Re: datatypes without datatype maps

On Jun 12, 2013, at 12:28 PM, Peter Patel-Schneider wrote:

> I think that there is indeed something that is not correctly nailed down in
> Semantics.  Semantics says that datatype IRIs must identify datatypes, but
> it does not say that the datatype IRI must the denote the datatype that it
> identifies.  This should be added to definition of D-interpretations.

Yes. I have added this in the draft I am working on and also a biut more supporting prose in the introductory paragraph.

Pat


> 
> If that is the problem with D-interprtations that Antoine refers to, then I
> think that the change above addresses his comment.  However, if Antoine is
> commenting more generally about the change away from datatype maps, here is
> my description of the changes between the 2004 semantics and the semantics
> in the current editors' draft.
> 
> 
> 
> In the 2004 Semantics the semantics of datatypes are given via datatype
> maps, which contain pairs consisting of a URI and a datatype which is, in
> turn, a triple consisting of the lexical space, the value space, and the L2V
> mapping.
> 
> In the current editor's draft of RDF 1.1 Semantics the semantics of
> datatypes are given via a set of IRIs that must each identify a datatype.
> With my change above in a D-interpretation a datatype IRI must denote its
> datatype.  (Without the change a datatype IRI must denote something with an
> L2V mapping and a value space.)
> 
> 
> It may appear that something is lost here.  Given a only set of IRIs
> identifying datatypes, where are the actual datatypes?  There are two
> answers here:
> 
> 1/ Before you can say that the IRIs identify datatypes you have to have a
> datatype in question, so everything works out correctly.
> 
> 2/ It doesn't really matter.  The actual workings of a datatype are external
> to the formal machinery of RDF, so there is necessarily some magic so there
> is no way to be as precise as is really required.  This is true even for the
> 2004 version.  Although there is the formal statement of a dataype map,
> there is no formal RDF machinery for specifying the internal workings of a
> dataype.  Instead one would say that a datatype map contains xsd:integer and
> maps xsd:integer to the XSD integer datatype.  The only change is that there
> now is no formal datatype map, so that one can't say that D is a datatype
> map and just use D thereafter in a document.  Instead one says that D is a
> set of datatype IRIs and that they identify particular datatypes and just
> use D thereafter in a document.
> 
> 
> So suppose that I want to create a particular system that handles four
> datatypes - HTML literals as defined in RDF concepts, integers as defined by
> XSD, real numbers as defined by the OWL WG, and complex numbers as defined
> by me.
> 
> Under the 2004 way I would proceed by creating a datatype map,
> F = {<rdf:HTML,A>,<xsd:integer,B>,<owl:real,C>,<pfps:complex,D>},
> where A is the HTML datatype as defined in RDF 1.1 Concepts at
> http://www.w3.org/TR/owl2-syntax/#Real_Numbers.2C_Decimal_Numbers.2C_and_Integers,
> B is the integer datatype as defined in XS Datatypes
> at http://www.w3.org/TR/xmlschema11-2/#integer,
> C is the real datatype as defined in OWL 2 at
> http://www.w3.org/TR/owl2-syntax/#Real_Numbers.2C_Decimal_Numbers.2C_and_Integers,
> D is the datatype whose value space is pairs of real numbers ....
> Thereafter I just F, perhaps also pointing back where F is specified.
> 
> Under the current way I would proceed by saying that
> F = {rdf:HTML,xsd:integer,owl:real,pfps:complex}
> where rdf:HTML identifies the HTML datatype as defined in RDF 1.1 Concepts at
> http://www.w3.org/TR/owl2-syntax/#Real_Numbers.2C_Decimal_Numbers.2C_and_Integers,
> xsd:integer identifies the integer datatype as defined in XS Datatypes at
> http://www.w3.org/TR/xmlschema11-2/#integer,
> owl:real identifies the real datatype as defined in OWL 2 at
> http://www.w3.org/TR/owl2-syntax/#Real_Numbers.2C_Decimal_Numbers.2C_and_Integers,
> pfps:complex identifies the datatype whose value space is pairs of real
> numbers ....
> Thereafter I just use F, perhaps also pointing back to F is specified.
> 
> Actually, under the current way I don't need to say what the interpretation
> of rdf:HTML or xsd:integer is because these interpretation are fixed by RDF
> 1.1 Concepts.
> 
> peter
> 
> 

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Received on Saturday, 15 June 2013 19:03:19 UTC