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

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 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
>>
>
>