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Re: PROV-ISSUE-7 (define-derivation): Definition for Concept 'Derivation' [Provenance Terminology]

From: Khalid Belhajjame <Khalid.Belhajjame@cs.man.ac.uk>
Date: Thu, 02 Jun 2011 14:34:22 +0100
Message-ID: <4DE7915E.6040403@cs.man.ac.uk>
To: Graham Klyne <GK@ninebynine.org>
CC: Luc Moreau <L.Moreau@ecs.soton.ac.uk>, public-prov-wg@w3.org

Hi Graham,

 >I agree that many of the examples of derivation we have raised relate 
to resource states.  But if, as has been suggested by myself and others, 
resource states are themselves resources >(especially when named for the 
purposes of expressing a derivation), then such derivations can equally 
be regarded as relating resources.  I think that's more a difference of 
terminology than >fundamental.

Would it be fair then to say that in that view resources are immutable 
Which bring me to the question, do we want to express derivations 
between mutable resources, or that is just something that we should 
avoid at this point?

Thanks, khalid

> Where I think I may diverge from what you say is that I would not 
> limit such expressions of derivation to resources that happen to be a 
> state (or snapshot of state) of some resource.  I think defining that 
> distinction in a hard-and-fast way, that also aligns with various 
> intuitions we may have about derivation, may prove difficult to 
> achieve (e.g. as I think is suggested by Jim Meyers in 
> http://lists.w3.org/Archives/Public/public-prov-wg/2011Jun/0015.html 
> (*)).
> #g
> -- 
> (*) I just love the W3C mailing list archives - so easy to find links 
> to messages, and thus capture provenance!
> Khalid Belhajjame wrote:
>> Hi,
>>  From the discussion so far on derivation it seems that most people 
>> tend to define derivation between resource states or resources state 
>> representations, but not for resources.
>> My take on this is that in a context where a resource is mutable, 
>> derivations will mainly be used to associate resource states and 
>> resource states representations.
>> That said, based on derivations connecting resource states and 
>> resources state representations, one can infer new derivations 
>> between resources. For example, consider the resource r_1 and the 
>> associated resource state r_1_s, and consider that r_1_s was used to 
>> construct a new resource state r_2_s, actually the first state, of 
>> the resource r2. We can state that r_2_s is derived from r_1_s, i.e., 
>> r_1_s -> r_2_s. We can also state that the resource r_2 is derived 
>> from the resource r_1, i.e., r_1 -> r_2
>> PS: I added a defintiion of derivation within this lines to the wiki:
>> http://www.w3.org/2011/prov/wiki/ConceptDerivation
>> Thanks, khalid
>> On 01/06/2011 07:49, Luc Moreau wrote:
>>> Hi Graham,
>>> Isn't it that you used the duri scheme to name the two resource 
>>> states that exist in
>>> this scenario?
>>> In your view of the web, is there a notion of stateful resource? 
>>> Does it apply here?
>>> Thanks,
>>> Luc
>>> On 31/05/11 23:57, Graham Klyne wrote:
>>>> Luc Moreau wrote:
>>>>> Graham,
>>>>> In my example, I really mean for the two versions of the chart to 
>>>>> be available at
>>>>> the same URI. (So, definitely, an uncool URI!)
>>>>> In that case, there is a *single* resource, but it is stateful. 
>>>>> Hence, there
>>>>> are two *resource states*, one generated using (stats2), and the 
>>>>> other using (stats3).
>>>> Luc,
>>>> I had interpreted your scenario as using a common URI as you explain.
>>>> But there are still several resources here, but they are not all 
>>>> exposed on the web or assigned URIs.  I'm appealing here to 
>>>> anything that *might* be identified as opposed to things that 
>>>> actually are assigned URIs.   (For example, the proposed duri: 
>>>> scheme might be used - 
>>>> http://tools.ietf.org/id/draft-masinter-dated-uri-07.html)
>>>> (And the URI is perfectly "cool" if it is specifically intended to 
>>>> denote a dynamic resource.  A URI used to access the current 
>>>> weather in London can be stable if properly managed.)
>>>> (I think this is all entirely consistent with my earlier stated 
>>>> positions.)
>>>> #g
>>>> -- 
>>>>> Of course, if blogger had used cool uris, then, c2s2 and c2s3 
>>>>> would be different resources.
>>>>> Luc
>>>>> On 05/31/2011 02:25 PM, Graham Klyne wrote:
>>>>>> I see (at least) two resources associated with (c2):  one 
>>>>>> generated using (stats2), and other using (stats3).  We might 
>>>>>> call these (c2s2) and (c2s3). 
Received on Thursday, 2 June 2011 13:34:56 UTC

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