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Re: A proposed provenance wg draft charter

From: Paolo Missier <pmissier@acm.org>
Date: Mon, 25 Oct 2010 16:29:08 +0100
Message-ID: <4CC5A244.8030702@acm.org>
To: Olaf Hartig <hartig@informatik.hu-berlin.de>
CC: public-xg-prov@w3.org
Olaf,
>> why wouldn't resources have provenance?
> The problem is that a Web resource may change; it may have a different state at
> a different point in time. What would the provenance of such a changing thing
> be?
well, if a resource changes its state, I would assume that its provenance will actually account for those state changes? isn't that 
within the scope of its model?
> A specific representation of a Web resource cannot change. That's why I find it
> much easier to talk about the provenance of such representations rather than
> the Web resource itself.
> That's probably also why artifacts in OPM are immutable pieces of state.
ok, but in my mind artifacts (in the OPM sense, for example) stand for resources, rather than their representations.
maybe I don't quite understand what you mean by a representation of a resource, here. If a resource changes its state, wouldn't its 
representation (whatever it is) change as well?

I would find it natural to talk about data versioning (accounting for state changes) along with data dependencies (amongst specific 
versions of a set of resources), within the same provenance framework.
>> just like a piece of data in a database.
> In the case of a database I would also prefer to associate provenance with
> manifestations of the data. For instance, given a table, I would not associate
> provenance with the table per se but with a specific version / state of the
> table. Same with a cell in such a table: I would associate provenance with a
> specific attribute value thats in the cell rather than with the cell itself.
sure, although these two are not the same example: the former is associating provenance to a version, which is pretty much what I 
was implying above, while the latter is a matter of granularity within the same state -- but I agree that both should be there
>> I see it the opposite way: isn't the provenance of a
>> manifestation of a resource is just (some view of) the provenance of the
>> resource itself?
> I wouldn't say so. What you say would mean that multiple different
> manifestations of the same (state of the same) Web resource have the same
> provenance (even if different views on it). Shouldn't they have different
> provenance (even if several pieces of their provenance are overlapping)?
> Let's say, both of us retrieve a representation of a Web resource; we do it at
> the same point in time; so, if we are lucky, we have two representations that
> represent the Web resource in the same state. Nonetheless, I think these two
> representations have different provenance.
ok, but isn't their difference "only" in the last, retrieval step? they effectively represent the same resource, under the retrieval 
conditions you describe, only the last access step changes, and it's not clear to me that that is part of the resource's provenance

interesting thread, anyway -- not sure it will have an impact on the proposed charter though :-)

-Paolo
Received on Monday, 25 October 2010 15:29:39 GMT

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