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Re: Question about datatype maps

From: Alan Ruttenberg <alanruttenberg@gmail.com>
Date: Fri, 12 Sep 2008 11:12:51 -0400
Message-ID: <29af5e2d0809120812m6fbf77f0o4e9384cc63c96b2d@mail.gmail.com>
To: "Michael Schneider" <schneid@fzi.de>
Cc: "W3C OWL Working Group" <public-owl-wg@w3.org>

On Fri, Sep 12, 2008 at 7:02 AM, Michael Schneider <schneid@fzi.de> wrote:
> Hi Alan!
>
> Alan Ruttenberg wrote:
>
>>The OWL specification has a datatype map as a parameter. It's unclear
>>to me what are allowable extensions in the realm of datatypes, and
>>whether such extensions would be desirable from an interoperability
>>point of view. Now that we have a wide range of datatypes, do we need
>>to support extensibility here? Our experience OWL 1, OWL 2, that
>>choice and semantics of datatypes are not a slam-dunk obvious choice,
>>raising questions about whether sanctioned extensions to OWL in this
>>dimension would be beneficial or cause more trouble than they are
>>worth. Of course nothing would prevent unsanctioned extensions - my
>>question here is of what we should encourage.
>>
>>-Alan
>
> I simply would not say anything. Of course, we cannot forbid that
> implementers support additional datatypes. And custom datatypes, such as
> complex numbers, will make sense and add value in certain domains. Interop
> is then given by the OWL 2 spec: As long as an ontology only uses those
> datatypes, which are defined in the OWL 2 spec, no problems will arise with
> reasoners that /at least/ support all these OWL 2 datatypes [1]. If,
> however, an ontology uses additional datatypes, all bets are off; but why
> should we care as a WG? That's then in the responsibility of those who
> create and use such ontologies (they have to settle on a certain reasoner,
> etc.).

Well, this is kind of my point. We are currently saying *something*.
Why mention the concept of datatype map at all, instead of just
documenting the datatypes? Currently datatype maps are mentioned in
virtually all the documents. Wouldn't removing discussion of it and
instead only talking about datatypes make those documents shorter (at
least marginally) and easier to understand?

-Alan


>
> Btw, the RDF Semantics document introduced datatype maps years ago, stating
> in [2]:
>
>    "RDF provides for the use of externally defined datatypes
>    identified by a particular URI reference.
>    In the interests of generality, RDF imposes minimal
>    conditions on a datatype. It also includes a single
>    built-in datatype rdf:XMLLiteral."
>
> So supporting external datatypes beyond those shipped with the standard was
> clearly intended.
>
> Cheers,
> Michael
>
> [1]
> <http://www.w3.org/2007/OWL/wiki/Semantics#Independence_of_the_Semantics_fro
> m_the_Datatype_Map>
> [2] <http://www.w3.org/TR/rdf-mt/#dtype_interp>
>
>
Received on Friday, 12 September 2008 15:13:26 UTC

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