Enrico Oliva

Cognitive stigmergy: towards a framework based on agents and artifacts

Stigmergy has been adopted in MAS (multi-agent systems) and in other fields as a technique for realising forms of emergent coordination in societies composed by a large amount of ant-like, nonrational agents. In this paper we discuss a conceptual (and engineering) framework for exploring the use of stigmergy in the context of societies composed by cognitive / rational agents, as a means for supporting highlevel, knowledge-based social activities.multi-agent We refer to this kind of stigmergy as cognitive stigmergy. Cognitive stigmergy is based on the use of artifacts as tools populating and structuring the agent working environment, and which agents perceive, share and rationally use for their individual goals. Artifacts are environment abstractions that mediate agent interaction and enable emergent coordination: as such, they can be used to encapsulate and enact the stigmergic mechanisms and the shared knowledge upon which emergent coordination processes are based. In this paper, we start exploring this scenario introducing an agent-based framework for cognitive stigmergy based on artifacts. After discussing the main conceptual issues--the notion of cognitive stigmergy and the role of artifacts--, we sketch an abstract architecture for cognitive stigmergy, and outline its implementation upon the TuCSoN agent coordination infrastructure.

Co-argumentation artifact for agent societies

In a social context, people have only partial knowledge about the world and use arguments in order to solve problems, to reduce conflicts, or to exchange information. Argumentation is a dialogic process, and could occur through direct interaction, or through supports of some sorts--like blackboards, or electronic fora. The same holds for intelligent agents in a multi-agent system (MAS); here, however, it is not clear what could act as a support for argumentation between agents, external to the agents themselves. To this end, this work exploits the agents and artifacts (A&A) meta-model for MAS, exploring the use of artifacts for agent argumentation within a MAS. Along this line, the first aim of this work is to design an argumentation component based on Dungs preferred semantics, combining it with artifact abstraction in order to realise a social support for argumentation in MAS. Using argumentation within the A&A meta-model, we introduce here the notion of Co-Argumentation Artifact (CAA) as an artifact specialised in managing arguments and providing a coordination service for argumentation process in a MAS. In order to give concreteness to our proposal, we also discuss a first CAA deployment based on logic programming and tuple centres exploiting the TuCSoN infrastructure.

Argumentation and Artifact for Dialogue Support

Intelligent and autonomous software agents may engage in dialogue and argument with one another, and much recent research has considered protocols, architectures and frameworks for this. Just as with human dialogues, such agent dialogues may be facilitated by the presence of a mediator, able to summarise different positions, identify common assumptions and inconsistencies, and make appropriate interventions in the dialogue. Drawing on the theory of co-ordination artifacts in multi-agent systems, we propose a formal framework to explicitly represent the functions of a mediator artifact. We then describe an implementation of this framework using the TuCS oN coordination infrastructure for MAS, where the mediator artifact is realised by a tuple centre--a programmable tuple space.

A Framework for Engineering Interactions in Java-based Component Systems

This paper describes a Java-based framework for the development of component-based software systems supporting the specification of the logic of component interactions as a first-class aspect. Java is used as the reference development language. On the one side, the framework makes it possible to specify the logic of interaction at the component-level, in terms of input and output interfaces, the events generated and observed by a component, and related information about the management of the control flow. On the other side, it is possible to specify the logic of interaction at the inter-component level, providing a modelling and linguistic support for designing and (dynamically) programming the glue among the components, enabling general forms of observation, control and construction of the interaction space. As a result, the framework supports the coordination of components at different levels: from interoperability among heterogeneous and unknown components, to the support for dynamic introduction, removal and update of components, to general coordination patterns, such as workflow. The framework adopts first-order logic as the reference computational model for describing and defining the logic of interaction: the modalities adopted by components to interact, the coordination laws gluing the components and the interaction events occurring in the system are expressed as facts and rules. They compose the (evolving) logic theories describing and defining the interaction at the system level, and can be observed and controlled at runtime to allow dynamic re-configurability.