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Re: PROV-ISSUE-142 (Tlebo): Can roles only be Literals? [Data Model]

From: Graham Klyne <graham.klyne@zoo.ox.ac.uk>
Date: Thu, 10 Nov 2011 14:25:12 +0000
Message-ID: <4EBBDEC8.8060202@zoo.ox.ac.uk>
To: Paul Groth <p.t.groth@vu.nl>
CC: Luc Moreau <L.Moreau@ecs.soton.ac.uk>, Stephan Zednik <zednis@rpi.edu>, Provenance Working Group WG <public-prov-wg@w3.org>
On 06/11/2011 19:04, Paul Groth wrote:
> This is where the confusion is. Literals in RDF-speak are not URIs. Maybe a note in either prov-o or prov-dm would help clarify this.

Yes.

Referring to the model theoretic style of semantics used for RDF (and also for 
formalizing first order logic - if DM is appealing to some different semantic 
framework, this needs to be spelled out):

Specifically literals have a fixed denotation.  A plain string denotes itself. 
In integer literal denotes the number determined according to the numeric 
encoding scheme, a URI literal denotes a URI (*), etc...

By contrast, names (i.e. URIs in RDF) denote whatever some "interpretation" says 
they denote.  This interpretation is just a function from names to things, which 
is not fixed by the language.  The associated semantics (inherent and/or 
additionally defined) constrain the interpretations that are considered valid 
(also known as "models").

What this all means is that if something is a literal, you can't arbitrary say 
it denotes the American president known as "Barack Obama" (unless such a mapping 
is baked into an underlying literal structure, which doesn't really make sense).

Where this all leads is that I think the roles in DM should be names, not literals.

#g
--

(*) ... as opposed to a URI-node in RDF, which denotes whatever the applicable 
interpretation says it denotes.
Received on Thursday, 10 November 2011 16:16:58 UTC

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