Towards a Formal Theory of Communication for Multi-agent Systems

Agents in multiagent systems interact to a large extent by communicating. Such communication may be fruitfully studied from the point of view of speech act theory. In order for multiagent systems to be formally and rigorously designed and analyzed, a semantics of speech acts that gives their objective model-theoretic conditions of satisfaction is needed. However, most research into multiagent systems that deals with communication provides only informal descriptions of the different message types used. And this problem is not addressed at all by traditional speech act theory or by AI research into discourse understanding. I provide a formal semantics for the major kinds of speech acts at a level that has not been considered before. The resulting theory applies uniformly to a wide range of multiagent systems. Some applications of this theory are outlined, and some of its theorems listed. 1 Introduction Multiagent systems are ubiquitous in Artificial Intelligence. Even in the simplest such systems, the epithet is justified only if the agents involved interact with each other in different ways. One of the most natural ways in which intelligent interaction may occur is through communication, especially communication about action. Agents may command, request, advise, or permit each other to do certain actions. They may also promise actions of their own, or prohibit those of others. When complex multiagent systems are to be designed or analyzed a formal theory of the kinds of communication that may take place among agents would be crucial. Unfortunately , no theory is currently available that provides the objective semantics of the messages exchanged. This paper describes research that has been done to fill this void. This research uses ideas about the ability and intentions of situated agents that were motivated and developed on independent grounds, albeit with a view to their final application to this problem [Singh, 1991; Singh, 1990a; Singh, 1990b]. This connection to other theories is reason to be reassured that this theory is not ad hoc, and will coherently fit in a bigger picture. The theory presented in this paper has ramifications in several subareas of AI, notably, multiagent planning and action , autonomous agents, and cooperative work [Gasser and Huhns, 1989; Huhns, 1987]. Traditionally, speech act theory classifies communications or messages into several kinds of illocutionary acts [Searle, 1969; Searle and Vanderveken, 1985]. These include assertivcs, directives, commisives, permissives and prohibitives. Briefly, assertives are statements of fact; directives are commands, …