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

Hi

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.

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.

Luc

On 06/08/12 16:47, James Cheney wrote:
> I see no reason to require inferring invalidation and end events.  However, Luc was arguing for this internally.
>
> Luc's argument (IIRC) is that we know that everything will invalidate or end, and all we are doing here is saying that there must be some such event, and nothing more.  We don't infer a time or any attributes of the events.
>
> However, I think this is orthogonal to validity anyway; an instance that is valid with these inferences will (I think) be valid without, and vice versa, so I don't see a reason to keep if they are controversial.
>
> Luc?
>
> --James
>
>
> On Aug 6, 2012, at 4:26 PM, Provenance Working Group Issue Tracker wrote:
>
>> PROV-ISSUE-466 (must-entities-invalidate): Must all entities invalidate? [prov-dm-constraints]
>>
>> http://www.w3.org/2011/prov/track/issues/466
>>
>> Raised by: Stian Soiland-Reyes
>> On product: prov-dm-constraints
>>
>> Do we have WG consensus on that all entities must be invalidated,
>> and all activities must terminate? Seems to talk about the future,
>> rather than the past.
>>
>>>  From Stian's review http://lists.w3.org/Archives/Public/public-prov-wg/2012Aug/0021.html :
>>
>>> Inference 7 (entity-generation-invalidation-inference)
>>>  From an entity, we can infer that existence of generation and invalidation events.
>> This REQUIRES entities to become invalidated (at some point). It is
>> consistent with entities requiring generation, but it means I get
>> inferred strange wasInvalidatedBy for real life entities like:
>>
>> entity(math:pi)
>> entity(phys:universe)
>> entity(phys:vacuum)
>> entity(phys:energy)
>> entity(concept:existence)
>> entity(uk:2011census)
>> entity(uspolitics:resultOfPresidentialElection2012)
>>
>> When are these destroyed? By what? Is it certain that everything is
>> destroyed? What about things that are still existing at the time of
>> provenance being written, with this you are requiring them all to die
>> - I thought PROV only talked about the past. "We are all going to die"
>> - but you don't know when or how - so why should the PROV imply
>> provenance statements about the future?
>>
>>
>>
>>
>

-- 
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 Monday, 6 August 2012 16:16:20 UTC