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Re: Clarifications needed for the Collection construct (with CR)

From: Karsten Tolle <tolle@dbis.informatik.uni-frankfurt.de>
Date: Tue, 25 Feb 2003 21:20:57 +0100
Message-ID: <000001c2dd6f$8b084ac0$230b028d@HANNOVER>
To: "pat hayes" <phayes@ai.uwf.edu>, "Graham Klyne" <GK@ninebynine.org>
Cc: <www-rdf-comments@w3.org>

----- Original Message -----
From: "Graham Klyne" <GK@ninebynine.org>
To: "pat hayes" <phayes@ai.uwf.edu>
Cc: "Karsten Tolle" <tolle@dbis.informatik.uni-frankfurt.de>;
Sent: Tuesday, February 25, 2003 1:53 PM
Subject: Re: Clarifications needed for the Collection construct (with CR)

> At 05:43 PM 2/21/03 -0600, pat hayes wrote:
> >>Would it not make more
> >>sense to enter a rdf:Bag instead? But there is also another question: Do
> >>need the collection construct at all?
> >
> >It was specifically requested by the Webont working group, as a necessary
> >requirement for OWL. So the answer is yes.
> I have also found in my own use of RDF that it is sometimes important to
> have a collection construct that is "closed";  i.e. to which no new
> elements can be added through RDF graph merging.  Not having this would
> make it impossible (I think) to express certain things without violating
> the basic RDF semantics.
> #g

As you can read in my notes (and also in the comments of Pat), that
collections per se
are not "closed".

> At 05:43 PM 2/21/03 -0600, pat hayes wrote:
> >>The effect is that by entering a non-blank node someone could enter also
> >>to the collection construct elements from outside. This means without
> >>any restrictions this construct is not fixed!
> >Right, it is not. Nothing is 'fixed' in this sense in RDF.

The constructs collection or container are only "closed" or "fixed" when
blank nodes are used.

> -------------------
> Graham Klyne
> <GK@NineByNine.org>
Received on Wednesday, 26 February 2003 03:16:00 UTC

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