W3C home > Mailing lists > Public > w3c-rdfcore-wg@w3.org > January 2002

Re: RDF datatyping goals (action from teleconference)

From: Patrick Stickler <patrick.stickler@nokia.com>
Date: Tue, 15 Jan 2002 17:32:42 +0200
To: ext Graham Klyne <Graham.Klyne@MIMEsweeper.com>
CC: Jeremy Carroll <jjc@hplb.hpl.hp.com>, RDF Core <w3c-rdfcore-wg@w3.org>
Message-ID: <B86A183A.BA45%patrick.stickler@nokia.com>
On 2002-01-15 17:02, "Patrick Stickler" <patrick.stickler@nokia.com> wrote:

> On 2002-01-15 14:38, "ext Graham Klyne" <Graham.Klyne@MIMEsweeper.com> wrote:
>> At 09:45 AM 1/15/02 +0200, Patrick Stickler wrote:
>>> The semantics of the rdfs:range 'constraint' (as I see it) is to
>>> define an implicit union of data types, the members being the objects
>>> of the rdfs:range, which may be used to
>> "intersection", not "union" (per WG resolution).
> ??? I understood that 'union' meant the intersection of
> lexical and value spaces.
> What's the difference?

Ahhh, OK, I think I see where your coming from.

A Union Datatype expects that its members are a member of
at least one, but not all, of its subtypes.

But the rdfs:range constraint defines an intersection of types
(not union) such that a lexical form (property value) is
considered (or required) to be a member of every specified
type -- and of course, any of those types can be a Union

Thus, I can define a Union Datatype 'myUnion' with xsd:date and
xsd:duration, which have totally disjunct lexical spaces, and I can
then say

  ex:someProp rdfs:range xsd:string .
  ex:someProp rdfs:range #myUnion .

which will never result in a contradition since xsd:string subsumes
the lexical space of all lexical datatypes.

Yet if I say

  ex:someProp rdfs:range xsd:date .
  ex:someProp rdfs:range xsd:duration .

then I am sure to get a contradition every time, regardless of
whether the literal is a valid xsd:date or xsd:duration since
all rdfs:range defined types are inferred/required.


If so, then I'm OK with your definition of the equality of (a), (b),
and (c) with regards to interpretation.


Patrick Stickler              Phone: +358 50 483 9453
Senior Research Scientist     Fax:   +358 7180 35409
Nokia Research Center         Email: patrick.stickler@nokia.com
Received on Tuesday, 15 January 2002 10:32:02 UTC

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