Re: PROV-ISSUE-1 (define-resource): Definition for concept 'Resource' [Provenance Terminology]

James, Graham (will address Luc's comments on the wiki again separately)

I would argue that the provenance of the car includes all the engine replacements that took place, so if the engine is now B, I 
would like to ask the question "why is B here?" and receive an answer like "B has replaced A [at time t] [because A failed...]". I 
believe James hinted at this. And if you are interested, you go back and unfold the history of A. So yes, the provenance of A is 
still part of the car's provenance, in the car's current state -- the logbook of car repairs that you get from your garage is a 
simple example.
All I meant to say is that history is cumulative and immutable. That is not to say it's linear. Someone else (sorry, mail chaos at 
this point) commented that it is a DAG, and I would agree without having thought too hard (which I never do :-)).
   The issue of scoping / avoiding the big bang problem is addressed separately: you may decide to prune the early episodes in 
history for convenience, engineering issues, etc., and for most resources (whatever your definition), there is some kind of origin. 
It's often relative to the observer (as is all provenance): consumers generally don't need to investigate where the engine's 
materials come from, whereas a forensic epert investigating an engine failure may.

In my view, Theseus's ship is the result of all the actions that were ever taken on it, including the destructive ones. Too radical?

--Paolo


On 6/2/11 12:41 PM, James Cheney wrote:
> Yes, these issues seem intuitive only as long as you don't stop to think about them too hard :)
>
> I would say that the provenance has to be scoped by (say) a start and end time, or some other criterion, to prevent the "big bang" 
> problem (see e.g. [Miles IPAW 2006]).
>
> If we want the provenance of the car from "now" until it was made, then the provenance of A needs to be included (e.g., maybe A 
> caused damage to the car when it failed, so we need to know that to understand how the car's current state was obtained from its 
> initial state).
>
> If we want the provenance of the car from "now" until I bought it, which happened after the engine was replaced, then maybe I 
> don't need to know about A.  (If I want to buy the car, I'd probably value the knowledge of the earlier history so that I can 
> understand its current state, but the seller isn't always obligated to provide this.)
>
> This reminds me of another good story:
>
> /The ship wherein Theseus <http://en.wikipedia.org/wiki/Theseus> and the youth of Athens <http://en.wikipedia.org/wiki/Athens> 
> returned [from Crete <http://en.wikipedia.org/wiki/Crete>] had thirty oars, and was preserved by the Athenians down even to the 
> time of Demetrius Phalereus <http://en.wikipedia.org/wiki/Demetrius_Phalereus>, for they took away the old planks as they decayed, 
> putting in new and stronger timber in their place, insomuch that this ship became a standing example among the philosophers 
> <http://en.wikipedia.org/wiki/Philosopher>, for the logical question of things that grow; one side holding that the ship remained 
> the same, and the other contending that it was not the same./
> —Plutarch, /Theseus [http://en.wikipedia.org/wiki/Ship_of_Theseus]/
> /
> /
> What is the provenance of the ship?  Was the ship really "preserved"?
>
> --James
>
> On Jun 2, 2011, at 12:05 PM, Graham Klyne wrote:
>
>> I think Paolo has usefully threaded a path through our discussions.  Thanks!  At first reading, I would consent (in the sense of 
>> "consensus") to definitions framed on the basis of what he has written here.
>>
>> ...
>>
>> The issue of monotonicity (of provenance of a stateful resource) is interesting. Intuitively, it seems appropriate, but I'd need 
>> to let it stew awhile before accepting it unconditionally.  My immediate concern is how do we account for correction of previous 
>> errors in provenance claims?  But this question goes to the heart of what is, IMO, one of the key purposes of provenance on the 
>> Web (i.e. to help deal with conflicting information in the Web, and the Semantic Web in particular), so maybe that point gets 
>> addressed separately in any case.
>>
>> Aha!  I just thought of another example:  suppose we're talking about provenance of a car (e.g. for QA purposes).  Initially, 
>> suppose it has engine A, made by a particular factory.  The provenance of the car include the provenance of engine A.  Sometime 
>> in its life, the engine fails and is replaced by engine B, and provenance of engine C becomes part of the car's provenance.  At 
>> this point, does it make sense to claim that the provenance of A is still part of the car's provenance?  A similar example could 
>> be constructed for, say, a photo album where images are added and removed.
>>
>> #g
>> --