  Our contribution concerns interactive decision support systems for group
decision support. Through this study, we apply to implement a decisional
process aiming to represent the multiplicity of actors, their diversity, their
behaviors and their interactions. In this context, we contribute to the design
and development of a group decision support system. The system is modeled by a
multi agents system while exploiting a negotiation protocol based on mediation
and concession. This protocol allows decision-makers to express their
preferences using multicriteria analysis methods, mainly the method by total
aggregation AHP (Hierarchical Process Analysis) and the method by partial
aggregation PROMETHEE II .
