- From: Dan Connolly <connolly@w3.org>
- Date: Wed, 13 Dec 2000 09:11:48 -0600
- To: jos.deroo.jd@belgium.agfa.com
- Cc: " - *Ora.Lassila@nokia.com" <Ora.Lassila@nokia.com>, " - *www-rdf-logic@w3.org" <www-rdf-logic@w3.org>
jos.deroo.jd@belgium.agfa.com wrote: > > Ora wrote in a reply to Pat: > > > Ah, I discern a ray of hope. Am I correct, then, in thinking > > > that by asserting a reified description of a triple (that is, > > > the four triples which describe it as being a triple plus > > > giving its three components), one is NOT thereby also > > > asserting the triple itself? That would greatly simplify the > > > semantics of RDF, certainly. > > Exactly! Asserting the reification is independent from asserting > > the triple itself. And only those statements we have asserted > > we consider as "facts". > > Ok, maybe we are completely wrong (please tell us), but we see a > distinction between asserting > <rdf:Statement> > <rdf:subject>#cernDoc</rdf:subject> > <rdf:predicate>#includes</rdf:predicate> > <rdf:object>thisDocument</rdf:object> > </rdf:Statement> > > and asserting > <rdf:Description> > <rdf:type resource="http://www.w3.org/1999/02/22-rdf-syntax-ns#Statement"/> > <rdf:subject resource="#cernDoc"/> > <rdf:predicate resource="#includes"/> > <rdf:object>thisDocument</rdf:object> > </rdf:Description> > > In the first ("assembly" RDF) representation the single statement > [#cernDoc] #include [thisDocument] > is asserted and becomes a fact Huh? No, it represents the 4 statements: [#genid] rdf:type [rdf:Statement] [#genid] rdf:subject "#cernDoc" [#genid] rdf:predicate "#includes" [#genid] rdf:object "thisDocument" The only difference between the two is that "#cernDoc" and "#includes" are strings in the first case, and symbols (URI references) in the second case. > > In the second (reified RDF) representation the 4 statements > [#genid] rdf:type [rdf:Statement] > [#genid] rdf:subject [#cernDoc] > [#genid] rdf:predicate [#includes] > [#genid] rdf:object [thisDocument] > are asserted as 4 facts and indeed nothing is asserted about > the triple itself! Nope, they both give 4 statements-about-a-statement. > > I know that the first representation is very confusing and > lengthy and not human readable and so on, but it is (I think) > valid RDF and it is a way to have "compound" subjects and objects > such as in http://www.agfa.com/w3c/euler/lists.axiom.rdf > without the need for reification. > Only the "outer" statements are asserted (as facts, Horn clauses, > etc) so a "nested" statement is not asserted at all. > > -- > Jos De Roo, AGFA -- Dan Connolly, W3C http://www.w3.org/People/Connolly/
Received on Wednesday, 13 December 2000 10:26:32 UTC