- From: Pat Hayes <phayes@ai.uwf.edu>
- Date: Wed, 27 Feb 2002 17:05:27 -0600
- To: w3c-rdfcore-wg@w3.org
Guys, I started drafting a new version of the MT to reflect our staked-down decision that literals always denote themselves. This simplifies (and clarifies) the graph syntax and the basic MT, but it could be done in several different ways, so I wonder if anyone has any strong views on any of the following question: should we allow literals to entail bnodes ? At present, a graph entails its existential generalization which is gotten by 'erasing' urirefs into bnodes, eg ex:Jenny ex:age what:ever . |= ex:Jenny ex:age _:x . Do we want this to be true for literals as well? Eg should this be a valid inference? ex:Judy ex:age "10" . |= ex:Judy ex:age _:x . It seems to me that we should do this, since there is no doubt that literals do denote something - themselves, in fact - in any interpretation. This means that the following inference would be valid, for example: ex:Jenny ex:age "10" . |= ex:Jenny ex:age _:y . which might seem a bit worrying if there was an rdfs:drange assertion around, eg ex:age rdfs:drange xsd:number which imposes the 'lexical' datatype in the first case, but looks like it might impose the 'value' in the second case; but in fact it is OK, since that conclusion would only trigger the value datatyping constraint if the bnode were also the subject of rdfs:dlex; and that in turn would require the original graph to have had something like this in it: ex:Jenny ex:age "10" . "10" rdfs:dlex "12" . which is so crazy that no-one should be surprised if it has crazy entailments, right? Anyway, if y'all agree that we should accept this inference, then I think the simplest way to re-do the MT is to simply say up-front that *all* RDF interpretations must include *all* literals in their universe. Then we can just say that for literals E, I(E) = E, and not talk about things like LV and XL at all. Does anyone have any philosophical objections to this? It would allow quite a few of the lemmas to be stated with fewer qualifications, and the proofs to be simplified. 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
Received on Thursday, 28 February 2002 11:53:53 UTC