Protocols represent the allowed interactions among communicating agents. Protocols are essential in applications such as electronic commerce where it is necessary to constrain the behaviors of autonomous agents. Traditional approaches, which model protocols in terms of action sequences, limit the flexibility of the agents in executing the protocols. By contrast, we develop an approach for specifying protocols in which we capture the content of the actions through agents' commitments to one another. We forrealize commitments in a variant of the event calculus. We provide operations and reasoning rules to capture the evolution of commitments through the agents' actions. Using these rules in addition to the basic event calculus axioms enables agents to reason about their actions explicitly to flexibly accommodate the exceptions and opportunities that arise at run time. This reasoning is implemented using an event calculus planner that helps us determine flexible execution paths that respect the protocol specifications.

Negotiation is essential in settings where autonomous agents have conflicting interests and a desire to cooperate. For this reason, mechanisms in which agents exchange potential agreements according to various rules of interaction have become very popular in recent years as evident, for example, in the auction and mechanism design community. However, a growing body of research is now emerging which points out limitations in such mechanisms and advocates the idea that agents can increase the likelihood and quality of an agreement by exchanging arguments which influence each others ’ states. This community further argues that argument exchange is sometimes essential when various assumptions about agent rationality cannot be satisfied. To this end, in this article, we identify the main research motivations and ambitions behind work in the field. We then provide a conceptual framework through which we outline the core elements and features required by agents engaged in argumentation-based negotiation, as well as the environment that hosts these agents. For each of these elements, we survey and evaluate existing proposed techniques in the literature and highlight the major challenges that need to be addressed if argument-based negotiation research is to reach its full potential.

The Kanger-Lindahl theory of normative positions attempts to use a combination of deontic logic (the logic of obligation and permission) and a logic of action/agency to give a formal account of obligations, duties, rights, and other complex normative concepts. This paper presents a generalisation and further development of this theory, together with methods for its automation and application to practical examples. The resulting theory is intended to be applied in the representation and analysis of laws, regulations, and contracts, in the specification of aspects of computer systems, in multi-agent systems, and as a contribution to the formal theory of organisations. Particular attention is paid to representations at varying levels of detail and the relationships that hold between them. The last part presents Norman-G, an automated support system intended to facilitate application of the theory to the analysis of practical problems, with a small example to illustrate its use.

This survey introduces existing approaches to agent communications languages (ACLs) and particularly, conversation policies (CPs) which can be viewed as general constraints on the sequence of semantically coherent messages leading to a goal. Then limitations of these CPs are discussed in detail, particularly limitations on flexibility and specification. Finally, ACLs are viewed from the dialectic point of view, and some approaches are introduced in this context: some focusing on commitment-based protocols and others on dialogue-game based protocols.

Abstract. Commitments among agents are widely recognized as an important basis for organizing interactions in multiagent systems. We develop an approach for formally representing and reasoning about commitments in the event calculus. We apply and evaluate this approach in the context of protocols, which represent the interactions allowed among communicating agents. Protocols are essential in applications such as electronic commerce where it is necessary to constrain the behaviors of autonomous agents. Traditional approaches, which model protocols merely in terms of action sequences, limit the flexibility of the agents in executing the protocols. By contrast, by formally representing commitments, we can specify the content of the protocols through the agents ’ commitments to one another. In representing commitments in the event calculus, we formalize commitment operations and domain-independent reasoning rules as axioms to capture the evolution of commitments. We also provide a means to specify protocol-specific axioms through the agents ’ actions. These axioms enable agents to reason about their actions explicitly to flexibly accommodate the exceptions and opportunities that may arise at run time. This reasoning is implemented using an event calculus planner that helps determine flexible execution paths that respect the given protocol specifications.

Abstract. 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. 1

This paper provides a formal framework for developing the idea of normative co-ordination. This idea is based on the assumption that agents can achieve flexible co-ordination by conferring normative positions to other agents. These positions include duties, permissions, and powers. In particular, we introduce the idea of declarative power, i.e. the capacity of the power-holder of creating normative positions by simply "proclaiming" such positions. We account also for the concepts of representation -- the representative's capacity of acting in the name of his principal --, and mandate -- the mandatee's duty to act as the mandator has requested.

Abstract. In this paper we provide a formal framework for developing the idea of normative co-ordination. We argue that this idea is based on the assumption that agents can achieve flexible co-ordination by conferring normative positions to other agents. These positions include duties, permissions, and powers. In particular, we introduce the idea of declarative power, which consists in the capacity of the power-holder of creating normative positions, involving other agents, simply by “proclaiming” such positions. In addition, we account also for the concepts of representation, consisting in the representative’s capacity of acting in the name of his principal, and of mandate, which corresponds the mandatee’s duty to act as the mandator has requested. 1

Electronic markets, dispute resolution and negotiation protocols are three types of application domains that can be viewed as open agent societies. Key characteristics of such societies are agent heterogeneity, conflicting individual goals and unpredictable behaviour. Members of such societies may fail to, or even choose not to, conform to the norms governing their interactions. It has been argued that systems of this type should have a formal, declarative, verifiable, and meaningful semantics. We present a theoretical and computational framework being developed for the executable specification of open agent societies. We adopt an external perspective and view societies as instances of normative systems. In this paper we demonstrate how the framework can be applied to specifying and executing a contract-net protocol. The specification is formalised in two action languages, the C+ language and the Event Calculus, and executed using respective software implementations, the Causal Calculator and the Society Visualiser. We evaluate our executable specification in the light of the presented case study, discussing the strengths and weaknesses of the employed action languages for the specification of open agent societies.

In this paper we propose to regard an Agent Communication Language (ACL) as a set of conventions to act on a fragment of institutional reality, defined in the context of an artificial institution. Within