- From: Jan Grant <Jan.Grant@bristol.ac.uk>
- Date: Tue, 25 Jun 2002 16:36:30 +0100 (BST)
- To: pat hayes <phayes@ai.uwf.edu>
- cc: w3c-rdfcore-wg@w3.org
On Tue, 25 Jun 2002, pat hayes wrote: > >On Tue, 25 Jun 2002, pat hayes wrote: > > > >> > >> >in two parts. > >> > > >> >One, for symmettry, where a literal "really is" a string, > >> > >> Well, that question is now moot, since a literal is *never* a string. > >> A literal is a 3-tuple. Thus: > >> > >> >do we have an > >> >analagous situation to the Cannes entailment? > >> > > >> > eg:book dc:title "the big book of RDF" . > >> > > >> >entails... > >> > > >> > eg:book dc:title _:a . > >> > _:a xsd:string "the big book of RDF" . > >> > >> No, that cannot possibly be valid. The thing inside those quotes is > >> either not a string or not a literal. Im not yet quite sure which is > >> correct: maybe its neither of them. > > > >Hang on, you've spotted the get-out (that the thing in quotes is a > >Literal, but not an xsd:string), but given that I fail to see why the > >above entailment should not hold. > > Because the value of dc:title can always be chosen to not be an > xsd:string and still satisfy the first triple. Those interpretations > will block the entailment. > > >Unless the datatyping proposal gives a > >uniform treatment to _all_ xsd datatypes, I can't see how we can vote in > >favour of it. > > Well, I agree. If the literals in the graph really are 3-tuples, then > ALL of the datatyping debate - all of which was under the false > assumption that literals were items in datatype lexical spaces, ie > strings - has been rendered moot. We simply don't have datatyping in > RDF graphs, with these literals: it's meaningless. The 3-tuple > <1,"10","french"> isn't in the lexical space of any XSL datatype. Urk! I had read the datatyping proposal with the notion that jenny eg:age _:a . _:a xsd:int "10" . used some f:Literal->XSD lexical space such that f(<1, "10", null>) = "10" - ie, that trivial, unlanguage-tagged, unxmlised literals were being used for their mapping to the XSD datatype lexical space. Apologies for terminological confusion in that last sentence. > >If we have to accept non-regularity in datatyping then > >there are far simpler approaches that support the xsd types "natively" > >and other types using a daml-like construct that seem much more natural. > > I'd like to know the details of them. We have considered the daml > ideas before, at length, and they were resoundingly rejected by the > WG. This is an aside, so I'll follow up with it separately. -- jan grant, ILRT, University of Bristol. http://www.ilrt.bris.ac.uk/ Tel +44(0)117 9287088 Fax +44 (0)117 9287112 RFC822 jan.grant@bris.ac.uk I am now available for general use under a modified BSD licence.
Received on Tuesday, 25 June 2002 11:39:36 UTC