- From: Graham Klyne <Graham.Klyne@MIMEsweeper.com>
- Date: Thu, 07 Feb 2002 17:42:57 +0000
- To: Pat Hayes <phayes@ai.uwf.edu>
- Cc: Sergey Melnik <melnik@db.stanford.edu>, w3c-rdfcore-wg@w3.org
I finally figured out why 'dtype' is needed, but a corresponding extensions to 'range' is (maybe) not. 'type' inferences are intimately bound to subclassing, so the addition of subclassing assertions that are quite reasonable with respect to the value domains could completely mess up the datatyping. (I'm sure you explained this Pat, but somehow I wasn't hearing.) This did make me wonder is there might not be a similar problem with respect to 'range' and 'subPropertyOf': if aaa range ddd (ddd some datatype) and bbb range ccc (ccc some class) then these statements don't say anything about literal interpretation for ccc, even if ccc subClassOf ddd But adding: bbb subproperty aaa also adds an inference bbb range ddd which in turn invokes the dtype relation for subjects of bbb. Just a thought. #g -- At 10:50 AM 2/7/02 -0600, Pat Hayes wrote: >>Alternatively, why not just pretend there is a 'rule' >> >> xxx rdf:type ddd . >> xxx rdf:value vvv . >> ---> >> xxx ddd vvv . > >Well, use rdf:dtype rather than rdf:type, but yes; in fact this inference >is valid in the proposed MT extension in any case. But this doesnt do >range-datatyping by itself, as there is no RDFS inference path from >rdfs:range to rdf:dtype. I think its too dangerous to make people use >rdf:type, in general. It would be very tricky to be sure that some piece >of RDFS closure reasoning didn't accidentally make an unintended or >inconsistent datatype class association. The rdfs closure rules can have >very 'remote' consequences, involving things like subclasses of ranges of >subproperties. ------------------------------------------------------------ Graham Klyne MIMEsweeper Group Strategic Research <http://www.mimesweeper.com> <Graham.Klyne@MIMEsweeper.com>
Received on Thursday, 7 February 2002 12:49:49 UTC