Re: How does RDF get extended to new datatypes?

It seems to me that this problem is due to the removal of the notion of 
datatype map. In 2004, applications could implement the D-entailment 
they liked, with D being a partial mapping from IRI to datatypes.
Now, there are just IRIs in D. The association between the IRI and the 
datatype it should denote is completely unspecified. The only indication 
that the application can have to implement a datatype map is that XSD 
URIs must denote the corresponding XSD datatypes.

I have troubles understanding why datatype maps should be removed. I 
don't remember any discussions saying that they should be changed to a 
set. This change, which now creates issues, suddenly appear in RDF 
Semantics ED, with no apparent indication that it was motivated by 
complaints about the 2004 design.

Currently, I see a downside of having a plain set, as it does not 
specify to what datatype the IRIs correspond to, while I do not see the 
positive side of having a plain set. Can someone provide references to 
evidence that this change is required or has more advantages than it has 
drawbacks?


AZ.

Le 24/04/2013 05:09, Pat Hayes a écrit :
> I think we still have a datatype issue that needs a little thought.
>
> The D in D-entailment is a parameter. Although RDF is usually treated
> as having its own special datatypes and the compatible XSD types as
> being the standard D, it is quite possible to use RDF with a larger D
> set, so that as new datatypes come along (eg geolocation datatypes,
> or time-interval datatypes, or physical unit datatypes, to mention
> three that I know have been suggested) and, presumably, get canonized
> by appropriate standards bodies (maybe not the W3C, though) for use
> by various communities, they can be smoothly incorporated into RDF
> data without a lot of fuss and without re-writing the RDF specs.
>
> Do we want to impose any conditions on this process? How can a reader
> of some RDF know which datatypes are being recognized by this RDF?
> What do we say about how to interpret a literal whose datatype IRI
> you don't recognize? Should it be OK to throw an error at that point,
> or should it *not* be OK to do that? Shouid we require that RDF
> extensions with larger D's only recognize IRIs that have been
> standardly specified in some way? How would we say this?
>
> The current semantic story is that a literal
> "foo"^^unknown:datatypeIRI  is (1) syntactically OK (2) not an error
> but (3) has no special meaning and is treated just like an unknown
> IRI, ie it presumably denotes something, but we don't know what. Is
> this good enough?
>
> Pat
>
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Received on Wednesday, 24 April 2013 14:07:17 UTC