1,721,481 research outputs found
An agent system for query routing search
No full textThis thesis examines the issues affecting the design and implementation of scalable agent-based systems which use query routing for resource or service discovery. Query routing is a type of informed distributed search in which agents reason about the capabilities of other agents in order to constrain the scope of a query and the cost of processing it. The technique of query routing bears many similarities to the use of mediators in multi-agent systems. We discuss the relation between mediator-based systems for service discovery in multi-agent systems and the use of query routing in distributed information systems, and present a novel model of the query routing task which we have used to examine the complexity and scalability of a number of commonly encountered architectures for resource or service discovery. This theory-based approach is complemented by our practical experiences of building query routing systems using our simple agent framework, Phyle. Finally, we perform an empirical study of the behaviour of different query routing systems in order to validate our model, using our simulator for query routing systems, Paraphyle.</p
Scalability Issues for Query Routing Service Discovery
No full textIn this paper, we discuss the relationship between mediator-based systems for service discovery in multi-agent systems, and the technique of query routing used for resource discovery in distributed information systems. We then construct a model of the query routing task which we use to examine the complexity and scalability characteristics of a number of commonly encountered architectures for resource or service discovery
Resource Description Framework (RDF)
No full textThe Resource Description Framework (RDF) is the standard knowledge representation language for the Semantic Web, an evolution of the World Wide Web that aims to provide a well-founded infrastructure for publishing, sharing and querying structured data. This article provides an introduction to RDF and its related vocabulary definition language RDF Schema, and explains its relationship with the OWL Web Ontology Language. Finally, it provides an overview of the historical development of RDF and related languages for Web metadata
Using provenance to efficiently propagate SPARQL updates on RDF source graphs
No full textTo promote sharing on the Semantic Web, information is published in machine-readable structured graphs expressed in RDF or OWL. This allows information consumers to create graphs using other source graphs. Information, however, is dynamic and when a source graph changes, graphs based on it need to be updated as well to preserve their integrity. To avoid regenerating a graph after one of its source graphs changes, since that approach can be expensive, we rely on its provenance to reduce the resources needed to reflect changes to its source graph. Accordingly, we expand the W3C PROV standard and present RGPROV, a vocabulary for RDF graph creation and update. RGPROV allows us to understand the dependencies a graph has on its source graphs and facilitates the propagation of the SPARQL updates applied to those source graphs through it. Additionally, we present a model that implements a modified DRed algorithm which makes use of RGPROV to enable partial modifications to be made on the RDF graph, thus reflecting the SPARQL updates on the source graph efficiently, without having to keep track of the provenance of each triple. Hence, only SPARQL updates are communicated, the need for complete re-derivation is done away with, and provenance is kept at the graph level making it better scalable
Distributed stream reasoning
No full textStream Reasoning is the combination of reasoning techniques with data streams. In this paper, we present our approach to enable rule-based reasoning on semantic data streams in a distributed manne
Decentralised Approaches for Self-Adaptation in Agent Organisations
No full textSelf-organising multi-agent systems provide a suitable paradigm for developing autonomic computing systems that manage themselves. Towards this goal, we demonstrate a robust, decentralised approach for structural adaptation in explicitly modelled problem solving agent organisations. Based on self-organisation principles, our method enables the autonomous agents to modify their structural relations to achieve a better allocation of tasks in a simulated task-solving environment. Specifically, the agents reason about when and how to adapt using only their history of interactions as guidance. We empirically show that, in a wide range of closed, open, static and dynamic scenarios, the performance of organisations using our method is close (70-90%) to that of an idealised centralised allocation method and is considerably better (10-60%) than the current state of the art decentralised approaches
Uncommon patterns - Authoring with story specific structures
No full text. In interactive narrative research there has been a lot of interest in common structural patterns, both as a way of critically analysing work and as a scaffolding mechanism for authoring systems. But stories can contain uncommon patterns that are unique to that story. These may be just as challenging to manage, but are much harder to support in an authoring tool precisely because they are bespoke. In this paper we look at uncommon patterns in interactive story designs, and report on some initial work to support these using a Domain Specific Language (DSL) based on typescript. We show how this approach does allow for the easy construction of repeating complex structure, but also that the technical and expertise barrier for the use of such systems is high. We then consider how the main benefits of this approach may be made more widely accessible. Our work shows that support for Uncommon Patterns would be a useful addition to authoring systems (in both the writing, and editing/revision stages), but also that more work is necessary if they are to be become more widely accessibl
Digital natives? Investigating young people’s critical skills in evaluating web based information
No full textHyperstructure Maintenance Costs in Large-scale Wikis
No full textWiki systems have developed over the past years as lightweight, community-editable, web-based hypertext systems. With the emergence of Semantic Wikis, these collections of interlinked documents have also gained a dual role as ad-hoc RDF graphs. However, their roots lie at the limited hypertext capabilities of the World Wide Web: embedded links, without support for composite objects or transclusion. In this paper, we present experimental evidence that hyperstructure changes, as opposed to content changes, form a substantial proportion of editing effort on a large-scale wiki. The experiment is set in the wider context of a study of how the technologies developed during decades of hypertext research may be applied to improve management of wiki document structure and, with semantic wikis, knowledge structure
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