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Re: PROV-ISSUE-1 (define-resource): Definition for concept 'Resource' [Provenance Terminology]

From: Luc Moreau <L.Moreau@ecs.soton.ac.uk>
Date: Thu, 02 Jun 2011 12:32:22 +0100
Message-ID: <EMEW3|20854ad5503be15eb46a53b2d4266e5bn51CWR08L.Moreau|ecs.soton.ac.uk|4DE774C6.7040509@ecs.soton.ac.uk>
To: public-prov-wg@w3.org

Hi Graham and Paolo,

I had also commented on this issue on the Wiki
http://www.w3.org/2011/prov/wiki/Talk:ConceptResource

Luc

On 06/02/2011 12:05 PM, Graham Klyne wrote:
> I think Paolo has usefully threaded a path through our discussions.  
> Thanks!  At first reading, I would consent (in the sense of 
> "consensus") to definitions framed on the basis of what he has written 
> here.
>
> ...
>
> The issue of monotonicity (of provenance of a stateful resource) is 
> interesting. Intuitively, it seems appropriate, but I'd need to let it 
> stew awhile before accepting it unconditionally.  My immediate concern 
> is how do we account for correction of previous errors in provenance 
> claims?  But this question goes to the heart of what is, IMO, one of 
> the key purposes of provenance on the Web (i.e. to help deal with 
> conflicting information in the Web, and the Semantic Web in 
> particular), so maybe that point gets addressed separately in any case.
>
> Aha!  I just thought of another example:  suppose we're talking about 
> provenance of a car (e.g. for QA purposes).  Initially, suppose it has 
> engine A, made by a particular factory.  The provenance of the car 
> include the provenance of engine A.  Sometime in its life, the engine 
> fails and is replaced by engine B, and provenance of engine C becomes 
> part of the car's provenance.  At this point, does it make sense to 
> claim that the provenance of A is still part of the car's provenance?  
> A similar example could be constructed for, say, a photo album where 
> images are added and removed.
>
> #g
> -- 
>
>
> Paolo Missier wrote:
>> All
>>
>> ok, so far I have been able to catch up with the Resource ISSUE 1, 
>> and believe me it took a while.  I have not digested anything else.
>> It seems that some consensus is emerging, so let me throw in my 2 
>> cents as a summary of my understanding +more questions, hoping not
>> to undo progress that has been made on this.
>>
>> Summary:
>> =======
>> I seem to see a consensus that resources have, or can be given, an 
>> identity:
>>
>> >   - For our purposes, a resource is anything which can be referred 
>> to  (SM)
>>
>> there is also a discussion on whether an Information Object has the 
>> same resource status as a resource as a physical object, but I
>> wouldn't be able to add to that discussion. To me, the objects that 
>> matter are primarily data structures,  documents, and
>> assertions, and I think what we are saying does apply to those.
>>
>> I also agree with SM, GK, etc. that
>>
>> >   - When we talk about the provenance of a resource, we mean the
>> >  provenance of its state on asking the question.
>>
>> so we also agree that there is an implicit notion of resource state:
>>
>> - resource state ->  r-snapshot   (LM)
>>
>> and I personally agree that any notion of provenance refers to a 
>> specific state of a resource.  Naturally here we mean "observable
>> state". I have not seen the notion of observer introduced in this 
>> discussion (I have yet to catch up with the others!), but it seems
>> natural that provenance is relative to an observer.
>>
>> - the fact that the Web architecture defines its foundational 
>> concepts similarly should be viewed as a convenience which will help
>> ground the concepts, rather than a set of constraints that we are 
>> bound to.
>>
>> Additionally:
>> ========
>>
>> - can we also assume that provenance is /monotonic/ wrt the state 
>> evolution of the resource it refers to.
>> This is desirable (for computational purposes) and seems to follow 
>> naturally from associating provenance to a state: let r_s be a
>> resource r in state s. Its provenance prov(r_s) is a subset of 
>> prov(r_{s'}) for any s' that temporally follows s. yes?
>>
>> - Given a resource r in a state s: r_s, one can create one or more 
>> representations ("manifestations") repr(r_s) of r_s. These are
>> all r-snapshots or r_s.
>>
>> - importantly, Jun writes:
>>
>> >  If f1 is a file, then it is a representation of a resource, not a
>> >  resource any more, right?
>>
>> I would argue that  repr(r_s) *should be a resource itself*, for any 
>> resource r and (visible) state s. Indeed, it has an initial
>> state (the time it is created from the underlying resource state), 
>> and its provenance at that state is simply the provenance of r_s,
>> plus the action of creating repr(r_s).   Then It can then evolve 
>> independently (but monotonically) as that new representation is
>> acted upon. The provenance of any further state, is prefixed by that 
>> just mentioned by monotonicity.
>>
>> Containers:
>> ======
>>
>> I do have a problem with "containers" as a separate notion from 
>> resource, however.
>> Isn't a database a container? and a resource? (it does have a state, 
>> which is the set of all its elements, and for a given state I
>> can certainly exhibit the provenance of each data item it contains).
>>
>> So I am not sure the notion of container is useful here, or even 
>> well-founded:  you end up with issues of granularity, because
>> containers may be nested. But then anything non-atomic, like a tuple, 
>> is a container, which however does have a provenance, as we know.
>>
>> Oh, well. Just more noise, perhaps.
>>
>> Regards,
>>     -Paolo
>>
>>
>>
>
>

-- 
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, 2 June 2011 11:32:51 GMT

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