Empirical-Rational Semantics of Agent Communication

The missing of an appropriate semantics of agent communication languages is one of the most challenging issues of contemporary AI. Although several approaches to this problem exist, none of them is really suitable for dealing with agent autonomy, which is a decisive property of artificial agents. This paper introduces an observation-based approach to the semantics of agent communication, which combines benefits of the two most influential traditional approaches to agent communication semantics, namely the mentalistic (agent-centric) and the objectivist (i.e., commitment- or protocol-oriented) approach. Our approach makes use of the fact that the most general meaning of agent utterances lays in their expectable consequences in terms of agent actions, and that communications result from hidden but nevertheless rational and to some extent reliable agent intentions. In this work, we present a formal framework which enables the empirical derivation of communication meanings from the observation of rational agent utterances, and introduce thereby a probabilistic and utility-oriented perspective of social commitments

Generalized commitment alignment

The interoperability of interacting components means that their expectations of each other remain in agreement. A commitment captures what one agent (its creditor) may expect from another agent (its debtor). Chopra and Singh (C&S) motivate commitment alignment as a meaning-based form of interoperation and show how to ensure alignment among agents despite asynchrony. Although C&S’s approach demonstrates the key strengths of relying on commitment semantics, it suffers from key shortcomings, which limit its applicability in practice. One, C&S do not model commitments properly, causing unacceptable interference between commitments in different transactions. Two, they require that the communication infrastructure guarantee first-in first-out (FIFO) delivery of messages for every agent-agent channel. Three, C&S guarantee alignment only in quiescent states (where no messages are in transit); however, such states may never obtain in enactments of real systems. Our approach retains and enhances C&S’s key strengths and avoids their shortcomings by providing a declarative semantics-based generalized treatment of alignment. Specifically, we (1) motivate a declarative notion of alignment relevant system states termed completeness; (2) prove that it coincides with alignment; and (3) provide the computations by which a system of agents provably progresses toward alignment assuming eventual delivery of messages

Interaction and communication among autonomous agents in multiagent systems

The main goal of this doctoral thesis is to investigate a fundamental topic of research within the Multiagent Systems paradigm: the problem of defining open, heterogeneous, and dynamic interaction frameworks. That is to realize interaction systems where multiple agents can enter and leave dynamically and where no assumptions are made on the internal structure of the interacting agents. Such topic of research has received much attention in the past few years. In particular the need to realize applications where artificial agents can interact negotiate, exchange information, resources, and services has become more and more important thanks to the advent of Internet. I started my studies by developing a trading agent that took part to an international trading on-line game: the First Trading Agent Competition (TAC). During the design and development phase of the trading agent some crucial and critical troubles emerged: the problem of accurately understanding the rules that govern the different auctions; and the problem of understanding the meaning of the numerous messages. Another general problem is that the internal structure of the developed trading agent have been strongly determined by the peculiar interface of the interaction system, consequently without any changes in its code, it would not be able to take part to any other competition on the Web. Furthermore the trading agent would not have been able to exploit opportunities, to handle unexpected situations, or to reason about the rules of the various auctions, since it is not able to understand the meaning o the exchanged messages. The presence of all those problems bears out the need to find a standard common accepted way to define open interaction systems. The most important component of every interaction framework, as is remarked also by philosophical studies on human communication is the institution of language. Therefore I start to investigate the problem of defining a standard and common accepted semantics for Agent Communication Languages (ACL). The solutions proposed so far are at best partial, and are considered as unsatisfactory by a large number of specialists. In particular, they are unable to support verifiable compliance to standards and to make agents responsible for their communicative actions. Furthermore such proposals make the strong assumption that every interacting agent may be modeled as a Belief-Desire-Intention agent. What is required is an approach focused on externally observable events as opposed to the unobservable internal states of agents. Following Speech Act Theory that views language use as a form of action, I propose an operational specification for the definition of a standard ACL based on the notion of social commitment. In such a proposal the meaning of basic communicative acts is defined as the effect that it has on the social relationship between the sender and the receiver described through operation on an unambiguous, objective, and public "object": the commitment. The adoption of the notion of commitment is crucial to stabilize the interaction among agents, to create an expectation on other agents behavior, to enable agents to reason about their and other agents actions. The proposed ACL is verifiable, that is, it is possible to determine if an agent is behaving in accordance to its communicative actions; the semantics is objective, independent of the agent's internal structure, flexible and extensible, simple, yet enough expressive. A complete operational specification of an interaction framework using the proposed commitment-based ACL is presented. In particular some sample applications of how to use the proposed framework to formalize interaction protocols are reported. A list of soundness conditions to test if a protocol is sound is proposed

Extend Commitment Protocols with Temporal Regulations: Why and How

The proposal of Elisa Marengo's thesis is to extend commitment protocols to explicitly account for temporal regulations. This extension will satisfy two needs: (1) it will allow representing, in a flexible and modular way, temporal regulations with a normative force, posed on the interaction, so as to represent conventions, laws and suchlike; (2) it will allow committing to complex conditions, which describe not only what will be achieved but to some extent also how. These two aspects will be deeply investigated in the proposal of a unified framework, which is part of the ongoing work and will be included in the thesis.Comment: Proceedings of the Doctoral Consortium and Poster Session of the 5th International Symposium on Rules (RuleML 2011@IJCAI), pages 1-8 (arXiv:1107.1686

Inner Speech and Metacognition: a defense of the commitment-based approach

A widespread view in philosophy claims that inner speech is closely tied to human metacognitive capacities. This so-called format view of inner speech considers that talking to oneself allows humans to gain access to their own mental states by forming metarepresentation states through the rehearsal of inner utterances (section 2). The aim of this paper is to present two problems to this view (section 3) and offer an alternative view to the connection between inner speech and metacognition (section 4). According to this alternative, inner speech (meta)cognitive functions derivate from the set of commitments we mobilize in our communicative exchanges. After presenting this commitment-based approach, I address two possible objections (section 5)