They are able to learn, to reason about their knowledge and to adapt themselves to their environment. Agents represent humans as well as other interactive carriers of information. The behavior of agents is determined by their roles describing rights and obligations. Agents have locations in time and space. Channels connect these locations and facilitate communication.
Protocols regulate the communication between agents.
The formal basis of a medium is a logical system, comprising the language for modeling the multi-agent system, as well as the language in which the agents represent their knowledge. The logical system determines the formal relation between the representation of information objects, and the world, partially represented in the medium. It comprises also the notion of deduction of knowledge from the knowledge bases of agents and the way, a medium with its agents evolves. We consider the memotype of a medium as well as the processes of selection of mems or memotypes, respectively, of agents and the process of adaptation and learning. Particular to this notion of medium is that it is dynamic and active.