- From: Graham Klyne <Graham.Klyne@MIMEsweeper.com>
- Date: Thu, 07 Feb 2002 10:08:06 +0000
- To: Pat Hayes <phayes@ai.uwf.edu>
- Cc: w3c-rdfcore-wg@w3.org
At 05:25 PM 2/6/02 -0600, Pat Hayes wrote: >>At 12:25 PM 2/6/02 -0600, Pat Hayes wrote: >>>>I see two ways of how the semantics of reification could be attacked: >>>> >>>>1. Explain the semantics using bNode + 4-triple constructs. Applications >>>>are free to use a compact representation. If statements are used as >>>>first-class objects, they can be treated just as some kind of bNodes. >>>>The API-level identity of such bNodes is functionally determined by >>>>their (s,p,o)-description. Alternatively, the applications can generate >>>>exactly one such bNode for each (s,p,o) etc. Same trick could be applied >>>>for dealing with functionally determined bNodes in the model theory. >>> >>>No trick is needed. The ordinary MT already would treat the 4-triples in >>>this way already; reification is semantically transparent, on this view. >>>Which is another way of saying that we are trashing it. After all, >>>there's no way to stop anyone writing those 4-triples if they want to, >>>right? Trashing it doesn't make it illegal, it just says that we aren't >>>saying anything particular about what it means: its not a language >>>feature, its just a way you might want to write some RDF. Go ahead if >>>y'all feel like it. >> >>I want to pick up on two points here: >> >>(1) there is provision (in RDFM&S) for a reified statement to be >>identified (e.g. by rdf:ID='xxx' on the corresponding property element), >>so simply saying reified statements are treated as bNodes seems to miss >>something. > >Ah, that is exactly what I wanted to focus on. WHAT DOES THAT MEAN ?? To >'identify' a reified statement, that is. Is the identifying ID a URI? If >so, then why doesnt the 4-triple use that URI instead of a bnode? If not, >what can 'identify' possibly mean in RDF? Well, by my reading of current M&S, I think is does; i.e. <rdf:Description rdf:about='ex:subj'> <ex:prop rdf:id='ex:reif' rdf:resource='ex:obj'/> </rdf:Description> yields: <ex:reif> <rdf:type> <rdf:Statement> . <ex:reif> <rdf:subject> <ex:subj> . <ex:reif> <rdf:predicate> <ex:prop> . <ex:reif> <rdf:object> <ex:obj> . which was my point: I didn't think the statement resource was necessarily a bnode. (Of course, this entails the bnode case, right?) #g -- >>(2) accepting almost all of the above that the reification properties are >>mostly like any other RDF properties, we need to express a view on this >>entailment: >> >> <ex:subj> <ex:prop> <ex:obj> . >>entails >> _:r <rdf:type> <rdf:Statement> . >> _:r <rdf:subject> <ex:subj> . >> _:r <rdf:predicate> <ex:prop> . >> _:r <rdf:object> <ex:obj> . >>? >> >>What you say above suggests no such entailment. > >Right. > >Pat > >-- >--------------------------------------------------------------------- >IHMC (850)434 8903 home >40 South Alcaniz St. (850)202 4416 office >Pensacola, FL 32501 (850)202 4440 fax >phayes@ai.uwf.edu http://www.coginst.uwf.edu/~phayes ------------------------------------------------------------ Graham Klyne MIMEsweeper Group Strategic Research <http://www.mimesweeper.com> <Graham.Klyne@MIMEsweeper.com>
Received on Thursday, 7 February 2002 05:46:35 UTC