of the game can be encoded in the algebraic language using MV-algebras (which are to Łukasiewicz logic what Boolean algebras are to classical propositional logic). The aim of the talk is to present an (n+1)-valued version of Propositional Dynamic Logic (PDL) that is suitable to model the interactions between players in the Rényi-Ulam game. The ingredients of this model are modal expansions of Łukasiewicz finitely-valued logics, algebras of regular programs and many-valued Kripke models. Our main result will be a completeness result. We will also discuss the gain of expressive power allowed by the new many-valued dynamic language.

  • Mardi, le 24 novembre 2015, de 13h à 14h00, Salle: B013 (LORIA):

Kevin Dalleau: Suggesting valid pharmacogenes by mining linked data
Résumé : A standard task in pharmacogenomics research is identifying genes that may be involved in drug response variability, i.e., pharmacogenes. Because genomic experiments tended to generate many false positives, computational approaches based on the use of background knowledge have been proposed. Until now, those have used only molecular networks or the biomedical literature. Here we propose a novel method that consumes an eclectic set of linked data sources to help validating uncertain drug–gene relationships. One of the advantages relies on that linked data are implemented in a standard framework that facilitates the joint use of various sources, making easy the consideration of features of various origins. Consequently, we propose an initial selection of linked data sources relevant to pharmacogenomics. We formatted these data to train a random forest algorithm, producing a model that enables classifying drug–gene pairs as related or not, thus confirming the validity of candidate pharmacogenes. Our model achieves the performance of F-measure=0.92, on a 100 folds cross-validation. A list of top candidates is provided and their obtention is discussed.

  • Symposium on instant data mining and learning preferences for interactive data mining (PEPS Préfute + Approppre)

Jeudi, 19 Novembre 2015 (C005, LORIA): Program

Vendredi, 20 Novembre 2015 (B013, LORIA):

Victor Codocedo: When Cyberathletes Conceal Their Game: Clustering Confusion Matrices to Identify Avatar Aliases

  • Jeudi, le 1 octobre 2015, de 11h à 12h00, Salle: B013 (LORIA):

Renato Vimieiro: Mining disjunctive emerging patterns in high-dimensional data using hypergraphs
Résumé : Pattern mining is one of the most known sub-fields of data mining. Its main goal, as originally proposed by Agrawal et al., is to identify sets of attributes that are frequent amongst objects in a dataset. Most of the applications of (frequent) pattern mining involve the analysis of market basket data. In this type of data the attributes are binary and the data table is a matrix where objects are rows, attributes columns and cells indicate whether an object has an attribute. Since the beginning, the area has been extensively investigated and a wealth of efficient algorithms proposed. Although the original proposition was very successful in many domains, it was not suitable for the analysis of labelled data, i.e., data where objects had class labels. Thus one extension to frequent pattern mining, to cope with this type of data, was proposed in 1999 by Dong and Li. Their idea, named emerging patterns, was to extract patterns that were frequent amongst objects with one class label and infrequent amongst the others. Emerging patterns showed to be effective in many applications involving labelled data, particularly those in bioinformatics. In this presentation a new extension to emerging patterns will be briefly discussed. An overview of disjunctive emerging patterns will be given and an efficient algorithm based on hypergraphs and their minimal transversals for mining these patterns will be introduced.

  • Lundi, le 30 juin 2015, de 12h00 à 13h00, Salle B013 (LORIA):

12h00 – 12h30 Kenny Rivalin: Systèmes de recommandation dans le cadre de l’analyse de concepts formels

12h30 – 13h00 Benjamin Maurice: Extraction de cliques et de quasi-cliques maximales sur des graphes creux

  • Mardi, le 29 juin 2015, de 11h00 à 12h00, Salle C005 (LORIA):

Maurice Pouzet:  Boolean dimension of a graph and inversion index of a tournament
Résumé : The Boolean dimension of a graph G (undirected with no loops) is the least integer m for which there exist m subsets X1, … , Xm of the vertex set V(G) of G such that the edges of G are exactly the 2-element subsets e of V(G) which are included into an odd number of the Xi‘s. If G has n vertices, its Boolean dimension is at most n-1; it is n-1 if and only if G is a path. The inversion of a subset X of the vertex set V(T) of a tournament T consists to invert all arcs of T between two vertices of X. The inversion index of T is the least number, denoted by i(T), of subsets of V(T) to invert in order to transform T into an acyclic tournament. I will present the main results and two tantalizing problems: the value of the inversion index of paths of strong connectivity, a majoration of the size of obstructions of the class I(n) of finite tournaments whose inversion index is a most n (the fact that there is a bound follows from techniques of well quasi ordering). Results presented here originate in the thesis of H. Belkhechine [1]. They have been obtained in collaboration with H. Belkhechine, M. Bouaziz and I.Boudabbous and announced in [2].
[1] H. Belkhechine, Indécomposabilité des graphes et des tournois, thèse de doctorat, 15 juillet 2009, Université Claude-Bernard et Université de Sfax.
[2] H. Belkhechine, M. Bouaziz, I. Boudabbous, M. Pouzet, Inversion dans les tournois, C. R. Acad. Sci. Paris, Ser. I 348 (2010) 703-707.

  • Vendredi, le 5 juin 2015, de 11h00 à 12h00, Salle B013 (LORIA):

Abdallah Saffidine: Solving Games and all of that
Résumé : Efficient best-first search algorithms have been developed for deterministic two-player games with two outcomes. We present a formal framework to represent such best-first search algorithms. The framework is general enough to express popular algorithms such as Proof Number Search, Monte Carlo Tree Search, and the Product Propagation algorithm. We then show how a similar framework can be devised for two more general settings: two-player games with multiple outcomes, and the model checking problem in modal logic K. This gives rise to new Proof Number and Monte Carlo inspired search algorithms for these settings.Similarly, the alpha-beta pruning technique is known to be very important in games with sequential actions. We propose an extension of this technique for stacked-matrix games, a generalization of zero-sum perfect information two-player games that allows simultaneous moves.

  • Jeudi, le 4 juin 2015, de 11h00 à 12h00, Salle A117 (LORIA):

11h00 – 11h30. Justine Reynaud: Définition d’un langage de transformation de requêtes SPARQL

11h30 – 12h00. Quentin Brabant: Axiomatisation des intégrales de Sugeno k-maxitives

  • Mardi, le 5 mai 2015, de 14h00 à 15h00, Salle B011 (LORIA):

Erkko Lehtonen:  Homomorphisms of labeled posets
Résumé : A partially ordered set labeled with k labels (a k-poset) is a triple (P, ≤, c), where (P, ≤) is a partially ordered set and c : P → {0, …, k − 1} is a labeling function. A homomorphism of a k-poset (P, ≤, c) to another k-poset (P′, ≤′, c′) is a map h : P → P′ that preserves both the order and the labels, i.e., h(x) ≤′ h(y) whenever x ≤ y and c = c′ ⚬ h. The set of all k-posets is partially ordered by the existence of homomorphism. We present some results concerning the structure of this homomorphism order. In particular, for k ≥ 2, the homomorphism order of finite k-posets is a distributive lattice that is universal for countable posets. We also discuss the complexity of certain decision problems involving labeled posets. This talk is partly based on joint work with Léonard Kwuida.

  • Mardi, le 28 avril 2015, de 12h00 à 13h00, Salle B013 (LORIA):

Michel Grabisch:  Games on concept lattices
Résumé : We introduce cooperative TU-games on concept lattices, where a concept is a pair (S,S’) with S being a subset of players or objects, and S’ a subset of attributes. Any such game induces a game on the set of players/objects, which appears to be a TU-game whose collection of feasible coalitions is a lattice closed under intersection, and a game on the set of attributes. We investigate the geometrical properties of the core (non-emptiness, boundedness, pointedness, extremal rays). In particular, we derive the equivalence of the intent and extent core for the class of distributive concepts.