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

From: Luc Moreau <L.Moreau@ecs.soton.ac.uk>
Date: Thu, 10 Nov 2011 17:34:09 +0000
Message-ID: <EMEW3|3811151dbaabcda4aaca1e684c63eea8nA9HYC08L.Moreau|ecs.soton.ac.uk|4EBC0B11.6070704@ecs.soton.ac.uk>
To: Graham Klyne <graham.klyne@zoo.ox.ac.uk>
CC: Paul Groth <p.t.groth@vu.nl>, Stephan Zednik <zednis@rpi.edu>, Provenance Working Group WG <public-prov-wg@w3.org>
Hi Graham,

My very original idea was to use Strings for roles, because some 
(non-SW) users
may just want to use a string to say "person".

My second idea was also to allow URIs, which is what the SW people would 
have used.
e.g. "foaf:person"

Beyond roles, parameter positions may also be encoded as an index.

Hence, the choice of typed literal.  They do have fixed denotations.

I felt this was enough. I still feel this is enough.

The Prov-O team would have had the flexibility to translate a prov-dm 
Literal to whatever
they felt appropriate.

But feedback indicated that it was not.

So, where are we standing on this?

Luc



On 11/10/2011 02:25 PM, Graham Klyne wrote:
> 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.
>

-- 
Professor Luc Moreau
Electronics and Computer Science   tel:   +44 23 8059 4487
University of Southampton          fax:   +44 23 8059 2865
Southampton SO17 1BJ               email: l.moreau@ecs.soton.ac.uk
United Kingdom                     http://www.ecs.soton.ac.uk/~lavm
Received on Thursday, 10 November 2011 17:34:47 UTC

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