- From: Graham Klyne <Graham.Klyne@MIMEsweeper.com>
- Date: Wed, 17 Apr 2002 10:27:23 +0100
- To: Patrick Stickler <patrick.stickler@nokia.com>
- Cc: Pat Hayes <phayes@ai.uwf.edu>, RDF Core <w3c-rdfcore-wg@w3.org>
At 11:51 AM 4/17/02 +0300, Patrick Stickler wrote: >On 2002-04-16 23:24, "ext Graham Klyne" <Graham.Klyne@MIMEsweeper.com> >wrote: > > > At 08:09 PM 4/16/02 +0300, Patrick Stickler wrote: > > > >>> Jenny age "10" . > >>> age rdfd:range xsd:integer . > > > >> ... the combination of the > >> inline idiom and the rdfd:range/datatype assertion designates > >> the pairing <xsd:integer, "10"> and that pairing is the basis > >> for any datatyping interpretation. I.e., the knowledge in the > >> graph unambiguously identifies a single value by designating > >> a datatyped literal pairing. What that actual > >> value is, we don't know *at this level*. But at a higher level > >> where the full knowledge of xsd:integer is available, then > >> we know that the pairing <xsd:integer, "10"> identifies the > >> value ten. > >> > >> The RDF Datatyping MT is not saying the value is ten. It is > >> saying that it is whatever value is identified by the interpretation > >> of the lexical form "10" within the context of the datatype > >> xsd:integer. > >> > >> That may seem like a very slight distinction, but it is > >> a very significant one. > > > > Slight, maybe. Significant, definitely, in the sense that (as far as I can > > tell) it goes beyond that which is specified by the model theory. > >No, it does not go beyond the MT. It is exactly what the MT states. > >The present datatyping MT says for this particular example: > >-- > >(3) ... if E contains the triples > > <ex:age, rdfd:datatype, xsd:integer> > <Jenny, ex:age, "10"> > >then L2V(I(xsd:integer))("10") is defined; >i.e. "10" is in the lexical space of I(xsd:integer). > >-- > >Thus the literal "10" is a member of the lexical space >of xsd:integer, and there is only one member of the value space of >xsd:integer represented by "10", therefore according to the >datatype xsd:integer, the value indicated by the above statements >is ten. > >I.e. the datatype-specific interpretation of the above >RDF knowledge is that Jenny's age is ten. Granted, the value >ten has no denotation in the graph, but it is unambiguously >identified by the idiom, in the context of the full semantics >of xsd:integer. OK, lets revert to a test case: foo rdfd:range xsd:integer . foo rdfd:range xsd:string . Jenny foo "10" . I believe this is completely valid according to Pat's last datatype spec [1], but how am I to decide which rdfd:range applies in determining the intended value of Jenny's 'foo'? As far as I can tell, the rest of your message deals with additional inferences that you might care to draw, but which are not sanctioned by the model theory. I searched the text of Pat's proposal [1] (our stake in the ground), and found no occurrence of the word "pair" or "pairing". #g -- [1] http://www.coginst.uwf.edu/users/phayes/simpledatatype23-02-2002.html [[[ Similarly, if two different rdfs:drange assertions are made about the same property, then they both apply to it. If the relevant datatypes have disjoint lexical spaces, or if their lexical-to-value maps fail to give the same values to a lexical form, then any use of the property with a literal is likely to produce a datatype clash. This requires particular care when merging information from different graphs which may have been written with different, and incompatible, conventions about literal datatyping. ]]] >Now, some folks seem to assert that all the datatyping MT asserts >is that "10" is a valid lexical form for xsd:integer, but >given the definition of datatypes, everything else follows >automatically so I don't see the real distinction. > >It is true that at the RDF MT level, it is not possible to >know which value is indicated -- but it is possible to >know that a single specific value is indicated, and know >that it is the value represented by the particular lexical >form according to the semantics of a particular datatype. > >To state that a given literal is a member of the lexical >space of a particular datatype is to associate that literal >with the datatype -- is to define a datatyped literal pairing. > > L2V(I(xsd:integer))("10") is a datatyped literal pairing. > Datatyped literal pairings thus have definition in the MT. > >let me repeat that in case some of you missed it ;-) > > L2V(I(xsd:integer))("10") is a datatyped literal pairing. > Datatyped literal pairings thus have definition in the MT. > >Thus, what the RDF MT provides is a datatyped literal pairing >which may be evaluated at a level above RDF by an application >with the full knowledge of the datatype in question in order >to obtain the actual value. > >Patrick > >-- > >Patrick Stickler Phone: +358 50 483 9453 >Senior Research Scientist Fax: +358 7180 35409 >Nokia Research Center Email: patrick.stickler@nokia.com ------------------- Graham Klyne <GK@NineByNine.org>
Received on Wednesday, 17 April 2002 05:22:01 UTC