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Re: PROPOSALS TO VOTE ON (deadline: Wednesday 14th, midnight GMT)

From: Curt Tilmes <Curt.Tilmes@nasa.gov>
Date: Mon, 12 Mar 2012 09:52:24 -0400
Message-ID: <4F5DFF98.4080107@nasa.gov>
To: <public-prov-wg@w3.org>
On 03/09/2012 09:41 AM, Luc Moreau wrote:
> Please express your vote for each proposal separately:
> http://dvcs.w3.org/hg/prov/raw-file/default/model/working-copy/wd5-prov-dm-misc.html#proposal1

I'm still not quite sure what this concept (tentatively called
'invalidation') really means.

You're trying to define "end of lifetime" as "unavailable for usage",
but that seems to be a tough thing to enforce.  What if someone else
uses it anyway?  Can they no longer assert usages of that entity?
What does that mean?  Is their provenance no longer consistent with
the model?


On 03/12/2012 06:09 AM, Luc Moreau wrote:
> The first entity was the one at http://www.w3.org/TR/prov-dm/
> entity(tr:prov-dm,[prov:type="working draft", ex:version="1"]) which
> is no longer version 1, when v2 comes out at the same url.

Regardless of the availability of the the content represented by an
entity through a URL, we aren't allowed to use the same URI to refer
to two different characterized entities. (Is that true?)  If something
changes to affect that characterization, we must create a new URI to
distinguish the new thing from the old thing.

The mere existence of tr:WD-prov-dm-20111215 doesn't preclude some
activity 'using' tr:prov-dm (couldn't they still retrieve its content
from someplace else?)


I think this use case could better be accomodated by a distinct
concept "prov:SupercededBy" (do we already have something like that --
I seem to recall that coming up before?), but I still see that as an
advisement "You *should* use the later version" -- not "You *can't*
use the old version." that makes any assertion of a usage of the old
version inconsistent with the model.



The second example tries even harder to make it simply impossible for
someone to have used chicago:wkshp2002, but I still think
disappearence of the information from the URL is a weird way to do
that.

I guess if one of the attributes characterizing the entity with the
URI chicago:wkshp2002 is its existence at that URL, then while the
proceedings themselves may still exist somewhere, in some form, the
entity represented by that particular characterization, referred to by
that specific URI no longer does exist.


So if I, for example, download those proceedings prior to their
disappearance, then at some later time, perform some activity based on
those proceedings, while my activity "used" the proceedings
themselves, it doesn't (can't) use the entity chicago:wkshp2002, which
no longer exists.

Too weird.


Curt

-- 
Curt Tilmes, Ph.D.
U.S. Global Change Research Program
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Washington, D.C. 20006, USA

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Received on Monday, 12 March 2012 13:53:03 GMT

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