541 research outputs found
Optimizing the computation of overriding
We introduce optimization techniques for reasoning in DLN---a recently
introduced family of nonmonotonic description logics whose characterizing
features appear well-suited to model the applicative examples naturally arising
in biomedical domains and semantic web access control policies. Such
optimizations are validated experimentally on large KBs with more than 30K
axioms. Speedups exceed 1 order of magnitude. For the first time, response
times compatible with real-time reasoning are obtained with nonmonotonic KBs of
this size
Knowledge Representation Concepts for Automated SLA Management
Outsourcing of complex IT infrastructure to IT service providers has
increased substantially during the past years. IT service providers must be
able to fulfil their service-quality commitments based upon predefined Service
Level Agreements (SLAs) with the service customer. They need to manage, execute
and maintain thousands of SLAs for different customers and different types of
services, which needs new levels of flexibility and automation not available
with the current technology. The complexity of contractual logic in SLAs
requires new forms of knowledge representation to automatically draw inferences
and execute contractual agreements. A logic-based approach provides several
advantages including automated rule chaining allowing for compact knowledge
representation as well as flexibility to adapt to rapidly changing business
requirements. We suggest adequate logical formalisms for representation and
enforcement of SLA rules and describe a proof-of-concept implementation. The
article describes selected formalisms of the ContractLog KR and their adequacy
for automated SLA management and presents results of experiments to demonstrate
flexibility and scalability of the approach.Comment: Paschke, A. and Bichler, M.: Knowledge Representation Concepts for
Automated SLA Management, Int. Journal of Decision Support Systems (DSS),
submitted 19th March 200
Access Restrictions to and with Description Logic Web Ontologies
Access restrictions are essential in standard information systems and became an issue for ontologies in the following two aspects. Ontologies can represent explicit and implicit knowledge about an access policy. For this aspect we provided a methodology to represent and systematically complete role-based access control policies. Orthogonally, an ontology might be available for limited reading access. Independently of a specific ontology language or reasoner, we provided a lattice-based framework to assign labels to an ontology’s axioms and consequences. We looked at the problems to compute and repair one or multiple consequence labels and to assign a query-based access restriction. An empirical evaluation has shown that the algorithms perform well in practical scenarios with large-scale ontologies
Provenance-aware knowledge representation: A survey of data models and contextualized knowledge graphs
Expressing machine-interpretable statements in the form of subject-predicate-object triples is a well-established practice for capturing semantics of structured data. However, the standard used for representing these triples, RDF, inherently lacks the mechanism to attach provenance data, which would be crucial to make automatically generated and/or processed data authoritative. This paper is a critical review of data models, annotation frameworks, knowledge organization systems, serialization syntaxes, and algebras that enable provenance-aware RDF statements. The various approaches are assessed in terms of standard compliance, formal semantics, tuple type, vocabulary term usage, blank nodes, provenance granularity, and scalability. This can be used to advance existing solutions and help implementers to select the most suitable approach (or a combination of approaches) for their applications. Moreover, the analysis of the mechanisms and their limitations highlighted in this paper can serve as the basis for novel approaches in RDF-powered applications with increasing provenance needs
Model-based Semantic Conflict Analysis for Software- and Data-Integration Scenarios
The semantic conflict analysis, which is the focus of this technical report, is an approach to automate various design-time verification activities which can be applied during software- or data-integration processes. Specifically, the aspects of semantic matching of business processes and the underlying IT infrastructure as well as of technical aspects of the composite heterogeneous systems will be investigated. The report is part of the BIZYCLE project, which examines applicability of model-based methods, technologies and tools to the large-scale industrial software and data integration scenarios. The semantic conflict analysis is thus part of the overall BIZYCLE conflict analysis process, comprising of semantic, structural, communication, behavior and property analysis, aiming at facilitating and improving standard integration practice. Therefore, the project framework will be briefly introduced first, followed by the detailed semantic annotation and conflict analysis descriptions, and further backed up with the semantic conflict analysis motivation/illustration scenario
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