Résumé
This is an application paper in which we propose to present the actualimplementation of default reasoning under conceptual graph formalism usingCoGui. CoGui is a free graph-based visual tool, developed in Java, for buildingConceptual Graph knowledge bases. We present the extension of this applicationto define and represent default CG rules (a CG-oriented subset of Reiter’s defaultlogics) and how to use these rules in skeptical or credulous reasoning.