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Re: Datatyping desiderata, take 2

From: Patrick Stickler <patrick.stickler@nokia.com>
Date: Thu, 17 Jan 2002 15:18:10 +0200
To: ext Martyn Horner <martyn.horner@profium.com>, Graham Klyne <GK@NineByNine.org>
CC: RDF Core <w3c-rdfcore-wg@w3.org>
Message-ID: <B86C9BB2.BC02%patrick.stickler@nokia.com>
On 2002-01-17 14:34, "ext Martyn Horner" <martyn.horner@profium.com> wrote:

> ...it
> seems to me also that 7 restates 5 and 6

I think that we need 7 as well as 5 and 6. All three are distinct. It may
be the case that one is satisfied with either only local typing or
only global typing in a particular knowledge base, in which case
cohabitation (#7) is irrelevant. What 7 says is
that in addition to providing for local and for global typing, we
would like to see those two mechanisms coexist in the same knowledge
base without undesirable interaction.

> that 4 follows from 3

I understand 4 to mean (and Graham, please correct me if I'm wrong)
that we wish to be able to describe the characteristics of lexical
datatypes in terms of RDF, such as relations between datatypes
and possibly the nature of their lexical and/or value spaces, rather
than leaving such issues completely implicit and up to each
application to provide native support for.
 
> Also, I lost the point of the list of idiom examples: idiom B and idiom
> P are shown to be the same (modulo prefix). Have I missed something?

They are almost, but not quite the same. In the P idiom, the
rdfs:range value is a URI that denotes the entire datatype,
whereas in the B idiom, the value is a URI that only denotes
the lexical space of a datatype. In the S proposal, the
type URI is given a suffix '.lex' (e.g. ex:date.lex). Is there
perhaps an error in the example for B? Should it be 'ex:date.lex'
rather than 'ex:date'? The same question comes to mind for the
example for A -- should it be 'ex:date.map' rather than 'ex:date'?

It occurs to me that perhaps the common desiderada should not
attempt to summarize the different idioms, as they tend to depend
on an understanding of each particular datatyping scheme, but
that it should be left to each proposal to describe the idioms
employed/recommended, with such descriptions given in terms of
the semantics of each scheme.  I.e., it is only by understanding
the S scheme that one knows that ex:date in idiom A refers to
the mapping (not the lexical space or value space) of the
datatype and in idiom B it refers to the lexical space, etc.

The different namespaces 'ex[ABPD]:', I understand, attempt
to hint at such distinctions, but IMO end up confusing matters
even more since exP = exD but exA != exB, etc.

Cheers,

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 Thursday, 17 January 2002 08:17:29 EST

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