1. A processing unit for implementing a multi-agent system having: a) means for implementing a first level, which represents a system; b) means for implementing a second level, which has an abstract representation, reduced to concepts, of the system from the first level; c) means for implementing a third level, which has means for implementing the agents in a multi-agent system; d) an interface for communication between the first and the second level; and having e) an interface for communication between the second and the third level.