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Re: PROV-ISSUE-467 (activity-start-req-trigger): Do activity start/end always require trigger? [prov-dm-constraints]

From: James Cheney <jcheney@inf.ed.ac.uk>
Date: Mon, 6 Aug 2012 16:53:18 +0100
Message-Id: <17895663-F524-4B56-915D-53FDEA7490CF@inf.ed.ac.uk>
To: Provenance Working Group <public-prov-wg@w3.org>
Since you don't give an indication of what would resolve the issue, I'm not sure if this is a problem with PROV-DM, or with PROV-CONSTRAINTS?  

If the latter, would making the trigger parameters non-expandable (so that you can write "-" for a missing trigger) fix the problem?  If so, I propose we do so.  (This will also require being careful about these arguments later, as for derivation and association.)

Are you also arguing for removing the wasEndedBy part of the conclusion?  If so, any objections?

--James

On Aug 6, 2012, at 4:28 PM, Provenance Working Group Issue Tracker wrote:

> PROV-ISSUE-467 (activity-start-req-trigger): Do activity start/end always require trigger? [prov-dm-constraints]
> 
> http://www.w3.org/2011/prov/track/issues/467
> 
> Raised by: Stian Soiland-Reyes
> On product: prov-dm-constraints
> 
> Do we have WG consensus on activity start/end requiring triggers?
> Can an activity terminate itself without a trigger? Start
> instantaneously?
> 
>> From Stian's review http://lists.w3.org/Archives/Public/public-prov-wg/2012Aug/0021.html :
> 
> 
> 
>> IF activity(a,t1,t2,_attrs) THEN there exist _id1, _e1, _id2, and _e2 such that wasStartedBy(_id1;a,_e1,_a1,t1,[]) and wasEndedBy(_id2;a,_e2,_a2,t2,[]).
> 
> So it is impossible for an activity to start or end without a trigger?
> I am not so sure about this.. this creates phantom triggers, not too
> dissimilar to our previous phantom agents, in particular for a
> self-terminating process this can become a bit odd, "I'll tell my self
> to stop now!"
> 
> All activities must end? Same argument as for inference 7 applies.
> 
> 
> 
> 
> 
> 
> 


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Received on Monday, 6 August 2012 15:53:40 UTC

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