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Re: Datatyping issue, too many options?

From: Pat Hayes <phayes@ai.uwf.edu>
Date: Sat, 16 Mar 2002 16:53:01 -0800
Message-Id: <p05101417b8b996e415d2@[65.212.118.252]>
To: Graham Klyne <GK@NineByNine.org>
Cc: w3c-rdfcore-wg@w3.org
>I can't remember if we agreed this was an issue:
>
>The latest datatyping proposal [1] provides three different ways to 
>apply datatyping:
>
>(1) Sections 1, 5:
>
>    ex:Jenny ex:age "10" .
>    ex:age rdfs:drange datatype:decimal .
>
>(2) Section 3:
>
>    ex:Jenny ex:age _:x .
>    _:x datatype:decimal "10" .
>
>(3) Section 5:
>
>    ex:Jenny ex:age _:x .
>    _:x rdfs:dlex "10" .
>    ex:age rdfs:drange datatype:decimal .
>
>I think that options (1) and (2) cover the use cases that have been 
>put forward.  I don't recall a use-case that needs (3), so this may 
>be an issue to the extent that the proposal goes to some additional 
>effort to support more options than may be really needed.

3 is the case that corresponds to the version of idiom (1) where a 
literal can denote its value. That was the original P-style idiom 
which is used in DAML, for example. We have ruled out the P idiom, 
but case (3) above is its substitute.  I think we need this in order 
to be able to do range datatyping properly.  It isnt really fair to 
say that (1) and (3) are alternative *ways* to do datatyping: they 
are the same way, but used for different purposes. (1) imposes a 
check on lexical forms, (3) assigns a value based on the form.

>
>(This presumes a slight weakening of one of the stated desiderata 
>concerning uniform application of "local" and "global" typing 
>idioms.  Effectively, option (1) is a "global" (or "remote") 
>mechanism, which can also be applied locally.  Option (2) is a 
>strictly local mechanism.  (3) might be viewed as a "global" (or 
>"remote") variant of (2).)
>
><aside>
>
>(4) Another option, not explicitly part of the datatyping spec, but 
>noted here for completeness since this is implicated by the 
>non-datatyping elements of RDF schema:
>
>    ex:Jenny ex:age _:x .
>    _:x rdf:type datatype:decimal .
>     :
>    (other properties for _:x, etc.)

Right, but in this proposal, that would NOT invoke any particular 
datatype checks. It just uses normal RDF schema reasoning about a 
class which happens to be the one used by a datatype.

>
>which would be rdfs-entailed by:
>
>    ex:age rdfs:range datatype:decimal .
>    ex:Jenny ex:age _:x .
>     :
>    (other properties for _:x, etc.)
>
></aside>
>
>....
>
>A very much lesser possible issue:  is the name "rdfs:drange" 
>appropriate for its use to indicate allowable lexical forms?

Well, I suggested that we change it to rdfs:dcrange in order partly 
to make it even less similar to rdfs:range. The 'range' part does 
make some sense, since it applies to the object of the property 
rather than the subject, but I agree it is potentially confusing.

Pat
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Received on Monday, 18 March 2002 15:05:11 EST

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