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The Semantic Web

Finding and Using Information from the Web Intelligently


AITopics > Representation | Systems & Languages > Semantic Web

  

Definition of the Area

(From the now-dormant Electronic Transactions On Artificial Intelligence)

"The area is concerned with Modeling Semantics of Web Information: Theory, Methods, and Applications.

Currently, the web is an incredible large, mainly static information source. The heavy burden in information access, extraction and interpretation is left to the human user. Tim Berners-Lee coined the vision of a "semantic web" in which background knowledge is stored on the meaning or content of web resources through the use of machine-processable metadata. The semantic web should be able to support automated services based on these descriptions of semantics. The semantic or "knowledge" web is seen as a key factor in finding a way out of the growing problems of traversing the expanding web space, where currently most web resources can only be found through syntactic matches (e.g., keyword search).

This ETAI area is targeted at all research efforts aimed at constructing, maintaining and using such a knowledge-intensive information and service web. Not surprisingly, our field is interdisciplinary in its very nature covering various aspects dealt with in various communities of Artificial Intelligence and Computer Science. It covers aspects from knowledge engineering, databases and information systems, knowledge representation, information retrieval, digital libraries, multi-agent systems, natural-language processing, and machine learning.

[The research area encompasses] the following categories:

  • Metadata, knowledge markup, and formal annotations of web information;
  • Information extraction, automatic and semi-automatic generation of meta data for web information.
  • Knowledge representation for the web.
  • Generic and heuristic reasoning methods for the web.
  • Integration of databases in the knowledge web.
  • Interoperability of web services at the semantic and pragmatic levels.
  • Standard ontologies for content description of web information.
  • Distributed ontologies, knowledge composition and transformation,
  • Scalability of knowledge-intensive web services,
  • Content-based information retrieval.
  • Knowledge retrieval.
  • Tool environments, development methodologies, case studies and applications for and of the knowledge web,
  • Web-based knowledge management and electronic commerce."


Good Starting Places

AI Knows It’s Out There. Red Herring (August 22, 2005 print issue). "The idea behind the semantic web is to catalog information in web documents according to the higher meaning of the words -- their ontology -- rather than the mere presence of text. 'I believe the semantic web is the Next Big Thing,' says Jim Hendler, a computer science professor at the University of Maryland. To explain the concept of the semantic web, he cites the example of a Google search for the median age at which people start smoking in Baltimore. 'I'm interested in the concept of age, not specific digits,' he says."

The Semantic Web. By Tim Berners-Less, James Hendler, and Ora Lassila. Scientific American (May 2001). "In philosophy, an ontology is a theory about the nature of existence, of what types of things exist; ontology as a discipline studies such theories. Artificial-intelligence and Web researchers have co-opted the term for their own jargon, and for them an ontology is a document or file that formally defines the relations among terms. The most typical kind of ontology for the Web has a taxonomy and a set of inference rules." Be sure to read the entire article for a clear explanation of these (and many other) concepts and terms.

The Semantic Web. From Semaview Inc. Several short articles presenting one company's overview of the Semantic Web.

General Readings

  • The Semantic Web In Action - Corporate applications are well under way, and consumer uses are emerging. By Lee Feigenbaum, Ivan Herman, Tonya Hongsermeier, Eric Neumann and Susie Stephens. Scientific American (December 2007; subscription req'd). "Six years ago in this magazine, Tim Berners-Lee, James Hendler and Ora Lassila unveiled a nascent vision of the Semantic Web: a highly interconnected network of data that could be easily accessed and understood by any desktop or handheld machine. ... The enabling technologies have come of age. A vibrant community of early adopters has agreed on standards that have steadily made the Semantic Web practical to use. Large companies have major projects under way that will greatly improve the efficiencies of in-house operations and of scientific research. Other firms are using the Semantic Web to enhance business-to-business interactions and to build the hidden data-processing structures, or back ends, behind new consumer services. And like an iceberg, the tip of this large body of work is emerging in direct consumer applications, too."

A Smarter Web - New technologies will make online search more intelligent--and may even lead to a "Web 3.0." By John Borland. Technology Review (March / April 2007 issue). "The Semantic Web community's grandest visions, of data-surfing computer servants that automatically reason their way through problems, have yet to be fulfilled. But the basic technologies that [Eric] Miller shepherded through research labs and standards committees are joining the everyday Web. They can be found everywhere--on entertainment and travel sites, in business and scientific databases--and are forming the core of what some promoters call a nascent 'Web 3.0.' ... Since 1998, researchers at W3C, led by [Tim] Berners-Lee, had been discussing the idea of a 'semantic' Web, which not only would provide a way to classify individual bits of online data such as pictures, text, or database entries but would define relationships between classification categories as well. Dictionaries and thesauruses called 'ontologies' would translate between different ways of describing the same types of data, such as 'post code' and 'zip code.' All this would help computers start to interpret Web content more efficiently. In this vision, the Web would take on aspects of a database, or a web of databases. ... In articles and talks, Berners-Lee and others began describing a future in which software agents would similarly skip across this 'web of data,' understand Web pages' metadata content, and complete tasks that take humans hours today. ... At the beginning of 2001, the effort to realize this vision became official. The W3C tapped Miller to head up a new Semantic Web initiative, unveiled at a conference early that year in Hong Kong."

AI Magazine cover

Special Issue of AI Magazine, Volume 24, Number 3 (Fall 2003): Ontology Research (Guest Editorial) by Christopher Welty; Special Issue Articles: Sweetening WORDNET with DOLCE  by Aldo Gangemi, Nicola Guarino, Claudio Masolo, and Alessandro Oltramari; Where Are the Semantics in the Semantic Web?  by Michael Uschold; WEBODE in a Nutshell  by Julio César Arpírez, Oscar Corcho, Mariano Fernández-López, and Asunción Gómez-Pérez; Ontologies for Corporate Web Applications  by Leo Obrst, Howard Liu, and Robert Wray; The Process Specification Language (PSL) Theory and Applications  by Michael Grüninger and Christopher Menzel; The CIDOC Conceptual Reference Module: An Ontological Approach to Semantic Interoperability of Metadata  by Martin Doerr.

Tiny Circuits: Tim Berners-Lee discusses the future of the Web. NPR Talk of the Nation: Science Friday With Ira Flatow. [Radio Interview; November 1, 2002]

Where are the Semantics in the Semantic Web? Michael Uschold, AI Magazine, Vol 24, No 3 (Fall, 2003). "To use web content, machines need to know what to do when they encounter it, which, in turn, requires the machine to know what the content means (that is, its semantics). The challenge of developing the semantic web is how to put this knowledge into the machine. The manner in which it is done is at the heart of the confusion about the semantic web. The goal of this article is to clear up some of this confusion."

Building The Web of Tomorrow - Creators Say 'Semantic' Web Will Be Smarter. By Sophia Kingman. ABCNEWS.com (December 21, 2001). "Semantic means 'of or relating to meaning,' and this new Web will have content better identified so that, for example, future search engines will be able to understand context and discard the irrelevant. ... 'Ontologies are nothing but names with standard meanings. And in a world of data exchange names are incredibly important, because you and I cannot exchange information about a thing unless we agree on the name for the thing,' [R.V.] Guha said."

Course Syllabus

Semantic Web Technologies course 2009/2010. Taught by Jos de Bruijn and Maria Keet. KRDB Research Centre, Faculty of Computer Science, University of Bozen-Bolzano. %quot;Aim: The aim of the course is to make the students familiar with the Semantic Web, with technologies used on the Semantic Web, and with applications using Semantic Web technologies. The course will focus on the theoretical background of various languages on the Semantic Web such as RDF, SPARQL, and OWL, and the practical use of these languages on the Semantic Web. In addition, the course will focus on ontology engineering and important application areas for Semantic Web technology, namely the Life Sciences."

Related Resources

Semantic Web Agents Project, Maryland Information and Network Dynamics Lab, University of Maryland, College Park. "Many of the pages contain links which will let you either let you see the Semantic Web markup directly (the machine-readable markup) or take you to pages describing how the pages are created and the tools used to power them. Please enjoy exploring this site and learning about many of the ways Semantic Web technology can be used to provide new capabilities on the Web." - excerpt from Why do we call this the first site on the Semantic Web?

Cycorp, Inc. Here's just a sample of what you'll find there:

  • The Semantic Web. "The success of the Semantic Web hinges on solving two key problems: (1) enabling novice users to create semantic markup easily, and (2) developing tools that can harvest the semantically rich but ontologically inconsistent web that will result. ... Once end-users are empowered by the Semantic Web to create their own ontologies, there will be an urgent need to interrelate those ontologies in a useful way. The key to harvesting this new semantic information will be the creation of the Semantic Web-aware agents that can cope with a diversity of meanings and inconsistencies across local ontologies. These agents will need the capability to interpret, understand, elaborate, and translate among the many heterogeneous local ontologies that will populate the the Semantic Web. ... Cycorp's effort is targeted at the situation where the ontologies to be translated are not richly specified, where a novice has quickly created a 'light weight' ontology, just to get started."
    • "OpenCyc is the open source version of the Cyc technology, the world's largest and most complete general knowledge base and commonsense reasoning engine. Cycorp set up an independent organization, OpenCyc.org, to disseminate and administer OpenCyc.... Release 1.0 of OpenCyc will include: 6,000 concepts: an upper ontology for all of human consensus reality; 60,000 assertions about the 6,000 concepts, interrelating them, constraining them, in effect (partially) defining them...."
    • The Syntax of CycL. "CycL is a formal language whose syntax derives from first-order predicate calculus (the language of formal logic) and from Lisp. In order to express common sense knowledge, however, it goes far beyond first order logic."
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