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

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.


Paolo Missier wrote:
> All
> ok, so far I have been able to catch up with the Resource ISSUE 1, and 
> believe me it took a while.  I have not digested anything else.
> It seems that some consensus is emerging, so let me throw in my 2 cents 
> as a summary of my understanding +more questions, hoping not
> to undo progress that has been made on this.
> Summary:
> =======
> I seem to see a consensus that resources have, or can be given, an 
> identity:
>   >   - For our purposes, a resource is anything which can be referred 
> to  (SM)
> there is also a discussion on whether an Information Object has the same 
> resource status as a resource as a physical object, but I
> wouldn't be able to add to that discussion. To me, the objects that 
> matter are primarily data structures,  documents, and
> assertions, and I think what we are saying does apply to those.
> I also agree with SM, GK, etc. that
>   >   - When we talk about the provenance of a resource, we mean the
>   >  provenance of its state on asking the question.
> so we also agree that there is an implicit notion of resource state:
> - resource state ->  r-snapshot   (LM)
> and I personally agree that any notion of provenance refers to a 
> specific state of a resource.  Naturally here we mean "observable
> state". I have not seen the notion of observer introduced in this 
> discussion (I have yet to catch up with the others!), but it seems
> natural that provenance is relative to an observer.
> - the fact that the Web architecture defines its foundational concepts 
> similarly should be viewed as a convenience which will help
> ground the concepts, rather than a set of constraints that we are bound to.
> Additionally:
> ========
> - can we also assume that provenance is /monotonic/ wrt the state 
> evolution of the resource it refers to.
> This is desirable (for computational purposes) and seems to follow 
> naturally from associating provenance to a state: let r_s be a
> resource r in state s. Its provenance prov(r_s) is a subset of 
> prov(r_{s'}) for any s' that temporally follows s. yes?
> - Given a resource r in a state s: r_s, one can create one or more 
> representations ("manifestations") repr(r_s) of r_s. These are
> all r-snapshots or r_s.
> - importantly, Jun writes:
>   >  If f1 is a file, then it is a representation of a resource, not a
>   >  resource any more, right?
> I would argue that  repr(r_s) *should be a resource itself*, for any 
> resource r and (visible) state s. Indeed, it has an initial
> state (the time it is created from the underlying resource state), and 
> its provenance at that state is simply the provenance of r_s,
> plus the action of creating repr(r_s).   Then It can then evolve 
> independently (but monotonically) as that new representation is
> acted upon. The provenance of any further state, is prefixed by that 
> just mentioned by monotonicity.
> Containers:
> ======
> I do have a problem with "containers" as a separate notion from 
> resource, however.
> Isn't a database a container? and a resource? (it does have a state, 
> which is the set of all its elements, and for a given state I
> can certainly exhibit the provenance of each data item it contains).
> So I am not sure the notion of container is useful here, or even 
> well-founded:  you end up with issues of granularity, because
> containers may be nested. But then anything non-atomic, like a tuple, is 
> a container, which however does have a provenance, as we know.
> Oh, well. Just more noise, perhaps.
> Regards,
>     -Paolo

Received on Thursday, 2 June 2011 11:27:28 UTC