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Re: Contextualization ---> Optional bundle in Specialization

From: Graham Klyne <graham.klyne@zoo.ox.ac.uk>
Date: Wed, 27 Jun 2012 18:09:20 +0100
Message-ID: <4FEB3E40.6010901@zoo.ox.ac.uk>
To: Luc Moreau <L.Moreau@ecs.soton.ac.uk>
CC: Provenance Working Group WG <public-prov-wg@w3.org>
On 27/06/2012 10:49, Luc Moreau wrote:
 > All,
 >
 > At the face to face meeting, we have agreed to rename contextualization and mark
 > this feature
 > at risk. Tim, Stephan, Paul and I have worked a solution that we now share with
 > the working group.

I'm afraid I still have a problem with this.

Considering your bundle tool:analysis01:
[[
bundle tool:analysis01
     agent(tool:Bob-2011-11-16, [perf:rating="good"])
     specializationOf(tool:Bob-2011-11-16, ex:Bob, ex:run1)

     agent(tool:Bob-2011-11-17, [perf:rating="bad"])
     specializationOf(tool:Bob-2011-11-17, ex:Bob, ex:run2)
endBundle
]]

The problem is that, if subject to RDF semantics for URI interpretation, I can 
see no semantic distinction is possible between

   tool:Bob-2011-11-16
and
   tool:Bob-2011-11-17

I.e. they are both specializations of ex:Bob, and that is all we can know about 
them, as (by the nature of the semantics of URI interpretation) the denotation 
of ex:Bob that appears in ex:run1 is the same as the denotation of ex:Bob that 
appears in ex:run2.

...

I do, however, have a different compromise that provides a hook for introducing 
possible semantics later, or in private implementations, without sneaking in 
something that could well turn out to be incompatible with, or just different 
than, what the RDF group may do for semantics of datasets.

The hook is this: simply allow attributes for the specializationOf relation, but 
don't define a specific attribute for bundle.  This would allow you to do a 
private implementation of the scheme you describe, but would not allow it to be 
mistaken for something that has standardized semantics.  As in:

   specializationOf(tool:Bob-2011-11-17, ex:Bob,
                    [myprivateattribute:bundle=ex:run2])

...

In case you think I'm jumping at shadows here, I'll note that RDF has been here 
before.  The original 1999 RDF specification described reification without 
formal semantics.  Reification was intended to allow for capturing this kind of 
information - i.e. to make assertions about context of use, etc - a kind of 
proto-provenance, if you like.  But when the group came to define a formal 
semantics for RDF, there were two possible, reasonable and semantically 
incompatible approaches; looking at the way that reification was being used "in 
the wild", it turned out that there was data out there that corresponded to both 
of these (incompatible) approaches.  This was in the very early days of the 
semantic web, so the harm done was quite limited.  I think a similar mistake 
today would cause much greater harm.

I think the appropriate way forward is to take this tool performance analysis 
use-case to the RDF-PROV coordination group, and ask that it be considered as 
input when defining semantics for RDF datasets.  I would expect that whatever 
semantic structure they choose, it should be able to accommodate the use-case. 
Then, we should be better placed to create an appropriate and compatible 
contextualization semantics for provenance bundles.  But until then, I think we 
invite problems by trying to create a standardized data model structure without 
standardized RDF-compatible semantics to accommodate this use-case.

#g
--

Tracker, this is ISSUE-385

On 27/06/2012 10:49, Luc Moreau wrote:
> All,
>
> At the face to face meeting, we have agreed to rename contextualization and mark
> this feature
> at risk. Tim, Stephan, Paul and I have worked a solution that we now share with
> the working group.
>
> Given that contextualization was already defined as a kind of specialization, we
> now allow an optional
> bundle argument in the specialization relation. (Hence, no need to create a new
> concept!)
>
> See section 5.5.1 in the current Editor's draft
> http://dvcs.w3.org/hg/prov/raw-file/default/model/prov-dm.html#term-specialization
>
> Feedback welcome.
>
> Regards,
> Luc
>
> PS. Tracker, this is ISSUE-385
>
Received on Wednesday, 27 June 2012 17:13:49 UTC

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