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Re: PROV-ISSUE-8: defining generation in terms of `IVPT of'

From: Graham Klyne <GK@ninebynine.org>
Date: Fri, 10 Jun 2011 18:16:54 +0100
Message-ID: <4DF25186.5020809@ninebynine.org>
To: Khalid Belhajjame <Khalid.Belhajjame@cs.man.ac.uk>
CC: Luc Moreau <L.Moreau@ecs.soton.ac.uk>, "Myers, Jim" <MYERSJ4@rpi.edu>, public-prov-wg@w3c.org
It's not clear to me yet that the model *needs* to distinguish these cases, even 
if we can recognize them.

My quote of the day comes from the schema.org debate:
"In my experience, metadata design efforts tend to fall into the trap of 
focusing more about what could be said about a topic rather than what needs to 
be said in order to support use cases of the consuming software."
-- Henry Sivonen, http://hsivonen.iki.fi/schema-org-and-communities/


Khalid Belhajjame wrote:
>    Hi Jim and Luc,
> I agree with Luc, Jim point is a good one. I find it more relevant to 
> derivation than generation, though. 
> Generally, derivation can be though of as a relationship that connects 
> an IVPT of a thing to another IVPT of the same or different thing. I can 
> only think of two options to deal with the point raised by Jim. Either:
> - we add a property to IVPT that identify the thing that the IVPT gives 
> a view about, or
> - specialize the derivation relationship, by creating two 
> sub-relationships that distinguish between the two cases.
> Personally, I prefer the second one, as it spares us the problem of 
> having to identify “thing”, at least for the moment.
> Thanks, khalid
> On 10/06/2011 08:09, Luc Moreau wrote:
>> Hi Jim,
>> *very* good questions, that's the essence of IVPT, I think.
>> I don't have answers, and need to think about this.
>> I was looking at Generation alone, you seem to allude to Derivation.
>> Their definitions may need to be drafted together.  I will think about 
>> this.
>> Luc
>> On 10/06/11 02:28, Myers, Jim wrote:
>>> This would mean that a heating process modifies an egg to create a 
>>> warm egg, it does not transform a cold egg into a warm egg?
>>> Or do you mean both - a process execution can turn one thing into 
>>> another, these things can be considered IVPTs of a thing that 
>>> participates in the process execution/ is modified by the process 
>>> execution? And in an open world assumption, a witness doesn't have to 
>>> report the modified thing or can decline to identify/report either of 
>>> things in IVPT roles depending on their ability to observe and the 
>>> use case they wish to enable?
>>> ________________________________
>>> From: public-prov-wg-request@w3.org 
>>> <mailto:public-prov-wg-request@w3.org> on behalf of Luc Moreau
>>> Sent: Thu 6/9/2011 6:44 PM
>>> To: Provenance Working Group WG
>>> Subject: PROV-ISSUE-8: defining generation in terms of `IVPT of'
>>> Hi all,
>>> - if a new thing is created, it is clear that we have a new IVPT of 
>>> that thing
>>> if a chicken creates an egg is it just an IVPT of an egg?
>>> - if the thing is modified, then it is a requirement that a new view 
>>> (IVPT) is generated ...
>>>         otherwise, it would still be a view that existed before
>>> can't I say the egg was heated without reporting its cold and warm 
>>> states? I.e. don't we want to be able to report that something was 
>>> modified without having to report the IVPTs? A document was edited 
>>> four times by different people but I don't wan't to/can't tell you 
>>> what each wrote at each stage?
>>> - if the process execution was taking a long time to modify/create 
>>> the thing, there is only one
>>>     instant at which the (invariant!) IVPT appears
>>> I thnk we could define it that way, but if a cracking process takes 
>>> time, saying the cracked egg appears instantaneously basically means 
>>> you want 'cracked egg' to be defined by some threshold - the cracked 
>>> egg might become more cracked over time ) invariant only in that it 
>>> is always above the threshold and the instance of the creation of the 
>>> IVPT relationship occurs ata  aspecific instant.
>>> - I think this captures well a stateful objects, where processes can 
>>> modify the object, resulting in
>>>     different IVPTs corresponding to the various states
>>> IVPTs are not a separate kind of thing and their invariance is 
>>> relative. If they are truly immutable sates/snapshopts, they can only 
>>> exist for an instant because some part of the state of the thing (a 
>>> part we may not care about such as age) will change immediately.
>>> What do you think?
>>> http://www.w3.org/2011/prov/wiki/ConceptGeneration#Definition_of_Generation_by_Luc 
>>> Cheers,
>>> Luc
Received on Friday, 10 June 2011 17:19:36 UTC

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