W3C home > Mailing lists > Public > www-rdf-logic@w3.org > February 2002

Re: reification test case

From: Pat Hayes <phayes@ai.uwf.edu>
Date: Mon, 4 Feb 2002 15:04:48 -0600
Message-Id: <p05101404b884a64ce323@[]>
To: "Seth Russell" <seth@robustai.net>
Cc: www-rdf-logic@w3.org
>From: "Peter F. Patel-Schneider" <pfps@research.bell-labs.com>
>>  There are arguments to be made on either side.  Some argue that there
>>  should be multiple reifications, some argue that there should not. Given
>>  that there are two viable possibilities, and that RDF M&S clearly comes
>>  down on one side, switching to the other is a significant change, and
>>  should not be made lightly.
>That's just your opinion; I believe there are lawyers who could argue
>persuasively against it.
>>  > But the essential requirement that you will need to answer is not a
>>  > legalistic one, but a practical one.  If you throw out the ability to
>>  > multiple descriptions of statements, then how are we to describe
>>  > occurances of the same proposition relative to the contexts in which
>>  > appear?
>>  Well I guess then you can't, at least not with RDF reification.
>This is unacceptable and will break running applications and will render
>planned applications impossible.

Break what running aps? There is no notion of 'context' in RDF1.0 in 
any case, so I fail to see how it could possibly break any app that 
was using the current spec.

What kind of app would need multiple reifications of a triple in the 
same graph? It would be fine to give the reification a URI by some 
external naming convention, and then have multiple RDF descriptions 
referring to it. Would that suffice?

Any decision we take will render SOME future apps impossible, by the way.

>>  RDF reification is what is described in RDF M&S.  It may not be very
>>  useful but that doesn't mean that RDF reification should be something
>>  different from what is described in RDF M&S.  (There are enough unclear
>>  aspects of RDF M&S to argue over without changing the clear parts.)
>You may say it is clear to you, but it has been pointed out that M&S is
>inconsistent in that regard.  The working group has been chartered to fix
>these confusions. We are not still back there in 1999 arguing about a
>literal interpretation of the M&S bible.
>It seems to me that those in favor of a one-one mapping between a
>proposition and the description of that proposition are trying to limit the
>usefulness of RDF.  For what purpose, to what end ?

The WG has a chartered responsibility to only make changes that are 
required in order to fix problems, not to design a perfect RDF. 
(There may be an RDF 2.0 later, designed by a diffferent WG.) . Its 
not obvious to me that having one reification per triple constitutes 
a fatal problem.

Pat Hayes

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Received on Monday, 4 February 2002 16:04:17 UTC

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