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Last modified: January 23, 2004
XML and 'The Semantic Web'

[July 31, 2002]   W3C Web Ontology Working Group Releases Working Drafts for OWL Semantic Markup Language.    Three initial working draft documents on 'OWL' have been published by the W3C's Web-Ontology Working Group (WebOnt). OWL is a semantic markup language for publishing and sharing ontologies on the World Wide Web. OWL is derived from the DAML+OIL Web Ontology Language and builds upon the Resource Description Framework. The designers expect that OWL will support the use of automated tools which "can use common sets of terms called ontologies to power services such as more accurate Web search, intelligent software agents, and knowledge management." The OWL Web Ontology Language is being designed "in order to provide a language that can be used for applications that need to understand the content of information instead of just understanding the human-readable presentation of content. OWL facilitates greater machine readability of web content than XML, RDF, and RDF-S support by providing an additional vocabulary for term descriptions." The Feature Synopsis for OWL Lite and OWL introduces the OWL language. The OWL Web Ontology Language 1.0 Reference provides a systematic, compact and informal description of all the modelling primitives of OWL. An OWL knowledge base is a collection of RDF triples as defined in the RDF/XML Syntax Specification; OWL prescribes a specific meaning for triples that use the OWL vocabulary. The Language Reference document specifies which collections of RDF triples constitute the OWL vocabulary and what the prescribed meaning of such triples is. The OWL Web Ontology Language 1.0 Abstract Syntax document describes a high-level, abstract syntax for both OWL and OWL Lite, a subset of OWL; it also provides a mapping from the abstract syntax to the OWL exchange syntax. [Full context]

[March 08, 2002]   W3C Publishes Web Ontology Language Requirements Document.    The W3C Web Ontology Working Group has published an initial working draft document outlining requirements for the Ontology Web Language (OWL) 1.0 specification. The draft document "specifies usage scenarios, goals and requirements for a web ontology language. Automated tools can use common sets of terms called ontologies to power services such as more accurate Web search, intelligent software agents, and knowledge management." An 'ontology' in terms of the WG charter "defines the terms used to describe and represent an area of knowledge. Ontologies are used by people, databases, and applications that need to share domain information, where a domain is just a specific subject area or area of knowledge, like medicine, tool manufacturing, real estate, automobile repair, financial management, etc. Ontologies include computer-usable definitions of basic concepts in the domain and the relationships among them... An ontology formally defines a common set of terms that are used to describe and represent a domain. The WD specification motivates 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." [Full context]

[February 09, 2001] Semantic Web Activity Launched by W3C. On February 09, 2001, The World Wide Web Consortium formally inaugurated a Semantic Web Activity within the W3C Technology and Society Domain. The 'Semantic Web' is "a vision: the idea of data on the Web defined and linked in a way that it can be used by machines for automation, integration and reuse. The Web can reach its full potential only if it becomes a place where data can be shared and processed by automated tools as well as by people." Part of this vision is "developing an environment to permit each user to make the best use of the resources available on the Web." The Semantic Web Activity is being launched as a successor to the W3C Metadata Activity. Key participants in the new activity include, in addition to W3C Director Tim Berners-Lee, (1) "Eric Miller (W3C, Activity lead), (2) Ralph Swick (W3C, Development Lead), (3) Dan Brickley (University of Bristol, RDF IG Chair and RDF Core WG co-chair) and (4) Brian McBride (HP, RDF Core WG co-chair). Planned activities of W3C toward development of the Semantic Web vision are described in the W3C Semantic Web Activity Statement. We read: "For the Web to scale, programs must be able to share and process data even when these programs have been designed totally independently. The Web can reach its full potential only if it becomes a place where data can be shared and processed by automated tools as well as by people. The Semantic Web Activity, to this end, has been established to serve a leadership role, in both the design of enabeling specifications and the open, collaborative development of technolgies that support the automation, integration and reuse of data across various applications. To faciliate this goal, the Semantic Web Activity builds upon the existing foundation work accomplished by W3C Metadata Activity with the following additional objectives: (1) Continue the work of the RDF Interest Group. The RDF Interest Group will coordinate implementation and deployment of RDF and will provide liaison with new work in the W3C and the wider community on matters relating to RDF. (2) Undertake revisions to the RDF Model and Syntax Recommendation. (3) Complete work on the RDF Schema specification. This Working Group group will incorporate the results of the on-going RDF implementation experience and consider directions established by the XML Schema Candidate Recommendation. (4) Coordinate with W3C initiatives focussed on defining semantics for supporting Web technologies. This includes P3P, CC/PP, XML Protocols, WAI, and other infrastructure for remote services. (5) Coordinate with selected non-W3C initiatives and individual activities working on Semantic Web technologies. This coordination includes, but is not limited to, DCMI, DAML, OIL, SHOE. The current international collaboration between DAML and OIL groups on a Web ontology layer is expected to become a part of this W3C activity. The goals of coordination are to ensure the generality of the solution, to provide solutions and experience, to prevent arbitrary divergence, and to ease adoption of the technology in related fields. (6) Perform advanced development to design and develop supporting XML and RDF technologies. The development project is intended to facilitate distributed collaboration with a specific intent to increase the level of automation of the W3C Web site and to develop open-source RDF infrastructure support modules."

[April 11, 2001] "The Semantic Web. A new form of Web content that is meaningful to computers will unleash a revolution of new possibilities." By Tim Berners-Lee, James Hendler, and Ora Lassila. In Scientific American Volume 284, Number 5 (May, 2001), pages 34-43. Cover story title: 'Get the Idea? Tomorrow's Web Will.' "Most of the Web's content today is designed for humans to read, not for computer programs to manipulate meaningfully. Computers can adeptly parse Web pages for layout and routine processing -- here a header, there a link to another page -- but in general, computers have no reliable way to process the semantics: this is the home page of the Hartman and Strauss Physio Clinic, this link goes to Dr. Hartman's curriculum vitae. The Semantic Web will bring structure to the meaningful content of Web pages, creating an environment where software agents roaming from page to page can readily carry out sophisticated tasks for users. Such an agent coming to the clinic's Web page will know not just that the page has keywords such as 'treatment, medicine, physical, therapy' (as might be encoded today) but also that Dr. Hartman works at this clinic on Mondays, Wednesdays and Fridays and that the script takes a date range in yyyy-mm-dd format and returns appointment times. And it will 'know' all this without needing artificial intelligence on the scale of 2001's Hal or Star Wars's C-3PO. Instead these semantics were encoded into the Web page when the clinic's office manager (who never took Comp Sci 101) massaged it into shape using off-the-shelf software for writing Semantic Web pages along with resources listed on the Physical Therapy Association's site. The Semantic Web is not a separate Web but an extension of the current one, in which information is given well-defined meaning, better enabling computers and people to work in cooperation. The first steps in weaving the Semantic Web into the structure of the existing Web are already under way. In the near future, these developments will usher in significant new functionality as machines become much better able to process and 'understand' the data that they merely display at present... Two important technologies for developing the Semantic Web are already in place: eXtensible Markup Language (XML) and the Resource Description Framework (RDF). XML lets everyone create their own tags -- hidden labels such as or that annotate Web pages or sections of text on a page. Scripts, or programs, can make use of these tags in sophisticated ways, but the script writer has to know what the page writer uses each tag for. In short, XML allows users to add arbitrary structure to their documents but says nothing about what the structures mean . Meaning is expressed by RDF, which encodes it in sets of triples, each triple being rather like the subject, verb and object of an elementary sentence. These triples can be written using XML tags. In RDF, a document makes assertions that particular things (people, Web pages or whatever) have properties (such as 'is a sister of,' 'is the author of') with certain values (another person, another Web page). This structure turns out to be a natural way to describe the vast majority of the data processed by machines. Subject and object are each identified by a Universal Resource Identifier (URI), just as used in a link on a Web page. (URLs, Uniform Resource Locators, are the most common type of URI.) The verbs are also identified by URIs, which enables anyone to define a new concept, a new verb, just by defining a URI for it somewhere on the Web... this is not the end of the story, because two databases may use different identifiers for what is in fact the same concept, such as zip code. A program that wants to compare or combine information across the two databases has to know that these two terms are being used to mean the same thing. Ideally, the program must have a way to discover such common meanings for whatever databases it encounters. A solution to this problem is provided by the third basic component of the Semantic Web, collections of information called ontologies. 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... The real power of the Semantic Web will be realized when people create many programs that collect Web content from diverse sources, process the information and exchange the results with other programs; the Semantic Web promotes this synergy: even agents that were not expressly designed to work together can transfer data among themselves when the data come with semantics."

"Semantic Web Enabled Web Services." By Dieter Fensel (University of Innsbruck) and Christoph Bussler (Oracle Corporation). From the Resources Collection of the Semantic Web Services Initiative (SWSI). April 2003. 36 psges (slides). "Web Services will transform the web from a collection of information into a distributed device of computation. In order to reach full potential, appropriate description means for web services need to be developed. For this purpose we developed a full-fledged Web Service Modeling Framework (WSMF) that provides the appropriate conceptual model for developing and describing web services and their composition. The philosophy of WSMF is based on the principle of maximal de-coupling complemented by scalable mediation service. This is a prerequisite for applying semantic web technology for web service discovery, configuration, comparison, and combination. This presentation provides a vision of web service technology, discussing the requirements for making this technology workable, and sketching the Web Service Modeling Framework..." See also the earlier (2002) paper "The Web Service Modeling Framework WSMF" by the same authors. The Semantic Web Services Initiative (SWSI) is "an ad hoc initiative of academic and industrial researchers, many of which are involved in DARPA and EU funded research projects. The SWSI mission is threefold: (1) to create infrastructure that combines Semantic Web and Web Services technologies to enable maximal automation and dynamism in all aspects of Web service provision and use, including (but not limited to) discovery, selection, composition, negotiation, invocation, monitoring and recovery; (2) to coordinate ongoing research initiatives in the Semantic Web Services area; (3) to promote the results of SWSI work to academia and industry..."

[January 25, 2002]   Seminar on Rule Markup Techniques for the Semantic Web.    A one-week seminar on 'Rule Markup Techniques' will be hosted by the Dagstuhl International Conference and Research Center for Computer Science (Wadern, Germany) on February 3-8, 2002. "Rule systems (e.g., extended Horn logics) suitable for the Web, their (XML and RDF) syntax, semantics, tractability/efficiency, and transformation/compilation will be explored. Both derivation rules (which may be evaluated bottom-up as in deductive databases, top-down as in logic programming, or by tabled resolution as in XSB) and reaction rules (also called 'active' or 'event-condition-action' rules), as well as any combinations, will be considered. This 'Rule Markup Techniques' seminar aims at bringing together the classical- and Web-rule communities to cross-fertilize between their foundations, methods, and applications. The long-term goal is a Web-based standard for rules that makes use of, and is also useful to, the classical rule perspective. The seminar is expected to contribute to some open issues of recent proposals such as Notation 3 (N3), DAML-Rules, and the Rule Markup Language (RuleML). Furthermore, by studying issues of combining rules and taxonomies via sorted logics, description logics, or frame systems, the Seminar will also discuss the US-European proposal DAML+OIL. Two particular issues that will be addressed during this seminar are efficient implementation techniques (e.g., via Java-based rule engines) and major exchange applications (e.g., using e-business rules)." Conference organizers include internationally-recognized authorities on rule and agent markup languages: Harold Boley (DFKI Kaiserslautern, Germany), Benjamin Grosof (MIT Sloan School of Management, USA), Said Tabet (Nisus, USA), and Gerd Wagner (Eindhoven University of Technology, The Netherlands). [Full context]

[August 16, 2001]   W3C Web Ontology Working Group Formed to Extend the 'Semantic Reach' of XML/RDF Metadata Efforts.    A posting from Dan Connolly to the W3C 'www-rdf-logic' mailing list announces the formation of a new Web Ontology Working Group within W3C. The Web Ontology (WebOnt) Working Group has been chartered to design a web ontology language "that builds on current web languges that allow the specification of classes and subclasses, properties and subproperties (such as RDFS), but which extends these constructs to allow more complex relationships between entities including: means to limit the properties of classes with respect to number and type, means to infer that items with various properties are members of a particular class, a well-defined model of property inheritance, and similar semantic extensions to the base languages. The web ontology language must support the development and linking of ontologies together, in a web-like manner. The products of this working group must be supported by a formal semantics allowing language designers, tool builders, and other 'experts' to be able to precisely understand the meaning and 'legal' inferences for expressions in the language. The language will use the XML syntax and datatypes whereever possible, and will be designed for maximum compatibility with XML and RDF language conventions." [Full context]

[September 27, 2000] 'The Semantic Web' (a phrase coined by Tim Berners-Lee, as far as I know) serves also as a convenient title for this collection of references to projects that focus upon (markup language) "semantics" in the context of the Internet. Such endeavors move beyond the level of the particular descriptive meta-markup syntax formalized in SGML, and in its first popular application, HTML. SGML's studied disinterest in (and anathematizing of) primitive semantics (datatypes, relations) was arguably a matter of grand equivocation in the name of separating the specification for logical/structural representation from specification of application level processing semantics. HTML's fundamental disregard for the core creedal elements of SGML (hard-coding display semantics directly into the application) contributed equally to the (chaotic, retarded) advance of generalized descriptive markup technologies. Modest efforts to shore up SGML/XML at the semantic level are [Fall 2000] seen in the W3C XML Schema work (viz., XML Schema Part 2: Datatypes) and in several separate work initiatives, some of which are referenced below. See especially the web site for references, and in a parallel vein, "Conceptual Modeling and Markup Languages." Using syntax (without semantics) works, sort-of, in only one case; otherwise, design by syntax is rather like counting on your ten fingers, fully focused upon meter, as a means of writing poetry.

Work Initiatives and Reference Collections

  • The W3C Activity is the most visible industry-based initiative. For extensive references, see Maintained by Stefan Decker (Stanford University). is operated by three research groups: The Onto-Agents and Scalable Knowledge Composition (SKC) Research Group at Stanford University, The Ontobroker-Group at the University of Karlsruhe, and The Protégé Research Group at Stanford University.

  • See: 'Semantic web' initiatives

  • Design Issues. Architectural and philosophical points. By Tim Berners-Lee. The reference list includes several key papers on RDF and 'The Semantic Web'.

  • Semantic Web Development. Web page at W3C.

  • Ontology Interchange Language (OIL)

  • Resource Description Framework (RDF)

  • (XML) Topic Maps

  • XOL - XML-Based Ontology Exchange Language

  • Simple HTML Ontology Extensions (SHOE)

  • XML Belief Network File Format (Bayesian Networks)

  • Predictive Model Markup Language (PMML)

  • Process Interchange Format XML (PIF-XML)

  • DARPA Agent Mark Up Language (DAML)

  • Relational-Functional Markup Language (RFML)

  • Ontology and Conceptual Knowledge Markup Languages

  • Case Based Markup Language (CBML)

  • Artificial Intelligence Markup Language (AIML)

  • "Business Rules Markup Language (BRML)."

  • Business Rules for Electronic Commerce. Project at IBM T.J. Watson Research. See also Business Rules Markup Language and 'Agent Communication Markup Language'.

  • "Description Logics Markup Language (DLML)."

  • Semantic Web resources. Maintained by Jeff Z. Pan (Department of Computer Science, University of Manchester).

  • Self Organizing Maps. Pioneered by Teuvo Kohonen. Used to access the Medline database, for example. See Self-Organized Alerting and Search Services and Google.

  • KBS/Ontology Projects and Groups - References Maintained by Peter Clark

  • 'Semantic Web Agreement Group'

  • [July 16, 2003] "XML Semantics and Digital Libraries." By Allen Renear (University of Illinois at Urbana-Champaign), David Dubin (University of Illinois at Urbana-Champaign), C. M. Sperberg-McQueen (MIT Laboratory for Computer Science), and Claus Huitfeldt (Department for Culture, Language, and Information Technology, Bergen University Research Foundation). Pages 303-305 (with 14 references) in Proceedings of the Third ACM/IEEE-CS Joint Conference on Digital Libraries (JCDL 2003, May 27-31, 2003, Rice Univerersity, Houston, Texas, USA). Session on Standards, Markup, and Metadata. "The lack of a standard formalism for expressing the semantics of an XML vocabulary is a major obstacle to the development of high-function interoperable digital libraries. XML document type definitions (DTDs) provide a mechanism for specifying the syntax of an XML vocabulary, but there is no comparable mechanism for specifying the semantics of that vocabulary -- where semantics simply means the basic facts and relationships represented by the occurrence of XML constructs. A substantial loss of functionality and interoperability in digital libraries results from not having a common machine-readable formalism for expressing these relationships for the XML vocabularies currently being used to encode content. Recently a number of projects and standards have begun taking up related topics. We describe the problem and our own project... Our project focuses on identifying and processing actual document markup semantics, as found in existing document markup languages, and not on developing a new markup language for representing semantics in general... XML semantics in our sense refers simply to the facts and relationships expressed byXML markup. It does not refer to processing behavior, machine states, linguistic meaning, business logic, or any of the other things that are sometimes meant by 'semantics'. [For example:] (1) Propagation: Often the properties expressed by markup are understood to be propagated, according to certain rules, to child elements. For instance, if an element has the attribute specification lang='de', indicating that the text is in German, then all child elements have the property of being in German, unless the attribution is defeated by an intervening reassignment. Language designers, content developers, and software designers all depend upon a common understanding of such rules. But XML DTDs provide no formal notation for specifying which attributes are propagated or what the rules for propagation are. (2) Class Relationships and Synonymy: XML itself contains no general constructs for expressing class membership or hierarchies among elements, attributes, or attribute values -- one of the most fundamental relationships in contemporary information modeling. (3) Ontological variation in reference: XML markup might appear to indicate that the same thing, is-a-noun, is-a-French-citizen, is-illegible, has-been-copyedited; but obviously either these predicates really refer to different things, or must be given non-standard interpretations. (4) Parent/Child overloading: The parent/child relations of the XML tree data structure support a variety of implicit substantive relationships... These examples demonstrate several things: what XML semantics is, that it would be valuable to have a system for expressing XML semantics, and that it would be neither trivial nor excessively ambitious to develop such a system. We are not attempting to formalize common sense reasoning in general, but only the inferences that are routinely intended by markup designers, assumed by content developers, and inferred by software designers... The BECHAMEL Markup Semantics Project led by Sperberg-McQueen (W3C/MIT) grew out of research initiated by in the late 1990s and is a partnership with the research staff and faculty at Bergen University (Norway) and the Electronic Publishing Research Group at the University of Illinois. The project explores representation and inference issues in document markup semantics, surveys properties of popular markup languages, and is developing a formal, machine-readable declarative representation scheme in which the semantics of a markup language can be expressed. This scheme is applied to research on information retrieval, document understanding, conversion, preservation, and document authentication. An early Prolog inferencing system has been developed into a prototype knowledge representation workbench for representing facts and rules of inference about structured documents."

  • [November 22, 2002] "The Myths of 'Standard' Data Semantics. Faulty Assumptions Must Be Rooted Out." By William C. Burkett (Senior Information Engineer, PDIT). In XML Journal Volume 3, Issue 11 (November 2002). "Much of the literature heralding the benefits of XML has focused on its application as a medium for application interoperability. With (a) the Internet as a platform, (b) Web services as the functional building block components of an orchestrated application, and (c) XML as a common data format, applications will be able to communicate and collaborate seamlessly and transparently, without human intervention. All that's needed to make a reality is (d) for everyone to agree on and use XML tags the same way so that when an application sees a tag such as <firstName> it will know what it means. This intuitive understanding makes a lot of sense, which is why so many organizations have sprung into existence to create their own vocabularies (sets of tags) to serve as the 'lingua franca for data exchange in <insert your favorite industry, application, or domain>.' This intuitive understanding is so pervasive that it's even a key part of the U.S. GAO recommendations to Senator Joseph Leiberman (chairman of the Committee on Governmental Affairs, U.S. Senate) on the application of XML in the federal government. This report warns of the risk that: <q>...markup languages, data definitions, and data structures will proliferate. If organizations develop their systems using unique, nonstandard data definitions and structures, they will be unable to share their data externally without providing additional instructions to translate data structures from one organization and system to another, thus defeating one of XML's major benefits.</q>. The perspective of these efforts is that the standardization and promotion of the data element definitions and standard data vocabularies (SDV) will solve the application interoperability problem. Unfortunately, this intuitive understanding -- like many intuitive understandings -- doesn't survive the trials of real-life application because important (and seemingly trivial) assumptions are poorly conceived. This article will examine some of these assumptions and articulate several myths of 'standard' data semantics. The notion that data semantics can be standardized through the creation and promulgation of data element names/definitions or vocabularies is based on several assumptions that are actually myths: [1] Myth 1: Uniquely named data elements will enable, or are enough for, effective exchange of data semantics (i.e., information). [2] Myth 2: Uniquely named data elements will be used consistently by everybody to mean the same thing. [3] Myth 3: Uniquely named data elements can exist -- uniquely named as opposed to uniquely identified data elements. Many will readily acknowledge that these are, in fact, myths and that they don't really hold these assumptions. However, it seems that users of namespaces and developers of SDVs and metadata registries are pursuing their work as if these assumptions were true. No mechanisms or strategies have appeared in the extant literature that acknowledge, explain, or address the challenges that arise due to these faulty assumptions. The reasons that these assumptions are faulty fall into the following three areas of SDV development and use: (1) Scope, (2) Natural language use, and (3) Schema evolution... The purpose of this article hasn't been to argue that the problems and the challenges that face the SDV/registry development projects are unsolvable. Rather, it is to suggest that the solution vision must be more expansive. Faulty assumptions must be rooted out, and the problems that are thereby exposed must be explicitly and directly addressed. Despite their intuitive appeal, namespaces, SDVs, registries, and unique data element names will not solve the problem of interoperability. What's needed is the recognition that the semantics of a schema (or, more precisely, the semantics of data governed by a schema) must be explicitly bound to a known community that it serves, and that bridges between the communities will be an inevitable part of any comprehensive solution..." [alt URL]

  • [November 11, 2002] "Ontology Building: A Survey of Editing Tools." By Michael Denny (Northport, NY). 2002-11-11. Posted by request. "I have just completed a general survey of ontology editing software for building ontologies. I am preparing a short report of perhaps 1,500 words that summarizes the use of ontologies in IT solutions to accompany the tabulated findings of the survey. Approximately 50 editing tools were identified and described concisely in 12 categories using editorial input from the tools' suppliers. I believe this represents the largest number of ontology editors ever compiled. While ontologies have a close association with RDF and the Semantic Web, they do not necessarily rely on XML or even Web applications. But the trend in knowledge technology is toward a unification based on XML and the Web..." See following reference. Admin note 2004-01-23: see the more recent version at

  • [November 11, 2002] "Ontology Building: A Survey of Editing Tools." By Michael Denny. From November 06, 2002. ['Earlier this year at the WWW2002 conference, there was a surprisingly strong interest in ontologies--structured models of known facts. Ontologies have come out of the research labs and into common use for modeling complex information. Our main feature this week is a survey of tools available for editing ontologies. As part of his survey Michael Denny also provides a great introduction to what ontologies are, how they vary, and how they are constructed.'] "The semantic structuring achieved by ontologies differs from the superficial composition and formatting of information (as data) afforded by relational and XML databases. With databases virtually all of the semantic content has to be captured in the application logic. Ontologies, however, are often able to provide an objective specification of domain information by representing a consensual agreement on the concepts and relations characterizing the way knowledge in that domain is expressed. This specification can be the first step in building semantically-aware information systems to support diverse enterprise, government, and personal activities...In the Semantic Web vision, unambiguous sense in a dialog among remote applications or agents can be achieved through shared reference to the ontologies available on the network, albeit an always changing combination of upper level and domain ontologies. We just have to assume that each ontology is consensual and congruent with the other shared ontologies (e.g., ontologies routinely include one another). The result is a common domain of discourse that can be interpreted further by rules of inference and application logic. Note that ontologies put no constraints on publishing (possibly contradictory) information on the Web, only on its (possible) interpretations... The wide array of information residing on the Web has given ontology use an impetus, and ontology languages increasingly rely on W3C technologies like RDF Schema as a language layer, XML Schema for data typing, and RDF to assert data... The 'Survey of Ontology Editors' covers software tools that have ontology editing capabilities and are in use today. The tools may be useful for building ontology schemas (terminological component) alone or together with instance data. Ontology browsers without an editing focus and other types of ontology building tools are not included. Otherwise, the objective was to identify as broad a cross-section of editing software as possible. The editing tools are not necessarily production level development tools, and some may offer only limited functionality and user support. Concise descriptions of each software tool were compiled and then reviewed by the organization currently providing the software for commercial, open, or restricted distribution. The descriptions are factored into a dozen different categories covering important functions and features of the software... Despite the immaturity of the field, we were able to identify a surprising number of ontology editors -- about 50 overall..." See preceding entry.

  • [October 31, 2002] "Ontologies Come of Age." By Deborah L. McGuinness (Associate Director and Senior Research Scientist, Knowledge Systems Laboratory, Stanford University, Stanford, CA, USA). [WWW] Published in Spinning the Semantic Web: Bringing the World Wide Web to Its Full Potential [edited by Dieter Fensel, Jim Hendler, Henry Lieberman, and Wolfgang Wahlster; MIT Press, 2002]. "Ontologies have moved beyond the domains of library science, philosophy, and knowledge representation. They are now the concerns of marketing departments, CEOs, and mainstream business. Research analyst companies such as Forrester Research report on the critical roles of ontologies in support of browsing and search for e-commerce and in support of interoperability for facilitation of knowledge management and configuration. One now sees ontologies used as central controlled vocabularies that are integrated into catalogues, databases, web publications, knowledge management applications, etc. Large ontologies are essential components in many online applications including search (such as Yahoo and Lycos), e-commerce (such as Amazon and eBay), configuration (such as Dell and PC-Order), etc. One also sees ontologies that have long life spans, sometimes in multiple projects (such as UMLS, SIC codes, etc.). Such diverse usage generates many implications for ontology environments. In this paper, we will discuss ontologies and requirements in their current instantiations on the web today. We will describe some desirable properties of ontologies. We will also discuss how both simple and complex ontologies are being and may be used to support varied applications. We will conclude with a discussion of emerging trends in ontologies and their environments and briefly mention our evolving ontology evolution environment..."

  • [October 16, 2002] "XML and the Semantic Web. It's Time to Stop Squabbling -- They're Not Incompatible." By Jim Hendler and Bijan Parsia (University of Maryland). In XML Journal Volume 03, Issue 10 (October 2002). "... Every Web link is an often vague, usually ambiguous, and almost always underspecified assertion about the things it connects. RDF lets us eliminate that vagueness and nail down the ambiguity. RDF Schema (RDFS) and the new Web Ontology Language (OWL) allow us to model the meaning of our assertion links in precise, machine-processible ways. RDFS is a simple language for creating Web-based "controlled vocabularies" and taxonomies. The language defines several RDF predicates for making links between concepts. Most notably, RDFS defines class and property relations and provides a mechanism for restricting the domains and ranges of the properties. In RDFS, for example, we can express site-specific Yahoo-like Web site categories as a hierarchy of classes with sets of named (sometimes inherited) properties. This allows other sites to connect their own information to these terms, providing better interoperability for use in B2C, B2B, or other Web transactions... The Semantic Web is being built on models based on the RDF representation of Web links. To achieve their full impact, however, the enhanced models enabled by the Semantic Web crucially need to be tied to the document-processing and data-exchange capabilities enabled by the spread of XML technologies. If XML- and RDF-based technologies were incompatible, as some people seem to think they are, it would be a true shame. But, in fact, they aren't. While the underlying models are somewhat different, the normative document exchange format for RDF, RDFS, and OWL is XML. Thus, to those preferring to think of the whole world as XML based, RDF, RDFS, and OWL may simply be thought of as yet another XML language to be managed and manipulated using the standard toolkit. To the RDF purist, the documents and datasets being expressed in XML and XML Schema can anchor their models with interoperable data. To those focused on the world of Web services, SOAP and WSDL can carry, in their XML content, RDF models expressing information that can be easily found, linked, and discovered. Of course, as is the case with any groups doing overlapping tasks, there is friction between some in the RDF community and some in the XML world. RDF folks often complain about the (for them) superfluous intricacies of XML. XML experts shake their heads at the way the RDF/XML serialization abuses QNames and XML Namespaces and treats certain attributes and child elements as equivalent. However, these kinds of complaints are nothing new. In fact, they're common in the XML community itself: witness the fury that some XML people express over XSLT's use of QNames as attribute content (to pick one example). Similarly, the RDF world has plenty of dark and overcomplicated corners. Both sets of languages are also continuing to evolve, and each is also exploring new non-XML syntaxes (consider Relax-NG, XQuery, and XPath)... The Semantic Web offers powerful new possibilities and a revolution in function. These capabilities will arrive sooner if we stop squabbling and realize that the rift between XML- and the RDF-based languages is now down to the minor sorts of technical differences easily ironed out in the standards process or kludged by designing interoperable tools..." [alt URL]

  • [September 06, 2002] "Weaving A Web of Ideas. Engines that search for meaning rather than words will make the Web more manageable." By Steven M. Cherry. In IEEE Spectrum Online (September 2002). "... If we couldn't build intelligent software agents to navigate a simplistic Web, can we really build intelligence into the 3 billion or 10 billion documents that make up the Web? ... The first step is to get a fulcrum under the mountain and lift it, and it is well under way. That fulcrum is the extensible markup language (XML)... XML builds on a second fundamental Web technique: coding elements in a document... The resource description framework (RDF) is the third component of the Semantic Web. An RDF makes it possible to relate one URI to another. It is a sort of statement about entities, often expressing a relation between them. An RDF might express, for example, that one individual is the sister of another, or that a new auction bid is greater than the current high offer. Ordinary statements in a language like English can't be understood by computers, but RDF-based statements are computer-intelligible because XML provides their syntax -- marks their parts of speech, so to speak... The Semantic Web notion that ties all the others together is that of an ontology -- a collection of related RDF statements, which together specify a variety of relationships among data elements and ways of making logical inferences among them. A genealogy is an example of an ontology. The data elements consist of names, the familial relationships... 'Syntax,' 'semantics,' and 'ontology' are concepts of linguistics and philosophy. Yet their meanings don't change when used by the theorists in the Semantic Web community. Syntax is the set of rules or patterns according to which words are combined into sentences. Semantics is the meaningfulness of the terms -- how the terms relate to real things. And an ontology is an enumeration of the categories of things that exist in a particular universe of discourse (or the entire universe, for philosophers)... Valuable as the Semantic Web might be, it won't replace regular Web searching. Peter Pirolli, a principal scientist in the user interface research group at the Palo Alto Research Center (PARC), notes that usually a Web querier's goal isn't an answer to a specific question. 'Seventy-five percent of the time, people are engaged in what we call sense-making,' Pirolli says. Using the same example as Berners-Lee, he notes that if someone is diagnosed with a medical problem, what a family member does first is search the Web for general information. 'They just want to understand the condition, possible treatments, and so on.' PARC researchers think there's plenty of room for improving Web searches. One method, which they call scatter/gather, takes a random collection of documents and gathers them into clusters, each denoted by a single topic word, such as 'medicine,' 'cancer,' 'radiation,' 'dose,' 'beam.' ... The method works by precomputing a value for every word in the collection in relation to every other word. 'The model is a Bayesian network, which is the same model that's used for describing how long-term memory works in the human brain,' Card says. The current king of the Web search world, Google, doubts the Web will ever be navigable by computers on their own According to this picture of long-term memory (there are others), neurons are linked to one another in a weighted fashion (represented by synapses)... For Autonomy, Bayesian networks are the starting point for improved searches. The heart of the company's technology, which it sells to corporations like General Motors and Ericsson, is a pattern-matching engine that distinguishes different meanings of the same term and so 'understands' them as concepts. Autonomy's system, by noting that the term 'engineer' sometimes occurs in a cluster with others like 'electricity,' 'power,' and 'electronics' and sometimes with 'cement,' 'highways,' and 'hydraulics,' can tell electrical from civil engineers. In a way, Autonomy builds an ontology without XML and RDFs..."

  • [May 07, 2002] "The Languages of the Semantic Web." By Uche Ogbuji. In New Architect Volume 7, Issue 6 (June 2002), pages 30-33. ['If you believe Tim Berners-Lee, the Web has more potential than is realized today. Part of that potential is held in specifications like RDF and DAML+OIL. A new Web where agents do our bidding may not be far off.'] "RDF itself is a handy way to describe resources. Widespread use of such a facility could alleviate many of the current problems with the Web. But RDF by itself only gets us part way toward realizing the Semantic Web, in which agents can infer relationships and act on them. Classification is extremely important on the Semantic Web. Each community of related interests defines categories for the matters that it discusses. For instance, the snowboarding community defines items such as snowboards, parks, tricks, and manufacturers. The definition of a manufacturer in snowboarding terms is related to the definition of a manufacturer in the general business sense. The snowboarding community can enshrine these definitions by creating a schema for its RDF models... The leading ontology system for RDF is the DARPA Agent Markup Language (DAML). DARPA, for those who may have forgotten, is the group that brought us the Internet itself. DAML incorporated useful concepts from the Ontology Inference Layer (OIL), a European project to provide some AI primitives in RDF form. The resulting language is DAML+OIL. DAML+OIL lets us formally express ontologies. W3C RDFS provides primitive classification and simple rules for this, but DAML+OIL goes much further. For instance, DAML+OIL can express that 'any snowboard with plate bindings is a race board,' which makes it unnecessary to then explicitly flag every race board. You might see in this some of the flavor of business rules, which are known in software development circles as the programmatic expression of mandates for the way data must be processed. In fact, one way to look at DAML+OIL is as the business rules for the Semantic Web, yet it's much more flexible than most business-rules-languages in common use. Most of DAML+OIL's power comes from primitives for expressing classifications, as the race boards example illustrates. DAML+OIL provides a toolbox of class expressions, which bring the power of mathematical logic and set theory to the tricky and important task of mapping ontologies through classifications... The Semantic Web is still a way off, if it's attainable at all. To date, RDF and DAML+OIL are our best efforts at reaching it. They address a good number of the problems with the present state of the Web, and further enhancements are on the way. For example, a system of statements that's managed at a certification authority could help establish the validity of RDF statements to minimize metadata spam and other security problems..." See: (1) "DARPA Agent Mark Up Language (DAML)"; (2) "Resource Description Framework (RDF)." [alt URL]

  • [April 08, 2002]   ISO Common Logic Standard Proposed for Use With RDF, UML, DAML, and Topic Maps.    A posting from John Sowa summarizes the results of a recent Common Logic Standardization Meeting held at Stanford University which proposes an ISO Common Logic (CL) Standard related to Knowledge Interchange Format (KIF) and Conceptual Graphs (CGs). CL is to be "defined by an abstract syntax, which specifies the major categories, such as Quantifier, Negation, and Conjunction, without specifying any concrete symbols for writing them. The CL standard will also contain grammars for three concrete syntaxes: KIF, CGIF (the CG interchange format), and traditional predicate calculus (TPC) with a Unicode encoding of the commonly used symbols. Besides the three concrete syntaxes that are currently planned for the standard, [the group] discussed plans for an XML-based syntax [XML-CL] that could be mapped directly to the abstract syntax. For example, the abstract category Conjunction would be expressed differently in each of the three concrete syntaxes. Instead of giving a separate mapping to XML from each of the concrete syntaxes, it would be simpler to map the abstract category directly to the XML form <conjunction>... </conjunction> without specifying which of the three concrete syntaxes was the original source or the intended target of the information." The development team "hopes that the CL standard can be used for many other languages that have a declarative semantics, such as RDF, UML, DAML, or Topic Maps. There will be an XML representation of the abstract categories, which will conform to all accepted W3C standards. There may also be XML representations of the concrete syntaxes as well; TPC notation will require Unicode for the special logical symbols, but they could also be represented, as in HTML and XML, by symbols like &forall; or &exist;." [Full context]

  • [April 09, 2002] "Architectures for Intelligent Systems." By John F. Sowa. Revised version. 2002-04-09 or later. ['I have put a new version of the paper "Architectures for Intelligent Systems" on my web site; the major change from the earlier version is the addition of a new concluding section... At ICCS 2002 in Bulgaria, I'll be giving a tutorial on the topic of designing intelligent systems using conceptual graphs. Some of the material in this paper will be included. In particular, I would like to see an architecture along these lines developed as a project for the entire CG community. Existing systems and components could be incorporated into the project by passing CGIF messages to and from the blackboard. New systems could be designed around the blackboard from the start.'] "People communicate with each other in sentences that incorporate two kinds of information: propositions about some subject, and metalevel speech acts that specify how the propositional information is used -- as an assertion, a command, a question, or a promise. By means of speech acts, a group of people who have different areas of expertise can cooperate and dynamically reconfigure their social interactions to perform tasks and solve problems that would be difficult or impossible for any single individual. This paper proposes a framework for intelligent systems that consist of a variety of specialized components together with logic-based languages that can express propositions and speech acts about those propositions. The result is a system with a dynamically changing architecture that can be reconfigured in various ways: by a human knowledge engineer who specifies a script of speech acts that determine how the components interact; by a planning component that generates the speech acts to redirect the other components; or by a committee of components, which might include human assistants, whose speech acts serve to redirect one another. The components communicate by sending messages to a Linda-like blackboard, in which components accept messages that are either directed to them or that they consider themselves competent to handle... A major advantage of a flexible modular framework is that it doesn't have to be implemented all at once. The four design principles, which enabled Unix-like systems to be implemented on anything from a wearable computer to the largest supercomputers, can also support the growth of intelligent systems from simple beginnings to a large 'society of mind,' as Minsky [1985] called it. For an initial implementation, each of the four principles could be reduced to the barest minimum, but any of them could be enhanced incrementally without disturbing any previously supported operations..."

  • [March 21, 2002]   W3C RDF Core Working Group Publishes RDF Primer Working Draft.    The W3C RDF Core Working Group has produced an initial public working draft RDF Primer. The Resource Description Framework (RDF) is a general-purpose language for representing information 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, the copyright and syndication information about a Web document, the availability schedule for some shared resource, or the description of a Web user's preferences for information delivery. RDF provides a common framework for expressing this information in such a way that 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. Exchanging information between different applications means that the information may be made available to applications other than those for which it was originally created. This Primer is designed to provide the reader the basic fundamentals required to effectively use RDF in their particular applications." [Full context]

  • The Researchgroup Knowledge Management. Institute for Applied Computer Science and Formal Description Methods (AIFB), University of Karlsruhe, Karlsruhe, Germany. See especially the Publications of the Researchgroup Knowledge Management and the OntoBroker Project.

  • IEEE Standard Upper Ontology (SUO) Study Group. "This standard will specify the semantics of a general-purpose upper level ontology. An ontology is a set of terms and formal definitions. This will be limited to the upper level, which provides definition for general-purpose terms and provides a structure for compliant lower level domain ontologies. It is estimated to contain between 1000 and 2500 terms plus roughly ten definitional statements for each term. Is intended to provide the foundation for ontologies of much larger size and more specific scope...The ontology will be suitable for "compilation" to more restricted forms such as XML or database schema. This will enable database developers to define new data elements in terms of a common ontology, and thereby gain some degree of interoperability with other compliant systems."

  • Knowledge Interchange Format (KIF). "Knowledge Interchange Format (KIF) is a computer-oriented language for the interchange of knowledge among disparate programs. It has declarative semantics (i.e., the meaning of expressions in the representation can be understood without appeal to an interpreter for manipulating those expressions); it is logically comprehensive (i.e., it provides for the expression of arbitrary sentences in the first-order predicate calculus); it provides for the representation of knowledge about the representation of knowledge; it provides for the representation of nonmonotonic reasoning rules; and it provides for the definition of objects, functions, and relations." See also the manual, draft proposed standard, and KIF Mailing List.

  • Cyc - "with a common sense". The Cyc product family comprises an immense multi-contextual knowledge base, an efficient inference engine, a set of interface tools, and a number of special-purpose application modules running on Unix, Windows NT, and other platforms. The knowledge base is built upon a core of over 1,000,000 hand-entered assertions (or 'rules') designed to capture a large portion of what we normally consider consensus knowledge about the world. For example, CYC knows that trees are usually outdoors, that once people die they stop buying things, and that glasses of liquid should be carried rightside-up. This foundation enables CYC to understand and reason about its application domains...' See the introduction, publications, and applications.

  • [November 29, 2000] Conversion Tool for DAML-O, RDF Schema, and UML/XMI. A posting from Sergey Melnik and Stefan Decker (Stanford University) announces the availability of an online tool for converting between different data representations. The conversion tool is documented on the Interdataworking web site. This work-in-progress tool features: "(1) support for conversion between DAML-O, RDF Schema, and UML/XMI; (2) translation between quad and built-in reification, representation of order using 'RDF Seq' and 'order-by-reification' mechanisms; (3) support for conversion from Protégé RDF files to DAML-O restrictions; (4) a new XML serializer for RDF (trivial RDF/XML syntax) with support for embedded models and statements." The web site "provides a testbed for the concept of gateways in the 'interdataworking' technology. Interdataworking is a novel software structuring technique that facilitates data exchange between heterogeneous applications. The testbed supports data conversion from one format into another; the source data can be specified using a URL or uploaded as a file from your file system. You can choose a parser for your data. The object model delivered by the parser is sent through a sequence of gateways. The list of gateways can be selected, and the order is important. The result is output using a specified serializer..." Theoretical background may be found in papers written by the developers: (1) "A Layered Approach to Information Modeling and Interoperability on the Web" (Melnik and Decker), and (2) "Representing UML in RDF" (Melnik).

  • "STEP/EXPRESS and XML." ISO/SC4 Project Number 10303-0028 (Implementation methods: XML representation of EXPRESS schemas and data) is one of initiatives which seek to align STEP/EXPRESS specifications with XML and SGML. Development of XML/SGML notations for EXPRESS is desirable because the EXPRESS schema language has rich facilities for data modeling at the semantic level (e.g., an expression sublanguage, semantic constraint mechanisms, aggregate data types [bag, set, list, array] for attribute values, etc). Part 21 of the STEP standard already provides a clear text encoding, but many expect this to be replaced by XML in the future. As of early 2001, the design group had "agreed to start work on an XML Schema binding for EXPRESS data because XML Schema provides a more powerful and flexible constraint language for XML data" [than does XML DTD notation].

  • [February 28, 2002] "XML and UML." By Sean McGrath. In XML In Practice (February 07, 2002). "XML is an increasingly important part of many applications. XML people argue that XML provides its own modeling paradigm -- originally DTDs and, more recently, W3C XML Schema. UML people argue that DTDs and W3C Schema are just notations and that organizations can and should keep their data models independent of any one syntax by using UML diagrams as the normative reference. From the UML diagrams, the story goes, you can *generate* DTDs, W3C Schemas, Relax NG Schemas, whatever you want. Lets pause for breath and think about what is going on here. Syntax (XML) versus semantics (model diagrams). Generating one from the other, keeping your options open by becoming more abstract in your models. There is a word for this phenomenon, actually an acronym. A four-letter acronym: MMTT -- More Meta Than Thou. The MMTT aspect of this worries me. Reason being we have heard it all before. Just one more level and all will be revealed: ISO Seven Layered Model, Ada, Z Notation, Architectural Forms. Will UML go the same way? Another worrying thing is the mismatch between the things UML is happy modeling and the things XML is happy modeling..." [Note: this article seems to take as its vantage point UML software with GUI interfaces and visual display; UML can be understood as more than a specification for drawing tools, 'though much is still lacking to make it a complete modeling language...']

  • [November 29, 2001] "Web Ontology Reasoning in the SHOQ(Dn) Description Logic." By Jeff Z. Pan (Department of Computer Science, University of Manchester). WWW. Presented at the M4M-2 [Methods for Modalities] Workshop, Amsterdam, November 2001. 12 pages (with 12 references). "The Semantic Web is a vision of the next generation Web in which semantic markup will make Web resources more accessible to automatic processes. Ontologies will be key components of the Semantic Web, and it is proposed that Description Logics will provide the formal underpinnings and reasoning services for Web ontology languages. In this paper we will show how one such description logic, SHOQ(D), can be extended with n-ary datatype predicates, to give SHOQ(Dn), and we will present an algorithm for deciding the satisfability of SHOQ(Dn) concepts, along with a proof of its soundness and completeness. The work is motivated by the requirement for n-ary datatype predicates in relation to 'real world' properties such as size, weight and duration, in the Semantic Web applications..."

  • [June 18, 2001] KnoW. "KnoW is a collaborative initiative bringing together industrial, commercial, governmental and not-for-profit organizations, consultants, implementers, academics and software vendors, with the intent of making rapid and tangible progress towards enabling the sharing and exchange of knowledge between people, organizations and systems using the technology of the Web. Projects include (1) The study of relationships between RDF, XTM, NewsML, EXIST, EPISTLE, DAML, OIL, XBRL; (2) Research into the roles of human and machine intelligence in the semantic interoperation of XML vocabularies..." See: "A project is under development within the KnoW (Knowledge on the Web) initiative that will study the relationships, overlaps, differences and complementarities between a number of specifications that are relevant to knowledge on the Web, including Topic Maps, RDF, DAML, EXIST and NewsML. The likely timeframe for this project is the next few months, and the results will be made public..." [Posting from Jay Cousins, 18 Jun 2001]

  • [September 21, 2001] "The Semantic Web: An Introduction." By Sean B. Palmer. ['This document is designed as being a simple but comprehensive introductory publication for anybody trying to get into the Semantic Web: from beginners through to long time hackers. The document discusses many principles and technologies of the Semantic Web, including RDF, RDF Schema, DAML, ontologies, inferences, logic, SEM, queries, trust, proof, and so on. Because it touches a lot of subjects, it may cover some well-known material, but it should also have something that will be of interest to everyone.'] "... So the Semantic Web can be seen as a huge engineering solution... but it is more than that. We will find that as it becomes easier to publish data in a repurposable form, so more people will want to pubish data, and there will be a knock-on or domino effect. We may find that a large number of Semantic Web applications can be used for a variety of different tasks, increasing the modularity of applications on the Web. But enough subjective reasoning... onto how this will be accomplished. The Semantic Web is generally built on syntaxes which use URIs to represent data, usually in triples based structures: i.e., many triples of URI data that can be held in databases, or interchanged on the world Wide Web using a set of particular syntaxes developed especially for the task. These syntaxes are called 'Resource Description Framework' syntaxes... Table Of Contents: 1. What Is The Semantic Web?; 2. Simple Data Modelling: Schemata; 3. Ontologies, Inferences, and DAML; 4. The Power Of Semantic Web Languages; 5. Trust and Proof; 6. Ambient Information and SEM; 7. Evolution; 8. Does It Work? What Semantic Web Applications Are There?; 9. What Now? Further Reading."

  • [October 11, 2000] New area of the electronic journal Electronic Transactions on Artificial Intelligence (ETAI) entitled "The Semantic Web." The new semantic Web area "is concerned with modeling semantics of web information, and covers theory, methods, and applications." See the announcement from Guus Schreiber (Department of Social Science Informatics, University of Amsterdam).

  • Ontology.Org "Ontology.Org is an independent industry and research forum focussed upon the application of ontologies in Internet commerce. It is the central goal of Ontology.Org to use ontologies to address the problems that impact the formation and sustainability of large electronic trading groups."

  • "Components and Structure of a VHG [Virtual Hyperglossary ]." "The components of a termEntry are described formally in the DTD, but the current section is a general introduction for non-terminologists... The VHG relies heavily on the emerging ISO FDIS 12620 standard for data categories in terminology, which describes about 300 categories used by terminologists. Terminology requires great precision in the use of words and phrases and for industrial-strength applications you should be careful to use words in a way that is consistent with FDIS 12620. . . Curators will often wish to add strucure to their VHGs. Thus gas in the scientific sense will often be linked to other terms. These might include latent heat, vapour pressure, critical temperature and many more. To systematise this, the curator of a VHG might create a parent termEntry such as vaporisation. For melting phenomena she might create fusion. To unite both of these she might create an even higer level termEntry, phase change...The creation of such classifications requires a great deal of work, technical, organisational and usually political. Ontologies are highly personal, and there are frequently battles over classifications, taxonomies and related approaches. Often they are dynamic, and may have poorly developed terms." See "Virtual Hyperglossary (VHG)."

  • [December 08, 2000] "Talks: Berners-Lee and the Semantic Web Vision." By Edd Dumbill. From December 06, 2000. ['In a keynote session at XML 2000 Tim Berners-Lee, Director of the World Wide Web Consortium, outlined his vision for the Semantic Web.'] "In a keynote session at XML 2000 Tim Berners-Lee, Director of the Wide Web Consortium, outlined his vision for the Semantic Web. In one of his most complete public expositions of the vision to date, he explained the layered architecture that he foresees being developed in the next ten years. He kicked off by explaining what he means by the two words 'semantic' and 'web.' Underlying the Web was the philosophy of a navigable space, with a mapping from URI to resources. He stressed that a URI was an identifier for a resource, and not a recipe for its retrieval. Berners-Lee said that in the context of the Semantic Web, the word 'semantic' meant 'machine processable.' He explicitly ruled out the sense of natural language semantics. For data, the semantics convey what a machine can do with that data. In the future, Berners-Lee anticipated that they will also enable a machine to figure out how to convert that data, too. He described the 'semantic test,' which is passed if, when you give data to a machine, it will do the right thing with it. He also underlined that the Semantic Web is, like XML, a declarative environment, where you say what you mean by some data, and not what you want done with it... He explained the importance of RDF/RDF Schema as a language for the description of 'things' (resources) and their types. Above this, he described the ontology layer. An ontology is capable of describing relationships between types of things, such as 'this is a transitive property', but does not convey any information about how to use those relationships computationally. On top of the ontology layer sits the logic layer. This is the point at which assertions from around the Web can be used to derive new knowledge. The problem here is that deduction systems are not terribly interoperable. Rather than design one overarching reasoning system, Berners-Lee instead suggests a universal language for representing proofs. Systems can then digitally sign and export these proofs for other systems to use and possibly incorporate into the Semantic Web. Berners-Lee ended his presentation examining what could be done practically today. He observed that the higher layers of his architecture are likely to take around ten years yet to come to fruition -- most of the new work today is happening on ontologies. Practical solutions include the use of XSLT to derive RDF from XML sources, the work on topic maps and RDF convergence, the emergence of general-purpose RDF databases and engines, and general and specific GUIs for RDF data. Berners-Lee noted that a rearrangement of the metadata activity within the W3C would also have a bearing on Semantic Web work." See the slide presentation.

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