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

From: Khalid Belhajjame <Khalid.Belhajjame@cs.man.ac.uk>
Date: Fri, 10 Jun 2011 19:30:18 +0100
Message-ID: <4DF262BA.4040600@cs.man.ac.uk>
To: Graham Klyne <GK@ninebynine.org>
CC: Luc Moreau <L.Moreau@ecs.soton.ac.uk>, "Myers, Jim" <MYERSJ4@rpi.edu>, public-prov-wg@w3c.org

Hi Graham,

I find the issues discussed in this thread interesting. That said, I am 
not sure I have a convincing answer to your question. A simple example 
that justifies the need for it though is:

"tell me the history of a given egg"

To answer the above query, you need to know what are the IVPTs that are 
represents views on the same egg.

Thanks, khalid

On 10/06/2011 18:16, Graham Klyne wrote:
> 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/
>
> #g
> -- 
>
>
> 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 18:30:52 GMT

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