Semantic Web - Wikipedia, the free encyclopedia
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Semantic Web
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The Semantic Web is a project that intends to create a universal medium for information exchange by giving meaning (semantics), in a manner understandable by machines, to
the content of documents on the Web. Currently under the direction of the Web's creator, Tim Berners-Lee of the World Wide Web Consortium, the Semantic Web extends the
ability of the World Wide Web through the use of standards, markup languages and related processing tools.
Contents
1 Relationship to the World Wide Web
2 Components of the Semantic Web
3 See also
4 References
5 External links
Relationship to the World Wide Web
Currently, the World Wide Web is based primarily on documents written in HTML, a language that is useful for describing, with an emphasis on visual presentation, a body of
structured text interspersed with multimedia objects such as images and interactive forms. HTML has limited ability to classify the blocks of text on a page, apart from the roles
they play in a typical document's organization and in the desired visual layout.
For example, with HTML and a tool to render it (perhaps Web browser software, perhaps another user agent), one can create and present a page that lists items for sale. The
HTML of this catalog page can make simple, document-level assertions such as "this document's title is 'Widget Superstore'". But there is no capability within the HTML itself
to unambiguously assert that, say, item number X586172 is an Acme Gizmo with a retail price of €199, or that it is a consumer product. Rather, HTML can only say that the
span of text "X586172" is something that should be positioned near "Acme Gizmo" and "€199", etc. There is no way to say "this is a catalog" or even to establish that "Acme
Gizmo" is a kind of title or that "€199" is a price. There is also no way to express that these pieces of information are bound together in describing a discrete item, distinct from
other items perhaps listed on the page.
The Semantic Web addresses this shortcoming, using the descriptive technologies RDF and OWL, and the data-centric, customizable markup language XML. These
technologies are combined in order to provide descriptions that supplement or replace the content of Web documents. Thus, content may manifest as descriptive data stored in
Web-accessible databases, or as markup within documents (particularly, in XHTML interspersed with XML, or, more often, purely in XML, with layout/rendering cues stored
separately). The machine-readable descriptions allow content managers to add meaning to the content, thereby facilitating automated information gathering and research by
computers.
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Semantic Web - Wikipedia, the free encyclopedia
http://en.wikipedia.org/wiki/Semantic_web
Components of the Semantic Web
The Semantic Web is comprised of the standards and tools of XML, XML Schema, RDF, RDF Schema and OWL. The OWL Web Ontology Language Overview
(http://www.w3.org/TR/owl-features/) describes the function and relationship of each of these components of the Semantic Web:
XML provides a surface syntax for structured documents, but imposes no semantic constraints on the meaning of these documents.
XML Schema is a language for restricting the structure of XML documents.
RDF is a datamodel for objects ("resources") and relations between them. It provides a simple semantics for this datamodel. These datamodels can be represented in an
XML syntax.
RDF Schema is a vocabulary for describing properties and classes of RDF resources, with a semantics for generalization-hierarchies of such properties and classes.
OWL adds more vocabulary for describing properties and classes: among others, relations between classes (e.g. disjointness), cardinality (e.g. "exactly one"), equality,
richer typing of properties, characteristics of properties (e.g. symmetry), and enumerated classes.
The intent is to enhance the usability and usefulness of the Web and its interconnected resources through:
documents "marked up" with semantic information (an extension of the HTML <meta> tags used in today's Web pages to supply information for Web search engines
using web crawlers). This could be machine-readable information about the human-readable content of the document (such as the creator, title, description, etc., of the
document) or it could be purely metadata representing a set of facts (such as resources and services elsewhere in the site). (Note that anything that can be identified with
a Uniform Resource Identifier (URI) can be described, so the semantic web can reason about people, places, ideas, cats etc.)
common metadata vocabularies (ontologies) and maps between vocabularies that allow document creators to know how to mark up their documents so that agents can use
the information in the supplied metadata (so that Author in the sense of 'the Author of the page' won't be confused with Author in the sense of a book that is the subject
of a book review).
automated agents to perform tasks for users of the Semantic Web using this metadata
web-based services (often with agents of their own) to supply information specifically to agents (for example, a Trust service that an agent could ask if some online store
has a history of poor service or spamming).
The primary facilitators of this technology are URIs (which identify resources) along with XML and namespaces. These, together with a bit of logic, form RDF, which can be
used to say anything about anything. As well as RDF, many other technologies such as Topic Maps and pre-web artificial intelligence technologies are likely to contribute to the
Semantic Web.
A popular application of the Semantic Web is Friend of a Friend (or FoaF), which describes relationships among people and other agents in terms of RDF.
An implementation of a Semantic Web Browser is the BigBlogZoo (http://www.bigblogzoo.com) . Nearly 80,000 xml feeds have been categorised using the DMOZ schema and
can be spidered.
See also
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DAML+OIL
OWL
Description logic
DOAC
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Semantic Web - Wikipedia, the free encyclopedia
http://en.wikipedia.org/wiki/Semantic_web
Dublin Core
Knowledge representation, Knowledge technologies
Semantic spectrum
Web syndication
microformats
References
Michael C. Daconta, Leo J. Obrst, Kevin T. Smith: The Semantic Web: A Guide to the Future of XML, Web Services, and Knowledge Management, John Wiley & Sons,
ISBN 0-471-43257-1
Dieter Fensel, Wolfgang Wahlster, Henry Lieberman, James Hendler: Spinning the Semantic Web: Bringing the World Wide Web to Its Full Potential, MIT Press, ISBN
0-262-06232-1
Steffen Staab, Rudi Studer: Handbook on Ontologies, Springer Verlag, Heidelberg. 2004, ISBN 3-540-40834-7
Vladimir Geroimenko, Chaomei Chen: Visualizing the Semantic Web, Springer Verlag, ISBN 1-85233-576-9
John Davies, Dieter Fensel, Frank van Harmelen: Towards the Semantic Web: Ontology-Driven Knowledge Management, John Wiley & Sons, ISBN 0-470-84867-7
Grigoris Antoniou, Frank van Harmelen: A Semantic Web Primer, The MIT Press, ISBN 0-262-01210-3
Jeffrey T. Pollock, Ralph Hodgson_2: Adaptive Information: Improving Business through Semantic Interoperability, Grid Computing, and Enterprise Integration, John
Wiley, ISBN 0-471-48854-2
External links
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Tim Berners-Lee: Weaving the Semantic Web (http://www.digitaldivide.net/articles/view.php?ArticleID=20) , by Andy Carvin. Published by the Digital Divide Network,
October 2004
World Wide Web Technology Architecture: A conceptual analysis (http://newdevices.com/publicaciones/www) , by Luciano Polo.
Libby Miller and Simon Price: The Semantic Web is Your Friend (http://www.freepint.com/issues/270504.htm#feature) , FreePint 27th May 2004 No.160
Semantic Web Overview (http://www.w3.org/2001/sw/Activity)
OWL Web Ontology Language Overview (http://www.w3.org/TR/owl-features/)
ZDNet Article (http://zdnet.com.com/2100-1104_2-5156243.html?tag=zdfd.newsfeed)
W3C Semantic Web initiative (http://www.w3.org/2001/sw/)
Tim Berners-Lee's 1998 roadmap paper (http://www.w3.org/DesignIssues/Semantic.html)
Scientific American article on The Semantic Web (http://www.sciam.com/article.cfm?articleID=00048144-10D2-1C70-84A9809EC588EF21&catID=2) , May 2001
Semantic Web Community Portal (http://www.semanticweb.org/)
The Semantic Web In One Day (http://km.aifb.uni-karlsruhe.de/projects/swsc)
The Rule Markup Initiative (http://www.dfki.uni-kl.de/ruleml/)
International Semantic Web Conference (ISWC) (http://iswc.semanticweb.org/)
European Semantic Web Conference (ESWC) 2006 (http://www.eswc2006.org/)
Semantic Web Research (http://www.aifb.uni-karlsruhe.de/WBS/)
Friend-of-a-Friend-o-matic (http://www.ldodds.com/foaf/foaf-a-matic.html)
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Semantic Web - Wikipedia, the free encyclopedia
http://en.wikipedia.org/wiki/Semantic_web
Not Your Father’s Internet (http://www.microsoft.com/issues/essays/01-17internet.asp) by Bill Gates
Usecase: a semantic travel guide (http://alliknow.net)
Semantic Web Encyclopedia of Terms (http://seokeywordanalysis.com/seotools/infobase/semanticweb/)
Retrieved from "http://en.wikipedia.org/wiki/Semantic_Web"
Categories: Knowledge representation | Semantic web
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