Norm Emergence in Multi-Agent Societies

Norms are shared expectations of behaviours that exist in human societies. Norms help societies by increasing the predictability of individual behaviours and by improving cooperation and collaboration among members. Norms have been of interest to multi-agent system researchers, as software agents intend to follow certain norms. But, owing to their autonomy, agents sometimes violate norms, which needs monitoring. In order to build robust MAS that are norm compliant and systems that evolve and adapt norms dynamically, the study of norms is crucial. Our objective in this chapter is to propose a mechanism for norm emergence in artificial agent societies and provide experimental results. We also study the role of autonomy and visibility threshold of an agent in the context of norm emergence.

Application of Uncertain Variables to Knowledge-Based Resource Distribution

The chapter concerns a class of systems composed of operations performed with the use of resources allocated to them. In such operation systems, each operation is characterized by its execution time depending on the amount of a resource allocated to the operation. The decision problem consists in distributing a limited amount of a resource among operations in an optimal way, that is, in finding an optimal resource allocation. Classical mathematical models of operation systems are widely used in computer supported projects or production management, allowing optimal decision making in deterministic, well-investigated environments. In the knowledge-based approach considered in this chapter, the execution time of each operation is described in a nondeterministic way, by an inequality containing an unknown parameter, and all the unknown parameters are assumed to be values of uncertain variables characterized by experts. Mathematical models comprising such two-level uncertainty are useful in designing knowledge-based decision support systems for uncertain environments. The purpose of this chapter is to present a review of problems and algorithms developed in recent years, and to show new results, possible extensions and challenges, thus providing a description of a state-of-the-art in the field of resource distribution based on the uncertain variables.

A Formal Analysis of Virtual Enterprise Creation and Operation

This chapter introduces a formal model of virtual enterprises, as well as an analysis of their creation and operation. It is argued that virtual enterprises offer a promising approach to promote both innovations and collaboration between companies. A framework of integrated ICT-tools, called Plug and Play Business, which support innovators in turning their ideas into businesses by dynamically forming virtual enterprises, is also formally specified. Furthermore, issues regarding the implementation of this framework are discussed and some useful technologies are identified.

Using Logic Programming and XML Technologies for Data Extraction from Web Pages

The Web is designed as a major information provider for the human consumer. However, information published on the Web is difficult to understand and reuse by a machine. In this chapter, we show how well established intelligent techniques based on logic programming and inductive learning combined with more recent XML technologies might help to improve the efficiency of the task of data extraction from Web pages. Our work can be seen as a necessary step of the more general problem of Web data management and integration.

How Can We Trust Agents in Multi-Agent Environments? Techniques and Challenges

The field of Multi-agent systems (MAS) has been an active area for many years due to the importance that agents have to many disciplines of research in computer science. MAS are open and dynamic systems where a number of autonomous software components, called agents, communicate and cooperate in order to achieve their goals. In such systems, trust plays an important role. There must be a way for an agent to make sure that it can trust another entity, which is a potential partner. Without trust, agents cannot cooperate effectively and without cooperation they cannot fulfill their goals. Many times, trust is based on reputation. It is an indication that we may trust someone. This important research area is investigated in this book chapter. We discuss main issues concerning reputation and trust in MAS. We present research efforts and give formalizations useful for understanding the two concepts.

Aspects of Openness in Multi-Agent Systems

In the distributed multi-agent systems discussed in this chapter, heterogeneous autonomous agents interoperate in order to achieve their goals. In such environments, agents can be embedded in diverse contexts and interact with agents of various types and behaviours. Mechanisms are needed for coordinating these multi-agent interactions, and so far they have included tools for the support of conversation protocols and tools for the establishment and management of agent groups and electronic institutions. In this chapter, we explore the necessity of dealing with openness in multi-agent systems and its relation with the agent’s autonomy. We stress the importance to build coordination mechanisms capable of managing complex agent societies composed by autonomous agents and introduce our institutional environment approach, which includes the use of commitments and normative spaces. It is based on a metaphor in which agents may join an open system at any time, but they must obey regulations in order to maintain a suitable reputation, that reflects its degree of cooperation with other agents in the group, and make them a more desired partner for others. Coloured Petri Nets are used to formalize a workflow in the institutional environment defining a normative space that guides the agents during interactions in the conversation space.

Survey on the Application of Economic and Market Theory for Grid Computing

In this chapter, we present a survey on some of the commercial players in the Grid industry, existing research done in the area of market-based Grid technology and some of the concepts of dynamic pricing model that we have investigated. In recent years, it has been observed that commercial companies are slowly shifting from owning their own IT assets in the form of computers, software and so forth, to purchasing services from utility providers. Technological advances, especially in the area of Grid computing, have been the main catalyst for this trend. The utility model may not be the most effective model and the price still needs to be determined at the point of usage. In general, market-based approaches are more efficient in resource allocations, as it depends on price adjustment to accommodate fluctuations in the supply and demand. Therefore, determining the price is vital to the overall success of the market.

Example-Based Framework for Propagation of Tasks in Distributed Environments

In this chapter, we propose a generic framework in C# to distribute and compute tasks defined by users. Unlike the more popular models such as middleware technologies, our multinode framework is task-oriented desktop grid. In contrast with earlier proposals, our work provides simple architecture to define, distribute and compute applications. The results confirm and quantify the usefulness of such adhoc grids. Although significant additional experiments are needed to fully characterize the framework, the simplicity of how they work in tandem with the user is the most important advantage of our current proposal. The last section points out conclusions and future trends in distributed environments.

Modeling, Analysing, and Control of Agents Behaviour

An alternative approach to modeling and analysis of agents’ behaviour is presented in this chapter. The agents and agent systems are understood here to be discrete-event systems (DES). The approach is based on the place/transition Petri nets (P/T PN) that yield both the suitable graphical or mathematical description of DES and the applicable means for testing the DES properties as well as for the synthesis of the agents’ behaviour. The reachability graph (RG) of the P/T PN-based model of the agent system and the space of feasible states are found. The RG adjacency matrix helps to form an auxiliary hypermodel in the space of the feasible states. State trajectories representing the actual interaction processes among agents are computed by means of the mutual intersection of both the straight-lined reachability tree (developed from a given initial state toward a prescribed terminal one) and the backtracking reachability tree (developed from the desired terminal state toward the initial one; however, oriented toward the terminal state). Control interferences are obtained on the base of the most suitable trajectory chosen from the set of feasible ones.

Logical Inference Based on Incomplete and/or Fuzzy Ontologies

In this chapter, a concept of using incomplete or fuzzy ontologies in decision making is presented. A definition of ontology and of ontological models is given, as well as their formal representation by taxonomic trees, bi-partite graphs, multigraphs, relations, super-relations and hyper-relations. The definitions of the corresponding mathematical notions are also given. Then, the concept of ontologies representing incomplete or uncertain domain knowledge is presented. This concept is illustrated by an example of decision making in medicine. The aim of this chapter is to give an outlook on the possibility of ontological models extension in order to use them as an effective and universal form of domain knowledge representation in computer systems supporting decision making in various application areas.