- From: pat hayes <phayes@ai.uwf.edu>
- Date: Tue, 3 Dec 2002 13:46:23 -0600
- To: fmanola@mitre.org
- Cc: w3c-rdfcore-wg@w3.org
>pat hayes wrote: >> >> > >> >General comment, not specifically Primer: the description of >> >rdf:value is fine, but how does it relate to a normative >> >specification? What can we say formally about rdf:value? >> >> Right now, we say explicitly that it has no particular meaning. >> >> >What formal semantics (interpretation) allows us to make inferences like: >> > >> > my:cat rdf:type ex:DomesticCat . >> > my:cat ex:weight _:x . >> > _:x rdf:value "15" . >> > _:x ex:unit ex:Kilogram >> > >> >=> >> > >> > my:cat rdf:type ex:Obese . >> >> Nothing in the MT provides any connection in meaning between the >> third and fourth triple of the first graph. > >I assume you mean beside the fact that they both have the same subject? Well, yes. I mean, there isn't any formal support for that (or any other) entailment involving rdf:value >Anyway, this isn't specific to rdf:value is it? Well, it seems to me that rdf:value is being used in a way that kind of expects a semantics that it currently does not have. SO maybe we should give it one. >I mean, you couldn't >make the inference if you'd used a datatype "weightInKilograms" either. >You'd need much more machinery than RDF has. The point wasnt to do with the particular datatype, but the use of rdf:value. Right now rdf:value might as well not be there as far as the MT is concerned, it has no meaning at all. You could get the same effect by writing ex:foo instead. > >> >> I was under the impression that we had formally decided NOT to >> support this kind of usage. Wasn't that part of the local-datatyping >> no-fancy-idioms decision? >> >> >but NOT: >> > >> > my:cat rdf:type ex:DomesticCat . >> > my:cat ex:weight _:x . >> > _:x rdf:value "15" . >> > _:x ex:unit ex:Pound >> > >> >=> >> > >> > my:cat rdf:type ex:Obese . >> > >> >? >> > >> >My point here is if we are to encourage such usage of rdf:value, >> >then there ought to be some normative description to back up such >> >usage. >> >> I agree. Either we should not mention this stuff, or else we should >> back it up with some semantics. > >Well, that doesn't seem to be the principle on which we've been >operating! If we're going to deal with this, let's do rdfs:isDefinedBy >too! I would if I thought it had any meaning. The trouble with that one is that 'is defined by' really, really is meaningless when applied to pieces of RDF. RDF *never* defines anything, it can't possibly define anything since it doesn't have negation. So forget about rdfs:isDefinedBy, OK? > >> It wouldn't be hard to do and it >> would also enable us to do some neat datatyping entailments that >> people seem to think are obvious, such as (with appropriate >> wellformedness caveats) >> >> aaa ppp "sss"^^ddd . >> >> --> >> >> aaa ppp _:x . >> _:x rdf:value "sss" . >> _:x rdf:type ddd . >> > >Yes, keeping in mind that rdf:value can be used with more complicated >relationships too (i.e., _:x could have multiple properties qualifying >the value, not just a single one). Right, that's the limitation, but we can get that from the MT as well. So more generally, to the WG: should I give rdf:value a model theory? Speak soon, guys. Unless I hear otherwise I will do this: aaa rdf:value "bbb" . means that there is some conventional mapping M from lexical forms under which I(aaa) = M(bbb). Doesn't say much, but it might be useful, particularly if we say that any datatype L2V mapping counts as a 'conventional mapping'. Pat > >--Frank > >-- >Frank Manola The MITRE Corporation >202 Burlington Road, MS A345 Bedford, MA 01730-1420 >mailto:fmanola@mitre.org voice: 781-271-8147 FAX: 781-271-8752 -- --------------------------------------------------------------------- IHMC (850)434 8903 home 40 South Alcaniz St. (850)202 4416 office Pensacola (850)202 4440 fax FL 32501 (850)291 0667 cell phayes@ai.uwf.edu http://www.coginst.uwf.edu/~phayes s.pam@ai.uwf.edu for spam
Received on Tuesday, 3 December 2002 14:46:05 UTC