@ARTICLE{10.21494/ISTE.OP.2018.0231, TITLE={CxG-based simulation of Group Activity}, AUTHOR={Patrick Brézillon, }, JOURNAL={Modeling and Using Context}, VOLUME={2}, NUMBER={Issue 1}, YEAR={2018}, URL={http://www.openscience.fr/CxG-based-simulation-of-Group-Activity}, DOI={10.21494/ISTE.OP.2018.0231}, ISSN={2514-5711}, ABSTRACT={The Contextual-Graph (CxG) formalism allows the representation of a task realization by an actor. The objective is to provide decision makers with a clear panorama of the different ways to realize a task (i.e. the practices), and thus of the implications of choosing one alternative or another. The Contextual-Graph formalism has been successfully used in many fields, such as medicine, biology, and transportation. In this paper, we extend the formalism to modeling group activity, and illustrate its extensions on a real-world application called the TACTIC project. The extensions concern the introduction of (1) simulation parameters for managing the interactions among the actors, (2) the notion of turn for representing a traversal of the contextual meta-graph (the model of the group activity), (3) a turn mechanism for incorporating the cyclic use of the contextual meta-graph, and (4) a CxG-based simulator for studying interaction among group members. A real understanding of group activity does not just help decision makers, but also provides real requirements for building successful applications.}}