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

From: Luc Moreau <L.Moreau@ecs.soton.ac.uk>
Date: Fri, 10 Jun 2011 08:26:01 +0100
Message-ID: <EMEW3|586d72e14d6f3ab51dc9c52da0130916n598R308L.Moreau|ecs.soton.ac.uk|4DF1C709.2070802@ecs.soton.ac.uk>
To: "Myers, Jim" <MYERSJ4@rpi.edu>
CC: public-prov-wg@w3c.org
Hi Jim,

I had not seen your comment in line, my responses are also inline.

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 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?
>    

I would think the physical object is the egg.
I thought we had agreed that for a provenance purpose, we had to talk 
about an IVPT of that 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?
>    

These comments were made in the context of defining Generation of an IVPT.

The document was edited four times could be expressed by 4 process 
execution and something like opm:wasTriggeredBy in between.

> - 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.
>    

Yes, agreed.

> - 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.
>    
I am not sure I agree, here. IVPTs are a view/perspective on a thing.

Alternative views asserted by other asserters may co-exit.
- it's a decaying egg
- it's a duck egg, not a hen egg
- it's a chocolate egg

It is a requirement of any specific perspective to be invariant.
So, it's not a snapshot of the global egg state, but it's a snapshot 
according to a view.

An analogy would be several cameras pointing to a same egg.
 From one camera, the egg is still, no change occurring.
 From the other, we see a crack appearing.
So one asserter can describe change in a physical object, while another 
does not describe any change.
But it's the same egg.

Luc
> 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 07:27:33 GMT

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