Enhancing the selection of a model-based clustering with external qualitative variables

In cluster analysis, it can be useful to interpret the partition built from the data in the light of external categorical variables which were not directly involved to cluster the data. An approach is proposed in the model-based clustering context to select a model and a number of clusters which both fit the data well and take advantage of the potential illustrative ability of the external variables. This approach makes use of the integrated joint likelihood of the data and the partitions at hand, namely the model-based partition and the partitions associated to the external variables. It is noteworthy that each mixture model is fitted by the maximum likelihood methodology to the data, excluding the external variables which are used to select a relevant mixture model only. Numerical experiments illustrate the promising behaviour of the derived criterion

Pratique de l'heuristique de pente et le package CAPUSHE

National audienceLa mise en oeuvre des méthodes "data-driven" de calibration de critères pénalisés, issues de l'heuristique de pente de Birgé et Massart (2007), implique des difficultés pratiques

Politique Trame verte et bleue : quelle cohérence territoriale ?

International audienceThe French public policy “Trame verte et bleue” (TVB) aims at preserving and restoring ecological networks. It is implemented at different scales, from national to regional and to local. The TVB coherence between spatial and governance scales is established in the French law. But territories have a wide margin for interpretation and implementation of this policy, which is paradoxically both a source of coherence and incoherence. A balance has to be found between different territory functions and between territories, implying compromises between stakeholders who have a variety of interests. We provide a territorial coherence evaluation grid of these “social-ecological” systems. After a definition of this form of territorial coherence, we shall present and discuss the evaluation grid with its criteria, together with our preliminary results on case study areas in Bretagne and Languedoc-Roussillon (two French regions).La Trame verte et bleue (TVB) vise la préservation et la remise en bon état des continuités écologiques. Cette politique publique est multi-échelles et se décline du national au régional au local. La cohérence de la TVB entre les échelles spatiales et de gouvernance est cadrée dans la loi française. Mais une importante marge d’appréciation de la politique est laissée aux territoires, ce qui est paradoxalement à la fois source de cohérence et d’incohérence. Un équilibre est à trouver entre les différentes fonctions du territoire et entre les territoires, impliquant des compromis entre acteurs aux intérêts distincts. Nous proposons une grille d’analyse de la cohérence territoriale de ces systèmes « socio-écologiques », au coeur des projets de réseaux écologiques. Après avoir défini les contours de cette forme de cohérence territoriale multi-dimensionnelle, nous présenterons et discuterons de la grille d’analyse assortie des critères identifiés, ainsi que de nos premiers résultats sur nos territoires d’étude en Bretagne et en Languedoc-Roussillon

Slope Heuristics: Overview and Implementation

RR INRIA-7223, Version 1Model selection is a general paradigm which includes many statistical problems. One of the most fruitful and popular approaches to carry it out is the minimization of a penalized criterion. Birgé and Massart (2006) have proposed a promising data-driven method to calibrate such criteria whose penalties are known up to a multiplicative factor: the ``slope heuristics''. Theoretical works validate this heuristic method in some situations and several papers report a promising practical behavior in various frameworks. The purpose of this work is twofold. First, an introduction to the slope heuristics and an overview of the theoretical and practical results about it are presented. Second, we focus on the practical difficulties occurring for applying the slope heuristics. A new practical approach is carried out and compared to the standard dimension jump method. All the practical solutions discussed in this paper in different frameworks are implemented and brought together in a Matlab graphical user interface called capushe

The “Trame verte et bleue” French Policy: What Territorial Coherence Does it Offer?

Can the territorial coherence concept facilitate the implementation and the assessment of the French public policy called “Trame verte et bleue” (TVB)? Coherence is inherent to TVB and is expressly noted in French law. The TVB policy has to be coherent at different territorial levels, from national to local and between adjacent territories. Policy goals linked to landscape ecology concepts have to provide synergies with other territory goals: economic activity, housing, tourism... How can TVB project coherence be supported? In our work, we rely on the territorial coherence concept which we believe, has yet to be studied in the inter-scale assessment framework of public policy. In this communication, we aim to describe the territorial coherence concept and propose an analytical framework for testing this concept in our research for TVB projects

Discovering Model Transformation Pre-conditions using Automatically Generated Test Models

International audienceSpecifying a model transformation is challenging as it must be able to give a meaningful output for any input model in a possibly infinite modeling domain. Transformation preconditions constrain the input domain by rejecting input models that are not meant to be transformed by a model transformation. This paper presents a systematic approach to discover such preconditions when it is hard for a human developer to foresee complex graphs of objects that are not meant to be transformed. The approach is based on systematically generating a finite number of test models using our tool, PRAMANA to first cover the input domain based on input domain partitioning. Tracing a transformation's execution reveals why some preconditions are missing. Using a benchmark transformation from simplified UML class diagram models to RDBMS models we discover new preconditions that were not initially specified

Sélection de modèle pour la classification non supervisée

National audienceNous rappelons les bases de l'approche de la classification non supervisée par les modèles de mélange