- From: Pat Hayes <phayes@ai.uwf.edu>
- Date: Wed, 17 Apr 2002 16:14:56 -0500
- To: Patrick Stickler <patrick.stickler@nokia.com>
- Cc: 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 is meaningless or false, Im not sure which. There is no notion of 'context' in RDF, and the interpretation in fact says that the value of the property is a string, not an 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 MT does not refer to contexts or pairings, and it does not say that the in-line idiom refers to datatype values. > >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). Right. Notice that is ALL it says in this case. It doesn't mention the datatype value. >-- > >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. Im not sure what 'the value indicated' means, but this certainly does NOT say that Jenny's age is ten. It says that the ex:age of Jenny is the string "10". It doesn't say anything about the datatype value. >I.e. the datatype-specific interpretation of the above >RDF knowledge is that Jenny's age is ten. WRONG. It is the string "10", with or without datatyping. All that the datatyping adds to this is check on the lexical form, which would rule out for example Judy <ex:age> "boodle" . as ill-typed. To conclude that Jenny's ex:age is ten would be a mistake, an invalid inference. We should make this painfully clear to users, so they do not get their RDF in a muddle. >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, Yes, exactly. That is all it asserts in this case, and it is very important that it does not assert more, or else the DCore-style applications will break. > but >given the definition of datatypes, everything else follows >automatically ?? What 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 No, the MT *specifies* which value is indicated. That is what the MT is for. And in this case, the value of the property is a string. >-- 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 Yes, in a sense. Id rather say that the statement arises from a particular kind of association, as specified in the RDF graph syntax, since different 'associations' have different meanings. >-- is to define a datatyped literal pairing. No. Pairings aren't in the syntax and aren't mentioned in the MT. > > L2V(I(xsd:integer))("10") is a datatyped literal pairing. No, it isn't. In fact, it is a datatype value, viz the number ten (obtained by applying the lexical-to-value map L2V(I(xsd:integer)) to the argument "10"; the former itself being obtained by applying the global L2V mapping to the datatype I(xsd:integer) denoted by the uriref.) > Datatyped literal pairings thus have definition in the MT. > >let me repeat that in case some of you missed it ;-) I didn't miss it, but its wrong. There are no pairings in the MT. In fact there are no expressions anywhere in the document I wrote that can possibly be interpreted as referring to such pairings. 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 Wednesday, 17 April 2002 17:14:59 UTC