Role-based semantics for agent communication

Applied Ontology

There are two main traditions in defining a semantics for agent communication languages, based either on mental attitudes or on social commitments. These traditions, even if they share the idea of speech acts as operators with preconditions and effects, and agents playing roles like speaker and hearer, rely on completely distinct ontologies. Not only does the mental attitudes approach refer to concepts like belief, desire, goal or intention and is the social commitment approach based on the notion of commitment, but the two approaches also refer to distinct speech acts, distinct types of dialogue games, and so on. In this paper, we propose a common ontology for both approaches based on public mental attitudes attributed to roles. Public mental attitudes avoid the problems of mentalistic semantics, such as the unverifiability of private mental states, and they allow the reuse of the logics and implementations developed for FIPA compliant approaches. Moreover, a common ontology of communication primitives allows for the construction of agents participating to dialogues with both FIPA and social commitments compliant agents. The challenge of agent communication languages whose semantics is based on public mental attitudes, such as our rolebased semantics, is to define mappings from existing languages to the new one. In this paper we show how to map the two existing traditions to our role-based ontology of public mental attitudes and we show how it allows for a comparison. Moreover, to test the generality of our new ontology for agent communication languages, we show how to extend the social commitment approach to cope with persuasion dialogue too.

2006 IEEE/WIC/ACM International Conference on Intelligent Agent Technology, 2006

We consider agents having multiple communication sessions at the same time. We assume that FIPA semantics of agent communication languages can still be used when we attribute mental attitudes for each session, which we call the roles of the agents, and we assume that we have to distinguish the mental attitudes attributed to the roles from the mental attitudes of the agents. We consider several consequences of the distinction between the mental attitudes attributed to the roles and the mental attitudes attributed to the agent. First, in attributing mental attitudes to an agent or to one of its roles, we argue that only mental attributes are attributed to an agent's role when these attributes follow directly from the agent's communication. They are therefore public in the sense that every agent who has overheard the session, has the same beliefs about the mental attitudes of the role. Second, the moves permitted to the dialogue participants in the same dialogue game are based on the role only, such that different kind of moves can be specified in different types of dialogue games. Obligations are associated to roles related to institutions which can enforce them by means of sanctions. Third, expectations are based both on the mental attitudes ascribed to the agent and to the role.

2006

One of the most important aspects of the research on agent interaction is the de nition of agent communication languages (ACLs), and the speci cation of a proper formal semantics of such languages is a crucial prerequisite for the usefulness and acceptance of arti cial agency. Nevertheless, those ACLs which are still mostly used, especially the standard FIPA-ACL, have a communication act semantics in terms of the participating agents' mental attitudes (viz.

Proceedings of the Workshop on Agent Languages and …, 2000

Lecture Notes in Computer Science, 2007

In this paper we develop a semantics of our approach based on commitments and arguments for conversational agents. We propose a logical model based on CTL* (Extended Computation Tree Logic) and on dynamic logic. Called Commitment and Argument Network (CAN), our formal framework based on this hybrid approach uses three basic elements: social commitments, actions that agents apply to these commitments and arguments that agents use to support their actions. The advantage of this logical model is to gather all these elements and the existing relations between them within the same framework. The semantics we develop here enables us to reflect the dynamics of agent communication. It also allows us to establish the important link between commitments as a deontic concept and arguments. On the one hand CTL* enables us to express all the temporal aspects related to the handling of commitments and arguments. On the other hand, dynamic logic enables us to capture the actions that agents are committed to achieve.

2002

In recent years, the importance of defining a standard framework for agent communication language (ACL) has been widely recognized. However, classical proposals (mentalistic semantics and social semantics) fail to meet the objectives of verifiability and flexibility required in complex interactions involving heterogenous agents possibly designed by different programmers. In this paper we propose an ACL which allows heterogenous agents to engage flexibly in the different kinds of dialogues identified by Walton and Krabbe in . To this end, we propose a two-layered semantics which includes a commitment level and a reasoning level based on argumentation.

Lecture Notes in Computer Science, 2005

In this paper we present a modal semantics for our approach based on social commitments and arguments for conversational agents. Our formal framework based on this approach uses three basic elements: social commitments, actions that agents apply to these social commitments and arguments that agents use to support their actions. This framework, called Commitment and Argument Network (CAN), formalizes the agents' interactions as a network in which agents manipulate commitments and arguments. More precisely, we propose a logical model (called DCTL* CAN ) based on CTL* and on dynamic logic for this framework. The advantage of this logical model is to bring together social commitments, actions, argumentation relations, and the relations existing between these three elements within the same framework. Our semantics makes it possible to represent the dynamics of agent communication. It also allows us to establish the important link between social commitments as a deontic concept and arguments. The final objective of this paper is to propose a unified framework for pragmatics and semantics of agent communication by defining logic-based protocols.

Our goal is to extend agent communication languages for persuasion dialogues. We distinguish action commitments from propositional commitments, because both limit future moves, but an action commitment is fulfilled when the hearer believes that the action is performed, whereas a propositional commitment is fulfilled only when the hearer concedes to the proposition -where concessions are the absence of a belief to the contrary, and prevent further challenges. Using a common model for both kind of commitments and a role-based semantics of agent communication languages, we show how propositional commitments are related to public beliefs and action commitments to public goals.