- From: pat hayes <phayes@ihmc.us>
- Date: Tue, 8 Jul 2003 08:57:18 -0500
- To: <Patrick.Stickler@nokia.com>, "Peter F. Patel-Schneider" <pfps@research.bell-labs.com>
- Cc: <www-rdf-comments@w3.org>
> > -----Original Message----- >> From: ext pat hayes [mailto:phayes@ihmc.us] >> Sent: 08 July, 2003 05:40 >> To: Peter F. Patel-Schneider >> Cc: www-rdf-comments@w3.org >> Subject: Re: possible peculiarity with empty datatypes >> >> >> >> >Hi: >> > >> >A datatype, d, with an empty value space may end up in an >> unusual state >> >because it has no instances, and thus would not trigger any >> > x rdf:type d >> >semantic conditions (assuming that such semantic conditions >> are included in >> >RDFS). >> >> My own sense is that there should be no such datatype. I will add >> this to the required conditions for a datatype, ie that the value >> space is nonempty. > >Perhaps better to specify that the lexical space is non-empty, >which is an equally reasonable constraint, I think, and then >it will follow from the definition of L2V that the value space >is thus nonempty. To be safe Ive added both conditions. I now realize that the datatype entailment rules already assumed this, in fact (otherwise rdfD1 might not be valid) and Ive added an Lbase axiom-let to capture it: a datatype property is now required to not be universally false. Pat -- --------------------------------------------------------------------- IHMC (850)434 8903 or (650)494 3973 home 40 South Alcaniz St. (850)202 4416 office Pensacola (850)202 4440 fax FL 32501 (850)291 0667 cell phayes@ihmc.us http://www.ihmc.us/users/phayes
Received on Tuesday, 8 July 2003 09:57:19 UTC