- From: Patrick Stickler <patrick.stickler@nokia.com>
- Date: Wed, 17 Apr 2002 11:51:16 +0300
- To: ext Graham Klyne <Graham.Klyne@mimesweeper.com>
- CC: Pat Hayes <phayes@ai.uwf.edu>, RDF Core <w3c-rdfcore-wg@w3.org>
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. 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
Received on Wednesday, 17 April 2002 04:48:26 UTC