Re: PROV-ISSUE-466 (must-entities-invalidate): Must all entities invalidate? [prov-dm-constraints]

Hi Stian,

It feels that you are trying to reopen ISSUE-331 which you had agreed to 
close:

http://lists.w3.org/Archives/Public/public-prov-wg/2012May/0032.html

The following was agreed then:

http://dvcs.w3.org/hg/prov/raw-file/b9d2157889f7/model/optional.html

PROV-Constraints is only implementing what was agreed.
Is there new information to take into consideration?

Thanks,
Luc

On 08/08/12 10:31, Stian Soiland-Reyes wrote:
> On Mon, Aug 6, 2012 at 5:15 PM, Luc Moreau <l.moreau@ecs.soton.ac.uk> wrote:
>> In prov-dm, we say "Entities have a duration", and "An activity is something
>> that occurs over a period of time".
>> Those two inferences only reflect what we say in prov-dm.
> A duration does not have to be finite.  (IMHO). Of course, practically
> this would primarily only make sense for conceptual entities. However,
> we encourage to use PROV also for provenance of conceptual entities
> and activities.
>
>
>> Furthermore, in activity(a,-,-,attrs) we said that the two time positions
>> are expandable, i.e.
>> there exists t1, t2, such that activity(a,t1,t2,attrs).  This didn't seem a
>> problem to say there exists t2, so why is it
>> a problem to inference a end event.
> In DM, an activity end time is optional. I have previously queried as
> to what 'optional' means, if it means it is implied or not specified.
> DM does not specify this, but here in Prov-Constraint  we are equiring
> that the time exists, and thus that the activity must end; and
> similarly that all entities must be invalidated.
>
>
> This is a stronger requirement that I think we need to agree on at a
> WG level. I can see the 'beauty' or 'consistency' argument to have
> invalidation match generation (and same for activity start/end), but
> we have previously agreed that PROV would not be describing things
> that will happen in the future, or things that would have happened if
> something was different.   (Thus we don't provide any details for
> plans or intended usages).
>
> In a normalized PROV instance, every entity and activity will end.
> This seems a bit odd, as perhaps those activities or entities will
> never end. Arguing that everything must end is a philosophical
> argument that I would rather we did not delve to deep into.
>
>
> Note that I am not insisting to remove requirement for invalidation
> and activity end time, I would agree on keeping them (perhaps with a
> note) if the WG votes that this is OK. (I would vote 0 for the sake of
> not blocking).
>
>

-- 
Professor Luc Moreau
Electronics and Computer Science   tel:   +44 23 8059 4487
University of Southampton          fax:   +44 23 8059 2865
Southampton SO17 1BJ               email: l.moreau@ecs.soton.ac.uk
United Kingdom                     http://www.ecs.soton.ac.uk/~lavm

Received on Wednesday, 8 August 2012 09:57:17 UTC