Undoubtedly real-time traffic information strongly influences individual and group driver behaviour. To a lay person, the perceived possible effect of additional (accurate) information is likely to appear unambiguously beneficial. However, just as Braess and Down-Thomson, paradoxes for the addition of road infrastructure, more is not always better. It seems likely that similar negative effects can also occur with the addition of information to route planning. In this paper we show three related results. First, it is indeed the case that highly accurate real-time traffic information can have negative effects on drivers individually and altogether. Secondly, we show that these negative effects specifically arise due to the creation of oscillations in traffic pattern which exacerbate small occurrences of otherwise benign traffic congestion. Lastly, we show that novel adoptions of Random Early Detection strategies dampen such oscillations making real-time information a benefit to outcomes rather than a potential threat.

This paper proposes an algorithm that enables the support for a service market place in which service providers can negotiate and form coalitions in a self-centred approach. We present the main features of the algorithm and evaluate the proposed solution under different technical aspects including social network topology, scalability and convergence to optimal results.

The development of ICT has created a gap between computing processes and the huge volume of available information. Institutions need tools for knowledge management in collaborative environments and these tools should guarantee certain level of quality of service. By other hand, Web services are to become in the industry standard for interoperability but they are far away of providing the required robustness level. This paper proposes to adapt the MAS principles of electronic contracting at supervising knowledge management processes for knowledge sharing using web services, and to apply the descriptive capacity of OWL, as a formal semantic language in order to improve the autonomy of underneath computing processes. A SupervIsed CoLlabOrative System model (SICLOS) was defined –supervised from a global perspective, based on the semantic management of actions and resources. Dynamic processes control is improved and thereby, the knowledge management service. In this paper, the achieved results are discussed.

The remarkable recent story of Kyle MacDonald who, by means of a sequence of bartering exchanges between July 2005 and July 2006, managed to trade a small red paperclip for a full sized house in the town of Kipling Saskatchewan has inspired interesting debates about the nature of such feats and questions as to how they might come about. While bartering is arguably the world's oldest form of trade, there are still cases such as this which surprise us. Although there are many factors to consider in Kyle's achievement, his feat raises basic questions about the nature of the trades made and to what extent they are repeatable. In this paper we provide an intuitive model for the type of trading environment experienced Kyle and study its consequences in order to analyze in particular whether such trading phenomena require altruistic agents to be present in the environment and extending the experience with multiple goal seeking agents.

This paper presents a middleware to help designers in the implementation of contract-aware agent-based services. The middleware provides several components, including a contract manager, a communication manager and a workflow manager, which combine to allow agents to manage contracts and the actions associated with them. The middleware is built as part of a Web service implementation of the IST-CONTRACT framework. An electronic commerce example is used to illustrate how the components of the middleware facilitates the management and Execution of agreements in a contract at run-time.

File sharing networks are among the most popular applications of Peer-to-Peer (P2P) technology to date [1] and have been widely studied in terms of performance, behavior, topology and other properties. A persistent theme throughout this research has been the evidence that many P2P file sharing systems rely on the presence of altruistic users, who provide files, network capacity or some other goods without obvious personal gain and are potentially damaged by the presence of too many free-riders (users who consume resources but do not provide to others in return). In this paper we will explore the use of simple market mechanisms for P2P file sharing which function without the need of altruistic users and consider the conditions under which such markets may be viable.

The allocation of resources amongst a set of autonomous entities with contradicting interests is a recurring and relevant theme in distributed domains. In this paper we present the design, implementation and evaluation of a distributed directory service based on a bartering mechanism in order to improve robustness in data retention. A directory service maps the names of network resources to their respective network addresses. A distributed directory service maintains this information not at a single node in a network, but across many nodes. The major challenge addressed in this paper is to build a workable system which not only responds to queries from users but A) ensures that directory items are never lost in the system and B) optimizes query response time with respect to different patterns of query arrival.

This paper presents ongoing work in the definition of a contracting language, which can be used not only to specify agreed behaviour in service-oriented architectures but also for agentmediated systems. The contract clauses are based in deontic notions such as obligations, permissions and prohibitions. The language not only covers the contract document itself but several layers of communication, including the messages and the protocols for contract handling. An example of usage is presented.

Despite several examples of deployed agent systems, there remain barriers to the large-scale adoption of agent technologies. In order to understand these barriers, this paper considers aspects of marketing theory which deal with diffusion of innovations and their relevance to the agents domain and the current state of diffusion of agent technologies. In particular, the paper examines the role of standards in the adoption of new technologies, describes the agent standards landscape, and compares the development and diffusion of agent technologies with that of object-oriented programming. The paper also reports on a simulation model developed in order to consider different trajectories for the adoption of agent technologies, with trajectories based on various assumptions regarding industry structure and the existence of competing technology standards. We present details of the simulation model and its assumptions, along with the results of the simulation exercises.

The concept of provenance is already well understood in the study of fine art where it refers to the trusted, documented history of some work of art. Given that documented history, the object attains an authority that allows scholars to understand and appreciate its importance and context relative to other works of art. This same concept of provenance may also be applied to data and information generated within a computer system; particularly when the information is subject to regulatory control over an extended period of time. Today's distributed architectures (not only Agent technologies, but also Web Services' and GRID architectures) suffer from limitations, such as lack of mechanisms to trace results. Provenance enables users to trace how a particular result has been arrived at by identifying the individual and aggregated services that produced a particular output. In this chapter we present the main results of the EU PROVENANCE project and how these can be valuable in agent-mediated healthcare applications. For the latter we describe the Organ Transplant Management Application (OTMA), one of the demonstrator applications developed.

The analysis of societies demonstrates the recurrent nature of small world topology in the interactions of elements in such worlds. The small world topology proves to have beneficial properties for system's performance in many cases, however there are also scenarios where the small world topology's properties negatively affect the system's outcome; thus in depth knowledge on the small world weaknesses is needed in order to develop new generations of artificial societies and new models of economic systems. In this paper, a multi-agent system based on request for proposal protocol and coalition formation organisational paradigm is used to analyse properties of small world social networks of agents. Experiments center on nodes in the network with high betweenness and in particular the distribution of agents in the population across these nodes. Results show that small world topology scenarios lose their beneficial properties when non-competitive agents are positioned as high betweeness nodes in the network.

This paper explores a general model of economic exchange between heterogeneous agents representing firms, traders, or other socioeconomic entities, that self-organise into coalitions to fulfil specific tasks. In particular, the work addresses coalition formation problems in which many tasks are addressed to the same population over time in an iterative fashion. The purpose of the paper is to describe the necessary elements that lead the system to an equilibrium state and asses the impact of coalition size constraints on the type of collaboration patterns established between agents. By using a novel data mining technique called collaboration graphs it is possible to see that stable states can be reached using simple iterative protocols and that the number of stable states increases as the coalition size limit decreases.

This paper focuses on the Coalition Formation paradigm as a market mechanism. Concretely, Coalition Formation occurs as part of a wider open world and may occur many times during the lifetime of a population of agents. This fact can in some circumstances be exploited by agents to re-use existing partial coalition and social relationships over time to improve Coalition Formation efficiency. The aim of the work is to analyze the dynamics of two concrete rational behaviors (Competitive and Conservative strategies) and, in particular, to investigate how agents in a heterogeneous population cluster together across multiple Coalition Formation episodes and varying tasks. Preliminary resuls are also shown regarding the manner in which playing distinct strategies interact with one another.

In small scale multi-agent environments, every agent is aware of all of the others. This allows agents to evaluate the potential outcomes of their interaction for each of their possible interaction partners. However, this farsighted knowledge becomes an issue in large scale systems, leading to a combinatorial explosion in evaluation and is unrealistic in communication terms. Limited awareness of other agents is therefore the only plausible scenario in many large-scale environments. This limited awareness can be modeled as a sparse social network in which agents only interact with a limited subset of agents known to them. In this paper, we explore a model of dynamic multi-agent coalition formation in which agents are connected via fixed underlying social networks that exhibit different well known structures such as Small World, Randomand Scale Freetopologies. Agents follow different exploratory policies and are distributed in the network according to a variety of metrics. The primary results of the paper are to demonstrate different positive and negative properties of each topology for the coalition formation problem. In particular we show that despite positive properties for many problems, Small Worldtopologies introduce blocking factors which hinder the emergence of good coalition solutions in many configurations.

Web Services-based solutions for interoperating processes are considered to be one of the most promising technologies for achieving truly interoperable functioning in open environments. In the last three years, the specification in particular of agreements between resource / service providers and consumers, as well as protocols for their negotiation have been proposed as a possible solution for managing the resulting computing systems. In this report, the state of the art in the area of contract-based web service applications is closely studied, identifying current limitations and possibilities. On the basis of this analysis, a general model for contract specification, negotiation, agreement, execution and management is introduced. Such a model has broad applicability both in electronic business integration and distributed knowledge management systems for decision support. Initial work presented here was completed in September 2005 and is published here as background for the European Commission funded project IST CONTRACT http://www.ist-contract.org/. Towards a Contract-based Interoperation Model Index

Open source, open formats and open content have a significant role to play in the development of educational programs. Until now the debate has focused on open methods for delivery and licensing of educational material. But open methods are just as important for education itself, and IT in particular, as they are for delivery. We reflect on the experiences of the @LIS-TechNET project and argue that in emerging regions such as Latin America, a focus on open methods in IT education provides a more sustainable long-term benefit to the IT sector and the economy as a whole than proprietary methods.

Resource allocation in distributed systems is an exciting area of research. Inherent properties in this environment, such as strategic users acting selfishly and the structure of the environment within which exchanges occur, are relevant challenges to study. This paper proposes a market–based resource allocation in a distributed environment and explores the effects of network structure on the allocation of performance together. Further, we proposed mechanisms to improve the performance of the market. The proposed model, as well as mechanisms to maximize the allocation of objects/goods have been implemented and studied experimentally. The results obtained show how topology affects the performance of the market. Using information propagation mechanisms clearly contributes to its improvement.