- From: Jeff Heflin <heflin@cse.lehigh.edu>
- Date: Sat, 16 Feb 2002 15:57:52 -0500
- To: Leo Obrst <lobrst@mitre.org>
- CC: Deborah McGuinness <dlm@ksl.stanford.edu>, Ludger van Elst <elst@dfki.uni-kl.de>, www-webont-wg@w3.org
Leo, Deborah, Ludger, et al. Thanks for the input on definitions of ontologies. While I agree that Gruber's work was seminal, his classic definition "an ontology is an explicit specification of a conceptualization" just confuses most people, including many computer scientists. Given the intended audience of this document, I think such a definition would be a mistake. I think Leo's description is the right level, and will add it to the document. ACTION: Add (with some editing) Leo's "What is an ontology" text from below to the requirements document. Jeff Leo Obrst wrote: > > One of the problems in general is that these definitions are pretty > meaningless to the unenlightened masses. I know: in many venues, I've > had to tamp/dumb down (this is not really pejorative: why expect anyone > outside our community to know the details?) the definition/exposition of > what an ontology is and why is it useful. This is as true in business as > it is in government. > > A paraphrase of my usual spiel (with parenthetical comments bracketed) > at the ontology-naive level: > > --- > What's an Ontology? > > An ontology defines the common words and concepts (meanings) used to > describe and represent an area of knowledge. Ontologies are used by > people, databases, and applications that need to share domain > information (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. They encode knowledge in a domain and also knowledge that spans > domains. So, they make that knowledge reusable. > > An ontology includes the following kinds of concepts: > · Classes (general things) in the many domains of interest > · Instances (particular things) > · The relationships among those things > · The properties (and property values) of those things > · The functions of and processes involving those things > · Constraints on and rules involving those things > > [I usually give an example here of an ontology which has the above > items, in an English quasi-logical form.] > > Ontologies are usually expressed in a logic-based language, so that > fine, accurate, consistent, sound, and meaningful distinctions can be > made among the classes, instances, properties, attributes, and > relations. Some ontology tools can perform automated reasoning using the > ontologies, and thus provide advanced services to intelligent > applications such as: conceptual/semantic search and retrieval > (non-keyword based), software agents, decision support, speech and > natural language understanding, knowledge management, intelligent > databases, and electronic commerce. > > One way to look at ontologies is as metadata schema (metadata is just > data about data, mostly about its content; a schema is just a blueprint > for particular data), that is, a way of structuring and representing the > semantics (meaning) for metadata elements. What is normally known as an > ontology can range from the simple notion of a Taxonomy (knowledge with > minimal hierarchic or parent/child structure), to a Thesaurus (words and > synonyms), to a Conceptual Model (with more complex knowledge), to a > Logical Theory (with very rich, complex, consistent, meaningful > knowledge). > > [I introduce the notion of 'metadata', which many audiences have some > familiarity with, and relate it in simple terms to 'database schema', > which they may also have some knowledge of. I also sketch what I call > the "Ontology Spectrum", a way of relating notions such as 'taxonomy', > 'thesaurus', 'conceptual model', 'logical theory' in an ascending way so > that naive audiences can relate what they know to the bigger picture of > what 'ontologies' are all about.] > > Ontologies figure prominently in the emerging "Semantic Web" as a way of > representing the semantics of documents and enabling the semantics to be > used by web applications and intelligent agents. > Ontologies can prove very useful for a community as a way of structuring > and defining the meaning of the metadata terms that are currently being > collected and standardized. Using ontologies, tomorrow's applications > can be "intelligent", in the sense that they can more accurately work at > the human conceptual level. > --- > > Hope this helps some, > Leo > > Deborah McGuinness wrote: > > > > I also typically refer to Gruber's definition when I introduce ontologies - > > I think citing his work is important. > > When i introduce ontologies to people unfamiliar with our field, I also > > think it is useful to mention that ontology has been around in the > > philosophical literature for a long time and our definition departs from > > theirs. > > I also typically point to collections of work on ontologies, e.g., fois > > books. > > > > I wrote a paper on Ontologies Come of Age[1], which could be one of the > > things pointed to if you like and of course it points to much previous work. > > > > [1] > > http://www.ksl.stanford.edu/people/dlm/papers/ontologies-come-of-age-abstract.html > > > > d > > Ludger van Elst wrote: > > > > > Hi Webont-Members, > > > > > > > "what is an ontology?" stuff in requirements abstract/intro > > > > From: Dan Connolly <connolly@w3.org> > > > ... > > > > let's > > > > see if there's some text to grab... yes: > > > > > > > > Put simply, an ontology is just a set of > > > > standard vocabularly terms along with some > > > > formal definitions of the terms. > > > > > > > > Lightly edited: > > > > > > > > An ontology is vocabularly of terms along > > > > with some formal definitions of the terms. > > > > > > I am a little bit surprised that - though nearly all papers about > > > ontologies refer to Tom Gruber´s "shared conceptualization" definition - > > > all proposals in this group only capture the "conceptualization" aspect > > > but don´t mention the "sharing" aspect. > > > In the requirements document there is a paragraph titled "3.1 Shared > > > Ontologies" which would - accepting Tom's definition - expand to "3.1 > > > Shared Shared Conceptualizations". > > > In my opinion, a good definition of the term ontology should cover both > > > aspects, sharing and conceptualizing. Otherwise, we should consequently > > > only talk about conceptualizations (e.g., "A conceptualization is > > > vocabularly of terms along with some formal definitions of the terms."), > > > not ontologies. > > > > > > What do you think about this topic? > > > > > > Best regards, > > > Ludger > > > > > > ______________________________________________________________________ > > > Ludger van Elst > > > Deutsches Forschungszentrum für Künstliche Intelligenz GmbH > > > Erwin-Schrödinger-Straße Geb. 57/377, D-67608 Kaiserslautern, Germany > > > Tel. : 0631 205-3474 > > > E-mail: elst@dfki.uni-kl.de > > > WWW : http://www.dfki.uni-kl.de/~elst/ > > > ______________________________________________________________________ > > > > -- > > Deborah L. McGuinness > > Knowledge Systems Laboratory > > Gates Computer Science Building, 2A Room 241 > > Stanford University, Stanford, CA 94305-9020 > > email: dlm@ksl.stanford.edu > > URL: http://ksl.stanford.edu/people/dlm > > (voice) 650 723 9770 (stanford fax) 650 725 5850 (computer fax) 801 > > 705 0941 > > -- > _____________________________________________ > Dr. Leo Obrst The MITRE Corporation > mailto:lobrst@mitre.org Intelligent Information Management/Exploitation > Voice: 703-883-6770 7515 Colshire Drive, M/S W640 > Fax: 703-883-1379 McLean, VA 22102-7508, USA
Received on Saturday, 16 February 2002 15:57:57 UTC