Technical Reports on Agents

Logic-Based Specification Environments for Multi-Agent Systems

Real-world applications are usually characterized by heterogeneous distributed entities that interact following complex coordination protocols and that dynamically and autonomously modify their strategies during this interaction; these systems are extremely difficult to model and implement, and traditional software engineering tools and techniques are often insufficient to cope with this complexity. For this reason a new software engineering paradigm, the Agent-Oriented Software Engineering (AOSE) has joined, over the past ten years, more traditional approaches. AOSE analyzes and designs systems based on the key abstraction of the agent, an autonomous entity situated in some environment, able to perceive the environment itself and to react to changes occurring in it, able to take the initiative when appropriate and capable of communication with other agents in the system. Different approaches have been studied to engineer multi-agent systems (MAS), comprising structured but non-mathematical methodologies as well as logic-based ones. ARPEGGIO, an ongoing software engineering international project involving logic programming groups from USA, Australia and Italy, is designing a logic-based prototyping environment for engineering this kind of complex applications using mainly (but not only) logic-based languages. The focus of this thesis is thus on multi-agent system development environments which use logic-based approaches to specification and implementation. Our contribution is three-fold:
1. We have described many informal and formal approaches to AOSE, with particular attention to the last ones. We have analyzed different kinds of logics and, for each of them, we have provided the description and an example of use of one agent specification languages based on it.
2. We have analyzed some existing MAS Development Kits (MASDKs) to understand which engineering approach, if any, is more commonly adopted and which could be the desiderata for a more powerful environment as ARPEGGIO aims to become. We have compared and drawn a taxonomy of five MASDKs and we have provided rules of thumb to chose the right MASDK to do the right thing.
3. Finally, we have designed the extension of two logic-based MASDKs, IMPACT and CaseLP, with new capabilities. IMPACT has been extended to deal with errors (IMPACT error-tolerant agents), and CaseLP has been extended to become a multi-language distributed environment which could integrate, in the future, the IMPACT specification language, thus taking a first concrete step towards ARPEGGIO's development.

The compressed postscript version of this report is available through anonymous ftp at ftp.disi.unige.it, in /pub/person/MascardiV/Tesi/mythesis.ps.gz (1180320 Bytes).
The uncompressed pdf version of this report is available through anonymous ftp at ftp.disi.unige.it, in /pub/person/MascardiV/Tesi/mythesis.pdf (1712836 Bytes).

@phdthesis{MascardiPhdThesis02,
author = {V. Mascardi},
title = {Logic-Based Specification Environments for Multi-Agent Systems},
year = {2002},
school = {Computer Science Department of Genova University},
address = {Genova, Italy},
note = {DISI-TH-2002-04. Downloadable from \url{ftp://ftp.disi.unige.it/person/MascardiV/Tesi/mythesis.ps.gz}}}

CaseLP, a Rapid Prototyping Environment for Agent-Based Software

Intelligent agents and multi-agent systems are increasingly recognized as an innovative way of analyzing, designing and implementing complex, heterogeneous and distributed software applications. The agent-based view offers a powerful and high level conceptualization that software engineers can exploit to considerably improve the way in which software is realized. Agent-based software engineering is a recent and very interesting research area. Due to its novelty, in this field there is still no evidence of well-established practices for the development of agent-based applications and thus experimentation in this direction is a very important issue.
This dissertation presents CaseLP (Complex Applications Specification Environment based on Logic Programming), an experimental environment based on logic programming for rapid prototyping of agent-based software applications. CaseLP provides developers with a prototyping method and a set of tools and languages which allow the realization of an executable prototype of a software application as a society of interacting agents.
A prototype is built along three dimensions: task organization, knowledge organization and interaction organization. Task organization concerns the specification of tasks performed by the prototype, the distribution of tasks among agents, the services that agents provide and request to accomplish their tasks and how they behave in order to execute their services. CaseLP provides tools for task organization: an architectural description language is adopted to describe the prototype in terms of agents classes, instances, their provided and required services, and their communication links. Knowledge organization concerns the description of knowledge that agents manipulate and use to properly behave. Ontologies are used in CaseLP to explicitly structure the knowledge on the prototype's application domain, as well as to unambiguously describe characteristics and properties of agents. A rule-based language is used to define procedural knowledge of reactive and/or proactive agents. Interaction organization concerns the way agents interact with each other. A tool for conversation description is used in CaseLP to define the sequences of messages that are exchanged to provide any service, and the hierarchical relationships among sequences. Prototypes are implemented in an extended Prolog-like language. Visualization and simulation tools are included in CaseLP to visualize and trace a prototype execution and to collect statistics on it.
The dissertation also investigates the use of high level specification languages to describe sophisticated agent architectures and multi-agent systems. A linear logic language is used to specify a BDI architecture. An imperative language for the specification of heterogeneous agent architectures is presented and discussed.
The research on CaseLP has been undertaken with two main objectives. Our first goal was showing that logic programming facilitates the realization of an environment for the (semi) formal development of agent-based prototypes. The second goal was to demonstrate that such an environment can be effectively used for the rapid prototyping of complex real-world software applications. We argue that CaseLP is a good example of how the first goal can be satisfied; the prototyping, in CaseLP, of some real-world case-studies is the demonstration of the applicability of our environment. In particular, the dissertation presents in details KICKER, a prototype for a decision support system to be used by European traffic operators in the management of freight trains movements between inter-modal centres and yards. KICKER is a project in co-operation between the Information Systems Division of Italian Railways (FS S.p.A.) and the Computer Science Department at the University of Genova, Italy.

The compressed postscript version of this report is available through anonymous ftp at ftp.disi.unige.it, in /pub/person/MascardiV/Tesi/ZiniThesis.ps.gz.

@phdthesis{ZiniPhdThesis01,
author = {F. Zini},
title = {CaseLP, a Rapid Prototyping Environment for Agent-Based Software},
year = {2001},
school = {Computer Science Department of Genova University},
address = {Genova, Italy},
note = {DISI-TH-2001-03. Downloadable from \url{ftp://ftp.disi.unige.it/person/MascardiV/Tesi/ZiniThesis.ps.gz}}}