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

From: Timothy Lebo <lebot@rpi.edu>
Date: Tue, 22 Nov 2011 12:53:06 -0500
Cc: Graham Klyne <graham.klyne@zoo.ox.ac.uk>, Paul Groth <p.t.groth@vu.nl>, Stephan Zednik <zednis@rpi.edu>, Provenance Working Group WG <public-prov-wg@w3.org>
Message-Id: <0214D282-779A-4244-9C1B-E97B9C2FBC58@rpi.edu>
To: Luc Moreau <L.Moreau@ecs.soton.ac.uk>

On Nov 10, 2011, at 12:34 PM, Luc Moreau wrote:

> 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.

As long as this is explicit (it is in the latest draft), then DM is providing the flexibility that PROV-O needs.

> 
> But feedback indicated that it was not.


The feedback was "It is not clear that we can make URIs out of DM's literals - we are worried that we can only make RDFS Literals"

But the statements in DM make it clear that we can.

"A PROV-DM Literal represents a value whose interpretation is outside the scope of PROV-DM."
"in either case; such URI has no specific interpretation in the context of PROV-DM."

-Tim



> So, where are we standing on this?
> 


We can close this issue.

-Tim




> 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 Tuesday, 22 November 2011 17:54:12 UTC

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