- From: Graham Klyne <Graham.Klyne@MIMEsweeper.com>
- Date: Thu, 14 Feb 2002 17:21:19 +0000
- To: Dan Connolly <connolly@w3.org>
- Cc: w3c-rdfcore-wg@w3.org
At 04:18 PM 2/13/02 -0600, Dan Connolly wrote: >I really wrestle with this. The M&S spec is quite clear that >the answer is YES, as PeterPS has pointed out in >his message to www-rdf-logic of 04 Feb 2002 13:24:08 -0500. I read PeterPS' message on RDF-logic, and was not convinced by it that RDF M&S is clear about this issue: [[[ If you read the RDF M&S there are quite clear statements of the status of reified statements. A statement and its corresponding reified statement exist independently in an RDF graph and either may be present without the other. [RDF M&S, 4.1] This sentence does not admit multiple reified statements for a single statement. RDF M&S is also quite clear that only one statement can exist with the same subject, predicate, and object. There is a set called Statements, each element of which is a triple of the form {pred, sub, obj} [RDF M&S, 5] Just afterward there is more wording that indicates that a statement can only have one reification ... we can express the reification of this as a new resource ... [RDF M&S, 5] So, for any triple there is at most one statement, and for every statement there is at most one reification. ]]] 1. I agree that M&S allows only one statement with given sub, pred, obj. 2. M&S may not specifically admit more than one reification of a statement, but it also does not (to me) clearly deny the possibility. 3. The sentence containing "express the reification" would suggest only one reification, but that's a lot of consequence to hang on one use of a definite article (as opposed to an indefinite article). So, while the spec *can* be read as indicating only one reification per statement, I would disagree that it is clear about this. I wouldn't design software around that assumption on the basis of what I read in M&S. #g -- >On Wed, 2002-02-13 at 16:18, Frank Manola wrote: >[...] > > 1. Brian suggests that we (explicitly) decide on answering the > > question: Does > > > > <stmt1> <rdf:type> <rdf:Statement> . > > <stmt1> <rdf:subject> <subject> . > > <stmt1> <rdf:predicate> <predicate> . > > <stmt1> <rdf:object> <object> . > > > > <stmt2> <rdf:type> <rdf:Statement> . > > <stmt2> <rdf:subject> <subject> . > > <stmt2> <rdf:predicate> <predicate> . > > <stmt2> <rdf:object> <object> . > > > > <stmt1> <property> <foo> . > > > > entail: > > > > <stmt2> <property> <foo> . > > > > [Brian suggests that the answer is NO] > >I really wrestle with this. The M&S spec is quite clear that >the answer is YES, as PeterPS has pointed out in >his message to www-rdf-logic of 04 Feb 2002 13:24:08 -0500. ------------------------------------------------------------ Graham Klyne MIMEsweeper Group Strategic Research <http://www.mimesweeper.com> <Graham.Klyne@MIMEsweeper.com>
Received on Thursday, 14 February 2002 12:56:28 UTC