A Logical Model of Social Commitment for Agent Communication

As part of the goal of developing a genuinely open multiagent system, many efforts are devoted to the definition of a standard Agent Communication Language (ACL). The aim of this paper is to propose a logical framework for the definition of ACL semantics based upon the concept of (social) commitment. Our framework relies on the assumption that agent communication should be analyzed in terms of communicative acts, by means of which agents create and manipulate commitments, provided certain contextual conditions hold. We propose formal definitions of such actions in the context of a temporal logic that extends CTL* with past-directed temporal operators. In the system we propose, called CTL±, time is assumed to be discrete, with no start or end point, and branching in the future. CTL± is then extended to represent actions and commitments; in particular, we formally define the conditions under which a commitment is fulfilled or violated. Finally, we show how our logic of commitment can be used to define the semantics of an ACL.