We extend the description logic EL++ with reflexive roles
and range restrictions, and show that subsumption remains tractable if
a certain syntactic restriction is adopted. We also show that subsumption
becomes PSpace-hard (resp. undecidable) if this restriction is weakened
(resp. dropped). Additionally, we prove that tractability is lost when
symmetric roles are added: in this case, subsumption becomes ExpTime-
hard
What is the Semantic Web? Read on for a brief introduction to the Semantic Web, how to get started using it, and to understand why we should invest in making our content semantic.
Ontotext GraphDB is a highly-efficient and robust graph database with RDF and SPARQL support. This documentation is a comprehensive guide, which explains every feature of GraphDB as well as topics such as setting up a repository, loading and working with data, tuning its performance, scaling, etc.
he W3C Web Ontology Language (OWL) is a Semantic Web language designed to represent rich and complex knowledge about things, groups of things, and relations between things.
The OWL 2 Web Ontology Language, informally OWL 2, is an ontology language for the Semantic Web with formally defined meaning. OWL 2 ontologies provide classes, properties, individuals, and data values and are stored as Semantic Web documents. OWL 2 ontologies can be used along with information written in RDF, and OWL 2 ontologies themselves are primarily exchanged as RDF documents.
OWL lets you say much more about your data model, it shows you how to work efficiently with database queries and automatic reasoners, and it provides useful annotations for bringing your data models into the real world.
The Visual Notation for OWL ontologies (VOWL - pronounced "vowel" [vou-uh l]) provides graphical representations for elements of the Web Ontology Language (OWL). It allows for an integrated view on ontologies that visualizes classes (circles) along with their individuals (sections in the circles) and property relations (connecting lines and arrows).
PoolParty Thesaurus Manager
Meets high expectations on usability
Provides customisable metadata schemas
Strictly built on open W3C standards
PoolParty Extractor
Highly performant text mining algorithms
Adresses different data sources
Delivers relevant context information
PoolParty Search
High end refinement assistants
Search different sources with one API
Ready for third party integration
The SKOS API is a Java interface and implementation for the W3C Simple Knowledge Organisation System SKOS. For more information about SKOS see here. An implementation of the SKOS API is provided which uses the OWL 2 API, at present you will need to obtain the OWL API seperately from the OWL 2 website. [UPDATE 12-09-2011] The current release of the SKOS API has been deprecated, a new version_3 developer branch is available in the SVN repository that works with the latest OWL API v3.
For more information please contact the user group at skos-dev@googlegroups.com
The SKOS API is open source and is available under the LGPL License
The SKOS API includes the following components:
An API for the major SKOS constructs and an efficient in-memory reference implementation based on the OWL 2 API
Abstract data model for working for SKOS that avoids commitment to any of the concrete syntaxes, such as RDF
RDF/XML parser and writer
OWL/XML parser and writer
OWL Functional Syntax parser and writer
Turtle parser and writer
Support for extending the underlying SKOS data model via the OWL 2 API
Support for integration with reasoners such as Pellet and FaCT++
Range of convenience methods for working with SKOS
I. Niles, и A. Pease. Proceedings of the International Conference on Formal Ontology in Information Systems - Volume 2001, стр. 2--9. New York, NY, USA, ACM, (2001)
K. Lüttich, T. Mossakowski, и B. Krieg-Brückner. Recent Trends in Algebraic Development Techniques, 17th International Workshop (WADT 2004), том 3423 из Lecture Notes in Computer Science, стр. 106-125. Springer; Berlin; http://www.springer.de, (2005)
O. Kutz, J. Hastings, и T. Mossakowski. 15th International Conference on Artificial Intelligence: Methodology, Systems, Applications, том 7557 из Lecture Notes in Computer Science, стр. 103-111. Springer, (2012)