We propose a method for the definition of interaction protocols to be used in open multiagent systems. Starting from the assumption that language is the fundamental component of every interaction, we first propose a semantics for Agent Communication Languages based on the notion of social commitment, and then use it to define the meaning of a set of basic communicative acts. Second, we propose a verifiable and application-independent method for the definition of interaction protocols, whose main component is the specification of an interaction diagram specifying which actions may be performed by agents under given conditions. Interaction protocols fully rely on the application-independent meaning of communicative acts. We also propose a set of soundness conditions that can be used to verify whether a protocol is reasonable. Finally, our approach is exemplified by the definition of an interaction protocol for English auctions.

In this paper we propose an operational method for the definition of the semantics of Agent Communication Languages based on the notion of social commitment. Our proposal is suitable for open interaction frameworks where agents, designed by independent constructors, dynamically enter and leave different interaction systems. In this type of environments it is crucial to define a standard and commonly accepted semantics for the exchanged messages. We give an operational specification of commitment and introduce temporal propositions for the representation of the contents of commitments within an object-oriented paradigm. Then we use operations on commitments to define the meaning of a set of communicative acts that is complete with respect to Searle's taxonomy of illocutionary acts, and give an example of the use of communicative acts in an interaction protocol.

Abstract. In this paper we propose an application-independent model for the definition of artificial institutions that can be used to define open multi-agent systems. Such a model of institutional reality makes us able also to define an objective and external semantics of a commitment-based Agent Communication Language (ACL). In particular we propose to regard an ACL as a set of conventions to act on a fragment of institutional reality, defined in the context of an artificial institution. Another contribution of the work presented in this paper is an operational definition of norms, a crucial component of artificial institutions. In fact in open systems interacting agents might not conform to the specifications. We regard norms as event-driven rules that when are fired by events happening in the system create or cancel a set of commitments. An interesting aspect of our proposal is that both the definition of the ACL and the definition of norms are based on the same notion of commitment. Therefore an agent capable of reasoning on commitments can reason on the semantics of communicative acts and on the system of norms.

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In this paper we propose an operational method to express the meaning of the messages exchanged among agents that interact in open environments. In an open environment, like for example the Internet, agents are usually designed by different constructors, so it is very important to define the meaning of a standard, widely accepted Agent Communication Language. We express the meaning of messages using the social notion of commitment. Commitments are defined operationally within an object-oriented paradigm. We give an operational specification of the commitment class that includes the concepts of conditional commitment and precommitment. Then we use commitment objects to define the meaning of some interesting speech acts, and give an example of their use in negotiation.