Everything can be agent!

Most Multi-Agent System designers use several notions -- like "agent", "artifact", "object", etc. -- to classify the entities involved in simulations. These notions require different methodologies, data structures and algorithms. In this paper, we show that the representation of entities can be favorably unified. As a consequence, the design and implementation process are made easier, since the designer has no longer to assign a fixed type to each entity during model construction. The implementation handles entities through an unified data structure and algorithm, and is therefore lightweight and more maintainable. Such an unification is performed without efficiency loss in a concrete simulation methodology called Ioda. According to common sense, we propose to call such an unified entity simply "agent"!