- From: Hans Teijgeler <hans.teijgeler@quicknet.nl>
- Date: Thu, 27 Oct 2005 21:48:10 +0200
- To: "'Frank Manola'" <fmanola@acm.org>, "Herman, Ivan" <ivan@w3.org>
- Cc: <semantic-web@w3.org>
- Message-Id: <200510271948.j9RJmBUI000796@vmx60.multikabel.net>
Hi Frank and Ivan, Thank you for your responses! Two opinions, and this poor newbie must make a choice, where he had hoped for a solution: ========================================== Ivan Herman wrote: I think that - if you use OWL Full, then owl:Thing is equivalent to rdf:Resource, you can't be more general than that:-) - if you use OWL DL or Lite, than you *have* to use owl:Thing, this is the way you identify individuals Ie: the safe bet is to use owl:Thing. You do not loose anything and, if at some point you have a smaller ontology that turns out DL or Lite, then you are all set. Just my personal opinion... Ivan ========================================= Frank Manola wrote: Hi Hans-- I'm probably not the most reliable guide on OWL dialects, and I'm not sure I fully understand what you're doing. However, I don't see the need to use owl:Thing explicitly at all. My understanding is, if you create a user-defined OWL class, e.g., <owl:Class rdf:ID="UserDefinedClass"/> or as a triple ex:UserDefinedClass rdf:type owl:Class . then UserDefinedClass is implicitly a subclass of owl:Thing; you need not say anything else. Then, if you create an instance myInstance and type it as a member of that OWL class, e.g., ex:myInstance rdf:type ex:UserDefinedClass . then myInstance is implicitly an instance of owl:Thing. This is true in any of the OWL dialects. --Frank ============================================= Since both seem OK to me, the question arises why this is possible at all. Why has the SW been made so complex? Time for a clean-up? Frank, if I would follow Ivan's advice, and typically use something explicit like: <owl:Thing rdf:ID="PHO-387392"/> <owl:Thing rdf:about="#PHO-387392"> <rdf:type rdf:resource="http://www.iso15926.org/part2/2003-12#PhysicalObject"/> <rdfs:label>Joe Blogg</rdfs:label> </owl:Thing> do you see any REAL disadvantage (other than the neglect of RDF)? Given the fact that we use OWL very rigorously by superimposing the ISO 15926-2 data model, clearly and consistently distinguishing individuals from classes by using owl:Thing seems to fit in that rigor (or rigour, if you want). We have to work with IDs like PHO-387392 anyway, since we deal with more than 20,000 classes and hundreds of thousands of individuals (all the things that make up an entire oil refinery, and the components thereof, and the process streams). We had a discussion about naming, and rejected human-understandable names. What would be the human-understandable name for a Ford Focus with a wide (not yet made) selection of engines, colors, accessories, etc? And what if that selection has been made? Regards, Hans PS We have to use OWL Full. OWL DL simply is too restricted. But given the fact that we have that superimposed data model in place, the reasoning isn't that complex, nor important. _______________________ Hans Teijgeler ISO 15926 specialist www.InfowebML.ws hans.teijgeler@quicknet.nl phone +31-72-509 2005
Received on Thursday, 27 October 2005 19:49:15 UTC