Guillaume DEFFUANT

Head of LISC (Laboratoire d'Ingénierie des Systèmes Complexes)

Cemagref
24 avenue des Landais, B.P. 50085, 63172 Aubière Cedex 1, France
Tél. : 33(0)4.73.44.06.14
E-mail : guillaume.deffuant@cemagref.fr

Research

subjects

Projects

Publications

Research subjects

Social simulation. Following the IMAGES project that I coordinated, I participated in the development of continuous opinion dynamics models. These models exhibit stylised facts which can be related to the diffusion of extreme opinions in a society.
Cognitive science in general, and more particularly the role of empathy in human cognition.
Machine Learning and Viability Theory. I am particularly interested by learning algorithms which have a natural geometric interpretation. In my thesis, I developed algorithms which build unions of polyedrons, in order to classify sets of examples. More recently, I focused on Support Vector Machines, and their application to approximate Viability kernels.

Main Projects

European project: PATRES (beginning 1st February 2007, pattern resilience)
Network of Excellence: Alter-net.
SimExplorer
European Project: Firma (Agent-based models for improving water management)
European Project: IMAGES (co-ordinator) (Diffusion of Agri-environmental measures)

Publications

Social Simulation

S. Huet, G. Deffuant, 2008, "Bounded confidence and rejection: more consensus or no clustering", presented at the International Workshop "Sociophysics: status and perspectives", 26-29 mai 2008, Turin (Italie).
S. Huet and G. Deffuant, 2008, "Bounded Confidence with Rejection: The Infinite Population Limit with Perfect Uniform Initial Density", MASHS 2008 (Modèles et Apprentissages en Sciences Humaines et Sociales), Créteil, 5-6 juin 2008.
S. Huet and G. Deffuant, 2008, "Bounded Confidence with Rejection: Clusters or Scattered Opinions?" ESSA 2008, Brescia, Italy, 11 pages.
S. Huet, G. Deffuant, and W. Jager, 2008, "Rejection Mechanism in 2D Bounded Confidence Provides More Conformity," Advances in Complex Systems, vol. 11-4, pp. 1-21, 2008.
S. Huet and G. Deffuant, 2008, "Differential equation models derived from an individual-based model can help to understand emergent effects," Journal of Artificial Societies and Social Simulation, vol. 11, pp. 21
Deffuant G., Huet S. and Skerratt S. 2008. An agent based model for agri-environmental measure diffusion: What for ?. Agent based Modelling in Natural Resource Management. pp 55-73. Universidad de Valladolid INSISOC.A. Lopez and C. Hernandez Eds
Huet, S., Edwards, M., Deffuant, G. - 2007. Taking into account the variations of neighbourhood sizes in the mean-field approximation of the threshold model on a random network. Journal of artificial societies and social simulation , vol. 10, n° 1, 15 p.
Deffuant, G., Huet, S. - 2007. Propagation effects of filtering incongruent information. Journal of business research, vol. 60, n° 8, p. 816 - 825
Huet, S., Edwards, M., Deffuant, G. - 2007. Taking into account the variations of neighbourhood sizes in the mean-field approximation of the threshold model on a random network. Journal of artificial societies and social simulation , vol. 10, n° 1, 15 p.
Deffuant G., Weisbuch G. 2007. “Probability Distribution Dynamics Explaining Agent Model Convergence to Extremism.” In Social Simulation: Technologies, Advances and New Discoveries. Idea group inc. publishing.pp 43-60
Huet, S. Deffuant G., Jager W. 2007. Rejection Mechanism in 2D bounded confidence provides more conformity. European Conference on Complex Systems. Dresden 2007.
Huet, S., Deffuant, G. - 2007. Sensitivity of primacy effect to interactions. EuroCogSci07, Delphes, Grèce ( GRC), 23-27 mai 2007. p. 830 - 835
Dubois E, Huet S., Deffuant G. 2007. Primacy Effect with Symmetric Features Propagating in a Population. ESSA Conference, Toulouse.
Mabrouk, N., Deffuant, G., Lobry, C. 2007 : Population balance versus spatially explicit modelling of flock-forming bacteria dynamics. International Conference StatPhys – Genova 2007
Mabrouk, N., Deffuant, G., Lobry, C. 2007 : Confronting macro, meso and micro scale modelling of bacteria dynamics, 3rd International conference Model-to-Model – Marseille 2007
Mabrouk, N., Deffuant, G., Lobry, C. 2007 : Individual based model of bacterial mobility in biofilms, European Conference on Conplex Systems – Dresden 2007
Deffuant G. 2006. Comparing Extremism Propagation Patterns in Continuous Opinion Models. Journal of Artificial Societies and Social Simulation vol. 9, no. 3. http://jasss.soc.surrey.ac.uk/9/3/8.html
Deffuant G. and S. Huet. 2006. Collective reinforcement of first impression bias. Proceedings of the 1^st World Conference on Social Simulation. Kyoto.
Deffuant G., S. Moss and W. Jager , 2006, Dialogues Concerning a (Possibly) New Science. Journal of Artificial Societies and Social Simulation vol. 9, no. 1
Deffuant, G., Huet, S.. & Amblard, F.,. 2005. An individual-based model of innovation diffusion mixing social value and individual benefit. American Journal of Sociology 110-4, 1041-1069.
Weisbuch, G., Deffuant, G. et Amblard, F. 2005, Persuasion dynamics“, Physica A, vol.353, p.555-575.
Amblard, F. & Deffuant, G. 2004. "The role of network topology on extremism propagation with the relative agreement opinion dynamics". Physica A Vol. 343 pp 725-738.
Deffuant, G., Amblard, F., Weisbuch, G., (2004) "Modelling group opinion shift to extreme : the smooth bounded confidence model", Proceedings of the European Social Simulation Association Conference, Valladolid, September 2004.
Deffuant, G., F. Amblard, R. Duboz et E. Ramat (2003). "Une démarche expérimentale pour la simulation individu-centrée". Journées de Rochebrune sur la complexité.
Deffuant, G., F. Amblard, G. Weisbuch et T. Faure (2003). “Simple is beautiful...and necessary.” Journal of Artificial Societies and Social Simulations 6(1).
Margaret Edwards, Sylvie Huet, François Goreaud and Guillaume Deffuant (2003). Comparing an individual-based model of behaviour diffusion with its mean field aggregate approximation. Journal of Artificial Societies and Social Simulation vol. 6, no. 4<http://jasss.soc.surrey.ac.uk/6/4/9.html>
Deffuant, G., Huet, S., Bousset, J.P., Henriot, J, Amon, G., Weisbuch, G. (2002). "Agent based simulation of organic farming conversion in Allier département". in Complexity and ecosystem management. M A. Janssen ed. Edward Elgar publishing. pp 158-187.
Deffuant, G., F. Amblard, G. Weisbuch et T. Faure (2002). “How can extremism prevail? A study based on the relative agreement interaction model.” Journal of Artificial Societies and Social Simulations 5(4).
Deffuant, G., Neau, D., Amblard, F. and Weisbuch, G., "Mixing beliefs among interacting agents", Advances in Complex Systems, 3, 87-98, 2001.
Deffuant G., Neau D., Amblard F., Weisbuch G., 2000. Evolution des croyances entre agents en interactions. Second international conference on computer simulations and the social sciences, Paris, september 2000, 2000, p. 87-98 [Publications:00/0399]
Deffuant, G., Ferrand, N., Amblard, F., Gilbert, N., and Weisbuch, G. 2000. « A model of Decision process mixing rational anticipation and social influences : example of agri-environmental measure adoption by farmers » Computational Analysis of Social & Organizational Systems International Conference, Pittsburgh (USA), July 2000.

Cognitive science and Empathy

Rousseau L. et Deffuant G. (2005). Gestion des territoires : Aider à la formulation collective des problèmes. Nature Science et Sociétés. Volume 13- Numéro 1
Deffuant, G. (2004). "S'évader du présent remémoré et construire un temps social : le rôle central de l'empathie ?". Journées de Rochebrune sur la complexité, ENST.
Deffuant G., 1998. " Les modèles cognitifs à l’épreuve des formes du religieux : proposition de directions de recherche centrées sur l’empathie ". Intellectica 1998/1-2, 26-27. pp. 89-109
Deffuant G. " L’autonomie est-elle création ou rupture d’une clôture ? tentative d'articulation entre les visions de l'autonomie de F. Varela et de C. Castoriadis". revue internationale de systémique. Vol 11, N°5, 1997, pp. 515-534.
Deffuant G., " Aller et retour de l’identité logique à l’identité empathique. Esquisse d’un cheminement possible ", Actes des journées de Rochebrune 1997, ENST.
Deffuant G., " Mécanismes empathiques et complexité sociale : autour de J.P. Dupuy ", Actes des journées de Rochebrune 1996, ENST
Deffuant G., "Adaptation et Autopoièse", Revue Ingénierie des Systèmes d'Information, Hermès, vol 1, 1993.

Machine Learning

Chapel, L., Deffuant, G., Martin, S., Mullon, C. (2008) "Defining yield policies in a viability approach". Ecological Modelling, 212 (1-2), p.10-15.
T. Faure, G. Deffuant, N. Dumoulin, F. Chuffart and R. Reullion, 2008, SimExplorer: a tool to manage the traceability and execution of simulation experiments, Grand Challenges in Modeling & Simulation, Part of Summer Simulation Multiconfernce, June 16-19, 2008, Edinburgh
B. Gandar, G. Deffuant, G. Loosli.Les suites à discrépance faible: un moyen de réduire le nombre de support vectors ?. Journées de l'école doctorale sciences pour l'ingénieur de l'université de Clermont-ferrand. 4 Juin 2008.
G. Loosli, G. Deffuant et S. Canu. 2008. BALK : Bandwidth Autosetting for SVM with Local Kernels. Application to data on incomplete grids, Cap 2008 (Conférence d'Apprentissage). Porquerolles.
Mabrouk N., Deffuant,G. "Computer simulation model of a food particle degradation in the human digestive tube"- 6th Joint INRA-RRI Symposium Clermont-Ferrand, June 18-20, 2008
Deffuant, G., Chapel, L. et Martin S. 2007. Approximating viability kernel with Support Vector Machines, IEEE transactions on automatic control. 52 (5), p.933-937.
Chapel L., Martin S., Deffuant G. 2007. Lake Eutrophication: Using resilience evaluation to compute sustainable policies. CEST 2007. Cos Island, Greece.
Alvarez, I., Bernard, S., Deffuant, G. - 2007. Keep the decision tree and estimate the class probabilities using its decision boundary. International Joint Conference of Artificial Intelligence, Hyderabad, India, 7-12 janvier 2007. 6 p.
Chapel, L., Deffuant, G., Martin, S., Mullon, C. (2005) "Defining yield policies in a viability approach". in Proceedings of the V^th European Conference on Ecological Modelling (ECEM-2005). Pushshino, Russia.
Deffuant G., Fuhs T., Monneret E., Varela F., Bourgine P., "Semi-algebraic Networks : an Attempt to Design Geometric Autopoietic Models", Artificial Life, vol 2, n°2, 1995, pp 157-177.
Deffuant G., "An algorithm for building regularized piecewise linear discrimination surfaces : the perceptron membranes", Neural Computation., vol 7, n°2, pp 380-398, 1995
Bochereau L., Bourgine P. et Deffuant G., "a General Framework for Supervised Learning : Probably Almost Bayesian Algorithms", Journal of Economic Dynamics and Control 18, pp 97-118. North-Holland, 1994
Deffuant G. et Monneret E., "Morphodynamic networks : the example of adaptive fibres", proceedings of ECAL 1993, Bruxelles 1993.
Deffuant G., "Réseaux morphodynamiques et modèles cognitifs", Actes du colloque AFCET systémique et cognition, pp 185-198, Versailles 1993.
Bourgine P. et Deffuant G., "Elicitation de l'expertise à partir d'un savoir-faire", Actes de la conférence AFIA, Compiègne 1992.
Bochereau L., Bourgine P., Deffuant G., "Réseaux connexionnistes et estimateurs bayesiens", Actes des XXIIemes journées de Statistique, Strasbourg, pp 143-146, 1991.
Bochereau L., Bourgine P., Deffuant G., "Equivalence between connectionist classifiers and logical classifiers", Lecture Notes in Physics, N°368, pp 351-364, Springer-Verlag 1990
Deffuant G., "Dualité local/global et algorithmes de recrutement", Actes de Neuro-Nîmes 1990, pp 469-479, 1990.
Deffuant G. "Neural Units recruitment Algorithms", proceedings of IJCNN 1990, San Diego, 1990.

General reports

Deffuant G., (2004). Modéliser la complexité: quelques pistes pour relever le défi. Mémoire d'Habilitation à Diriger des Recherches de l'Ecole doctorale SPI de l'université Blaise Pascal de Clermont-Ferrand.
Deffuant, G. et al. (2001). Final report of the IMAGES project: 193.
Deffuant G., (1992). Réseaux connexionnistes auto-construits, PhD Thesis, EHESS - University Paris 6.

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