- From: <jos.deroo.jd@belgium.agfa.com>
- Date: Fri, 27 Jul 2001 15:55:54 +0100
- To: phayes@ai.uwf.edu
- Cc: bwm@hplb.hpl.hp.com, w3c-rdfcore-wg@w3.org
[still not recovered from a very deep impression] [...] > 5. Skolemisation > > If we replace an anonNode by a uriref, the result is not entailed by the original > document. In fact, in general, if E' contains any urirefs not contained in E then > E cannot entail E'. For example, the document containing the single triple > <foo> <baz> _:xxx > obviously bears some relation to the triple > <foo> <baz> <bar> > but it does not entail it, since the interpretation > {1,2}/1->{<1,1>}/{foo->1,baz->1,bar->2} > satisfies the first document but not the second. (Notice this interpretation > assigns a value to something - <bar> - outside the vocabulary of the first > document, which is how the entailment fails.) > > However, the second triple entails the first document, since any interpretation > which satisfies <foo> <bar> <baz> can be used to make the first document true by > restricting it to the smaller vocabulary and assigning the interpretation of > <bar> to the anonNode to provide a suitable I[A] mapping. i guess this is called "existential introduction", no? > More significantly, any RDF expression which is entailed by the second triple > and does not contain <bar> is also entailed by the first document. why is that significant? [...] -- Jos De Roo, AGFA http://www.agfa.com/w3c/jdroo/
Received on Friday, 27 July 2001 09:58:06 UTC