Wamberto Weber Vasconcelos

On the insufficiency of ontologies: problems in knowledge sharing and alternative solutions

One of the benefits of formally represented knowledge lies in its potential to be shared. Ontologies have been proposed as the ultimate solution to problems in knowledge sharing. However even when an agreed correspondence between ontologies is reached that is not the end of the problems in knowledge sharing. In this paper we explore a number of realistic knowledge-sharing situations and their related problems for which ontologies fall short in providing a solution. For each situation we propose and analyse alternative solutions.

Applying Prolog programming techniques

Abstract Much of the skill of Prolog programming comes from the ability to harness its comparatively simple syntax in sophisticated ways. It is possible to provide an account of part of the activity of Prolog programming in terms of the application of techniques—standard patterns of program development which may be applied to a variety of different programming problems. Numerous researchers have attempted to provide formal definitions of Prolog techniques but there has been little standardization of the approach and the computational use of techniques has been limited to small portions of the programming task. We demonstrate that techniques knowledge can be used to support programming in a wide variety of areas: editing, analysis, tracing, transformation and techniques acquisition. We summarize the main features of systems implemented by the authors for each of these types of activity and set these in the context of previous work, using a standard style of presentation. We claim that a techniques-based system which integrates these features would be worth more than the sum of its parts, since the same techniques knowledge can be shared by the different subsystems.

Skeleton-based agent development for electronic institutions

In this paper we describe an approach for semi-automatic agent development. We focus on the scenario in which agents are designed to follow an electronic institution, a formalism to specify open agent organisations. In our approach, an initial design pattern is automatically extracted from a given electronic institution. This pattern is then offered to programmers willing to develop agents to perform in the electronic institution. Our approach supports developers when modifying the initial simple design pattern into more sophisticated programs.

An Opportunistic Approach for Logic Program Analysis and Optimisation Using Enhanced Schema-Based Transformations

We propose an opportunistic approach for performing program analysis and optimisation: opportunities for improving a logic program are systematically attempted, either by examining its procedures in an isolated fashion, or by checking for conjunctions within clauses that can be used as joint specifications. Opportunities are represented as enhanced schema-based transformations, generic descriptions of inefficient programming constructs and of how these should be altered in order to confer a better computational behaviour on the program. The programming constructs are described in an abstract manner using an enhanced schema language which allows important features to be highlighted and irrelevant details to be disregarded.

A Lifecycle for Models of Large Multi-agent Systems

Two key issues in building multi-agent systems concern their scalability and engineering open systems. We offer solutions to these potential problems by introducing a lifecycle for models of large multi-agent systems. Our proposal connects a model for the collective analysis of agent systems with an individual-based model. This approach leads on to a virtuous cycle in which individual behaviours can be mapped on to global models and vice-versa. We illustrate our approach with a formal example but relatively easy for engineers to follow and adapt.

A lightweight capability communication mechanism

A persistent problem in managing the interaction between distributed agents is to be able to coordinate the communication between systems without having continually to ask each system for information about what it can do. One form of coordination is through the use of capability descriptions that are advertised by each agent and managed by a brokering mechanism. The task of the broker (which may be centralised or distributed among the agents) is to accept queries and to hypothesise the means of obtaining answers based only on the capability descriptions. This has the advantage that plans for coordinating answers can be constructed by the broker without having to contact the agents. Brokering, however, is not straightforward because capability descriptions can be complex and may be conditional on interactions with other agents. Brokering must also take into account the possibility that the ontologies used by each agent may differ, so some means of relating the terminology of capabilities of agents is needed. Many sophisticated systems exist for tackling parts of this problem but there have been comparatively few attempts to build lightweight engineering solutions by adapting well established methods. We describe a simple way of implementing a lightweight but powerful brokering mechanism.

An approach to rapid prototyping of large multi-agent systems

Engineering individual components of a multi-agent system and their interactions is a complex and error-prone task in urgent need of methods and tools. Prototyping is a valuable technique to help software engineers explore the design space while gaining insight and a feel for the dynamics of the system; prototyping also allows engineers to learn more about the relationships among design features and the desired computational behaviour. In this paper we describe an approach to building prototypes of large multi-agent systems with which we can experiment and analyse results. We have implemented an environment embodying our approach. This environment is supported by a distributed platform that helps us achieve controlled simulations.

A logic-based approach for automatic synthesis and maintenance of web sites

In this paper we introduce and justify the use of high-level specifications for synthesising and managing Web sites. Ours is a declarative approach employing computational logic for representing information and knowledge and also for generating the actual site in a format suitable for browsing. Additionally, our specifications contain definitions of logic-based agents that are constructed as part of the synthesis of the Web site specification and can be employed to automate the maintenance of parts of the site.

Why Ontologies Are Not Enough for Knowledge Sharing

Knowledge sharing is difficult. One reason is that it is hard to decide how to describe a domain in a way which suits everyone interested in the knowledge. Tackling this problem has been a central theme of the surge in ontological research over recent years. Unfortunately, getting an agreed ontology is not the end of our problems, since the way we represent knowledge is intimately linked to the inferences we expect to perform with it. We introduce three inference systems and discuss the problems of having knowledge passing through them, which are representative of complex problems we may need to solve for knowledge sharing.

Slicing knowledge-based systems: techniques and applications

Slicing is a process for automatically obtaining subparts of a program responsible for specific computations. It has been employed within conventional procedural programming to solve a number of software development issues. We have adapted and extended slicing techniques originally proposed for procedural languages, to knowledge-based systems. Our techniques comprise a representation proposal for the successful and failed inferences performed by the system, a means to detect and represent the dependences among parts of the system, a formal definition of relevance among these parts and an algorithm proven correct to obtain executable slices of a system. We illustrate the usefulness of the slicing process with practical applications.