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Comment pratique-t-on l’ouverture : usages et parcours en mutation ?
No full textInternational audienc
A Modular Triple Exchange Co-learning Framework for Anomaly Detection in Scarcely Labeled Graph Data
No full textInternational audienceGraph anomaly detection (GAD) is a fundamental task in numerous real-world applications, including fraud detection, network security, and financial risk assessment. However, existing approaches struggle with label scarcity, limiting the effectiveness of purely supervised and semi-supervised models. Co-training frameworks have demonstrated improvements through collaborative learning, but they remain constrained by their rigid structure and reliance on graph-specific architectures.In this paper, we introduce TExGAD, a novel collaborative learning framework that extends co-training by introducing a modular triple-exchange mechanism that leverages three detectors: (1) a flexible Semi-supervised Detector, allowing for the integration of both shallow and non-graph-specific models, (2) an Unsupervised Detector that identifies structural deviations in the graph without relying on labeled data, making it particularly effective at detecting normal nodes and scattered anomalies, and (3) a Deep Detector that captures richer anomaly representations by leveraging high-confidence predictions from the other detectors. Furthermore, TExGAD integrates a set of specialized loss functions, ensuring a balance between diversity, alignment, and independent learning and an adaptive scoring function that further refines anomaly detection by dynamically weighting detector contributions based on their confidence. Our experiments demonstrate the effectiveness of TExGAD in low-label environments, highlighting its adaptability and robustness
Representative Policy-Makers? A Behavioral Experiment with French Politicians
No full textThis study leverages an online behavioral experiment to analyze whether politicians’ decisions align with citizens’ preferences over the same issue and whether their decisions align with citizens' decisions within the same decision environment. We recruited 760 local politicians and 655 non-politicians in France to participate as policy-makers in a taxation-redistribution game. In the game, two policy-makers compete to choose a flat tax rate for a group of citizens, who are selected from the French general population and state their preferred tax rate. We exogenously manipulate (i) the information provided to policy-makers about citizens’ preferred tax rates and (ii) the degree of competition between policy-makers. Finally, we measure policy-makers' beliefs regarding citizens' preferences. We observe that policy-makers positively react to the information, but they often deviate from it, which can be mostly explained by their beliefs. Varying the degree of political competition has no impact on these results. Finally, we find that politicians believe citizens want lower tax rates and are more confident in their beliefs than non-politicians. Once beliefs are accounted for, we observe little differences between the two samples. Our findings highlight the importance of politicians' beliefs and intrinsic motivations as determinants of their decisions
La territorialisation des politiques éducatives : un chemin aux sentiers qui bifurquent ?
No full text[ Lecture ] - Aux bas-fonds, l’économie : à propos de l’ouvrage de Patrick Mardellat, Économie Radicale. Philosophie économique du don, de la richesse et de la pauvreté, Hermann, 2024, 532 pages
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Une nouvelle mission archéologique française à Erbil : coopération, patrimoine et enjeux scientifiques
No full textArchéOrient - Le Blo
Essays on microeconomics of transportation
No full textThe manuscript is organised into five sections. The first section is an introduction presenting my scientific position, my teaching activities, the management of studies, the supervision and animation of research, and finally the recent creation of the Association Française d'Economie des Transports of which I am vice-president. Sections 2, 3 and 4 present a collection of my recent contributions to transport economics research. Section 2 includes three articles analysing different manifestations and effects of congestion in public transport. The first looks at the effects of public transport congestion on user satisfaction, using a survey of stated preferences collected on the platforms of the Paris metro. The second studies the effects of congestion on users' choice of departure times. A microeconomic model is used to define the decentralised equilibrium and the social optimum, and to study the mechanisms for refocusing the social optimum. The third article examines the effects of congestion on the economies of scale of urban public transport operations. A microeconomic model is used to show that congestion phenomena (longer travel and waiting times, discomfort) appear when demand increases significantly, leading to diseconomies of scale and calling into question the subsidies granted to passengers during hyper peak periods. Section 3 contains two articles that study individual preferences for carpooling. The first article analyses these preferences for short-distance carpooling and the second for short-distance carpooling, using surveys of stated preferences collected through web-surveys. These preferences are analysed mainly by estimating the opportunity cost of travel time (or value of travel time) specific to each mode. Section 4 includes two papers that study the efficiency of regional rail services. The first studies price and frequency efficiency using a partial equilibrium model calibrated on two corridors: Ghent - Brussels in Belgium and Grenoble - Lyon in France. The second studies the productive efficiency of TER regional branches in France using a stochastic production frontier model. Finally, Section 5 presents my research perspectives in terms of method, topics and current and future projects
