XML.com: Uncle Sam's Semantic Web

XML.com: Uncle Sam's Semantic Web: "From the EPA to the Navy, the United States government is coming to see the Semantic Web as a solution to huge data-processing problems. XML.com columnist Paul Ford gets the scoop at the 2004 Semantic Technologies for e-Government Conference.

What did the Semantic Web have to do with the war in Iraq? Not enough, says Jim Hendler, who heads the Mindswap Semantic Web research laboratory at the University of Maryland, speaking at the 2004 Semantic Technologies for e-Government Conference in McLean, Virg., held Sept. 8-9, 2004. 'The beginning of the Iraqi operation was postponed for weeks because information systems couldn't be made interoperable in the time required,' said Hendler. 'Systems couldn't talk to one another.' It was a problem, he says, that a Semantic Web framework could have solved.

Operation Infinite Triples

Hendler's assessment -- that the Semantic Web is the essential glue that will allow large systems to speak to one another, across organizational boundaries -- was shared by many in attendance. A number of agencies and corporations described Semantic Web projects in progress, for client organizations like the Navy, NIST, the Tennessee Valley Authority, the Office of Child Support Enforcement, the Office of Homeland Security, and others."

XML.com: Ontology Tools Survey, Revisited

XML.com: Ontology Tools Survey, Revisited: "Ontologies are a way of specifying the structure of domain knowledge in a formal logic designed for machine processing. The effect on information technology (IT) is to shift the burden of capturing the meaning of data content from the procedural operations of algorithms and rules to the representation of the data itself.

Opening the International Semantic Web Conference in 2003, the conference chair Jim Hendler declared that 'a little semantics goes a long way.' The belief being that infusing even a little semantic quality into our data (residing in web pages, database tables, electronic documents, or whatever) can mean that data is more immediately, broadly, and profoundly usable by all applications aware of the knowledge-representation scheme -- the ontology.

For such reasons, there is a growing sense among researchers and practitioners that ontologies will play an important role in forthcoming information-management solutions. Several conditions predicate this current state of affairs."

RDF Semantics

RDF Semantics: "RDF is an assertional language intended to be used to express propositions using precise formal vocabularies, particularly those specified using RDFS [RDF-VOCABULARY], for access and use over the World Wide Web, and is intended to provide a basic foundation for more advanced assertional languages with a similar purpose. The overall design goals emphasise generality and precision in expressing propositions about any topic, rather than conformity to any particular processing model: see the RDF Concepts document [RDF-CONCEPTS] for more discussion.

Exactly what is considered to be the 'meaning' of an assertion in RDF or RDFS in some broad sense may depend on many factors, including social conventions, comments in natural language or links to other content-bearing documents. Much of this meaning will be inaccessible to machine processing and is mentioned here only to emphasize that the formal semantics described in this document is not intended to provide a full analysis of 'meaning' in this broad sense; that would be a large research topic. The semantics given here restricts itself to a formal notion of meaning which could be characterized as the part that is common to all other accounts of meaning, and can be captured in mechanical inference rules.

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RDF Primer

RDF Primer: "The Resource Description Framework (RDF) is a language for representing information about resources in the World Wide Web. It is particularly intended for representing metadata about Web resources, such as the title, author, and modification date of a Web page, copyright and licensing information about a Web document, or the availability schedule for some shared resource. However, by generalizing the concept of a 'Web resource', RDF can also be used to represent information about things that can be identified on the Web, even when they cannot be directly retrieved on the Web. Examples include information about items available from on-line shopping facilities (e.g., information about specifications, prices, and availability), or the description of a Web user's preferences for information delivery.

RDF is intended for situations in which this information needs to be processed by applications, rather than being only displayed to people. RDF provides a common framework for expressing this information so it can be exchanged between applications without loss of meaning. Since it is a common framework, application designers can leverage the availability of common RDF parsers and processing tools. The ability to exchange information between different applications means that the information may be made available to applications other than those for which it was originally created."

OWL Web Ontology Language Use Cases and Requirements

OWL Web Ontology Language Use Cases and Requirements: "The Semantic Web is a vision for the future of the Web in which information is given explicit meaning, making it easier for machines to automatically process and integrate information available on the Web. The Semantic Web will build on XML's ability to define customized tagging schemes [XML] and RDF's flexible approach to representing data [RDF Concepts]. The next element required for the Semantic Web is a web ontology language which can formally describe the semantics of classes and properties used in web documents. In order for machines to perform useful reasoning tasks on these documents, the language must go beyond the basic semantics of RDF Schema [RDF Vocabulary].

This document is one part of the specification of OWL, the Web Ontology Language. The Document Roadmap section of the OWL Overview document describes each of the other documents. This document enumerates the requirements of a web ontology language as perceived by the working group. However, it is expected that future languages will extend OWL, adding, among other things, greater logical capabilities and the ability to establish trust on the Semantic Web."

We motivate the need for a web ontology language by describing six use cases. Some of these use cases are based on efforts currently underway in industry and academia, others demonstrate more long-term possibilities. The use cases are followed by design goals that describe high-level objectives and guidelines for the development of the language. These design goals will be considered when evaluating proposed features. The section on Requirements presents a set of features that should be in the language and gives motivations for those features. The Objectives section describes a list of features that might be useful for many use cases but may not necessarily be addressed by the working group.

OWL Web Ontology Language Test Cases

OWL Web Ontology Language Test Cases: "As part of the definition of the Web Ontology Language (OWL) the Web Ontology Working Group provides a set of test cases. This document presents those test cases. They are intended to provide examples for, and clarification of, the normative definition of OWL found in [OWL Semantics and Abstract Syntax] to which this document is subsidiary.

This document is one component of the description of OWL, the Web Ontology Language, being produced by the W3C Web Ontology Working Group. The Document Roadmap section of the [OWL Overview] describes each of the different parts and how they fit together.

This document describes the various types of test used and the format in which the tests are presented. Alternative formats of the test collection are provided. These are intended to be suitable for use by OWL developers in test harnesses, possibly as part of a test driven development process, such as Extreme Programming [XP]. The format of the Manifest files used as part of these alternative formats is described."

XML.com: An Introduction to FOAF

XML.com: An Introduction to FOAF: "The FOAF ('Friend of a Friend') project is a community driven effort to define an RDF vocabulary for expressing metadata about people, and their interests, relationships and activities. Founded by Dan Brickley and Libby Miller, FOAF is an open community-lead initiative which is tackling head-on the wider Semantic Web goal of creating a machine processable web of data. Achieving this goal quickly requires a network-effect that will rapidly yield a mass of data. Network effects mean people. It seems a fairly safe bet that any early Semantic Web successes are going to be riding on the back of people-centric applications. Indeed, arguably everything interesting that we might want to describe on the Semantic Web was created by or involves people in some form or another. And FOAF is all about people."

OWL Web Ontology Language Reference

OWL Web Ontology Language Reference: "This document gives a systematic, compact and informative description of all the modelling primitives of OWL, using the RDF/XML exchange syntax for OWL. We expect this document to serve as a reference guide for users of the OWL language.

This document is one component of the description of OWL, the Web Ontology Language, being produced by the W3C Web Ontology Working Group. The Document Roadmap section of the OWL Overview document describes each of the different parts and how they fit together. Readers unfamiliar with OWL may wish to first consult the OWL Overview document [OWL Overview], and subsequently the OWL Guide [OWL Guide] for a more narrative description and examples of the use of the language.

This document assumes the reader is familiar with the basic concepts of RDF [RDF Concepts] and has a working knowledge of the RDF/XML syntax [RDF/XML Syntax] and of RDF Schema [RDF Vocabulary].

The normative reference on the precise syntax of the OWL language constructs can be found in the OWL Semantics and Abstract Syntax document [OWL S&AS]. That document also contains a precise definition of the meaning of the language constructs in the form of a model-theoretic semantics. Notions such as consistency of OWL ontologies are discussed in that document."

OWL Web Ontology Language Guide

OWL Web Ontology Language Guide: "'Tell me what wines I should buy to serve with each course of the following menu. And, by the way, I don't like Sauternes.'

It would be difficult today to construct a Web agent that would be capable of performing a search for wines on the Web that satisfied this query. Similarly, consider actually assigning a software agent the task of making a coherent set of travel arrangements. (For more use cases see the OWL requirements document.)

To support this sort of computation, it is necessary to go beyond keywords and specify the meaning of the resources described on the Web. This additional layer of interpretation captures the semantics of the data.

The OWL Web Ontologoy Language is a language for defining and instantiating Web ontologies. Ontology is a term borrowed from philosophy that refers to the science of describing the kinds of entities in the world and how they are related. An OWL ontology may include descriptions of classes, properties and their instances. Given such an ontology, the OWL formal semantics specifies how to derive its logical consequences, i.e. facts not literally present in the ontology, but entailed by the semantics. These entailments may be based on a single document or multiple distributed documents that have been combined using defined OWL mechanisms."

OWL Web Ontology Language Overview

OWL Web Ontology Language Overview: "The OWL Web Ontology Language is designed for use by applications that need to process the content of information instead of just presenting information to humans. OWL facilitates greater machine interpretability of Web content than that supported by XML, RDF, and RDF Schema (RDF-S) by providing additional vocabulary along with a formal semantics. OWL has three increasingly-expressive sublanguages: OWL Lite, OWL DL, and OWL Full.

This document is written for readers who want a first impression of the capabilities of OWL. It provides an introduction to OWL by informally describing the features of each of the sublanguages of OWL. Some knowledge of RDF Schema is useful for understanding this document, but not essential. After this document, interested readers may turn to the OWL Guide for more detailed descriptions and extensive examples on the features of OWL. The normative formal definition of OWL can be found in the OWL Semantics and Abstract Syntax."