- From: Patrick Stickler <patrick.stickler@nokia.com>
- Date: Thu, 31 Jan 2002 10:57:13 +0200
- To: ext Brian McBride <bwm@hplb.hpl.hp.com>, RDF Core <w3c-rdfcore-wg@w3.org>
On 2002-01-30 21:41, "ext Brian McBride" <bwm@hplb.hpl.hp.com> wrote: > An updated summary of the datatyping issues, as I currently understand them. > > Issue B1: > ========= > In S, if one wants to use both idiom A and idiom B, e.g. > > <mary> <age> "10" . > <age> <rdfs:range> <xsd:integer.lex> . > > and > > <mary> <ageD> _:a . > _:a <xsd:integer.map> "10" . > > two properties have to be used, <age> and <ageD>, in this example. > I believe there is a agreement that this is a difference between the > two proposals. Indeed, it may be said that the main aim of TDL is > to avoid requiring different properties for these different idioms. > > Can't Live With: PatrickS I think it would be useful for the group to make explicit what the ramifications of this are -- which should make it clear (I hope) why I cannot live with it. In order to use both S-A and S-B in the same knowledge base, or syndicate knowledge using either idiom into a merged knowledge base, we would have to have *two* variants of every metadata vocabulary: DC, PRISM, ONIX, MARC, vCard, etc. I.e. dcA:title and dcB:title and then relate the two together so that queries asking for dc:title would obtain knowledge expressed in either idiom. Ouch. Yuck. Blech. Insert your favorite expletive here _____ ;-) I just can't see the RDF community at large buying into such a scenario. And it is imperative that we support both global and local typing for literals, so the alternative -- choose only S-A or S-B is equally unacceptable. > Issue B4 - TDL breaks existing code > =================================== > > This is similar to B3. I've changed the example slightly from Sergey's. > Under TDL, consider the graph: > > _:f <rdf:type> <film> . > _:f <dc:Title> (_, "10") . > <mary> <age> (_, "10"). > > Does this entail: > > _:x <dc:Title> ?y . > _:z <age> ?y . > > I believe there is agreement that it does not under the current TDL model > theory. No. This is not correct. We just don't seem to be connecting on this one Brian. It is an issue of whether the query is based on string equality or value equality -- whether datatyping is taken into consideration. If we treat the parenthesized versions as TDL pairings (which I think is your intent) and use that as an indication of whether the query is string or value based then I think the results should become clear. Let me try to expand it to all significant cases: -- Case 1: (value comparison, no datatyping specified) _:f <rdf:type> <film> . _:f <dc:Title> (_, "10") . <mary> <age> (_, "10"). DOES entail _:x <dc:Title> ?y . _:z <age> ?y . (though probably should flag some warnings since the query is expecting datatypes as that is the basis for value comparison) -- Case 2: (string comparison, datatyping ignored) _:f <rdf:type> <film> . _:f <dc:Title> "10" . <mary> <age> "10". DOES entail _:x <dc:Title> ?y . _:z <age> ?y . -- Case 3: (value comparison, datatyping defined) _:f <rdf:type> <film> . _:f <dc:Title> (xsd:string, "10") . <mary> <age> (xsd:integer, "10"). does NOT entail _:x <dc:Title> ?y . _:z <age> ?y . -- Case 4: (value comparison, datatyping partially defined) _:f <rdf:type> <film> . _:f <dc:Title> (_, "10") . <mary> <age> (xsd:integer, "10"). does NOT entail _:x <dc:Title> ?y . _:z <age> ?y . (and as with case 1 should probably flag a warning due to the unspecified typing) Is that clearer now? Cheers, Patrick -- Patrick Stickler Phone: +358 50 483 9453 Senior Research Scientist Fax: +358 7180 35409 Nokia Research Center Email: patrick.stickler@nokia.com
Received on Thursday, 31 January 2002 03:56:20 UTC