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Re: PROV-ISSUE-104 (time-class): How to relate start/end time to PE, use, generation, etc [Formal Model]

From: Paul Groth <p.t.groth@vu.nl>
Date: Fri, 14 Oct 2011 05:30:27 +0200
Message-ID: <3646D23B-FFB4-46A4-A3FE-D65E2374612D@vu.nl>
CC: "Groth, P.T." <p.t.groth@vu.nl>, Provenance Working Group WG <public-prov-wg@w3.org>
To: Stian Soiland-Reyes <soiland-reyes@cs.manchester.ac.uk>
Hi Stian
Formalizing time Is outside the scope. We shouldn't invent a time ontology.

All I'm asking for is time associated with different events as in the data model. 

If there are issues in the DM model bring them up.

But time annotations  are well defined in the DM also they are important so they should be included in prov-o.

I think there are two separate concerns between having obvious annotations and the inference that one can do with this annotations.

Paul

On Oct 13, 2011, at 23:48, Stian Soiland-Reyes <soiland-reyes@cs.manchester.ac.uk> wrote:

> On Wed, Sep 28, 2011 at 18:17, Paul Groth <p.t.groth@vu.nl> wrote:
>> Formalizing Time is outside the scope of the working group. We need to recognize that not everything will be able to be expressed otherwise we won't have interoperability.
> 
> and..
> 
> On Thu, Oct 13, 2011 at 17:49, Paul Groth <p.t.groth@vu.nl> wrote:
> 
>> I was wondering if examples of time could be put in the PROV-O Crime
>> Example. Like they are in PROV-DM.
>> 
>> It would be cool to see how we can put times against:
>> 
>> used,
>> wasGeneratedBy
>> Provenance Execution.
>> 
>> I can't see how to do it now. But maybe I'm just missing something?
> 
> As you raised this in a new thread, I continue here.
> 
> Note that since Issue-104 was raised PROV-DM have moved to a model of
> talking of more abstract 'events' - which I interpret to just be like
> milestones or markers, and prefer much more than the original
> reference to xsd:dateTime.
> 
> I think from the discussions so far we've concluded that we can't
> really say much about prov:Time (or prov:Event/prov:Instant, etc), as
> it can be a blurry landscape dealing with time. This is a similar
> approach that we have taken for prov:Recipe and prov:Location, they
> are just extension points to be specialised by applications. So we
> leave it as out of scope to define relations between prov:Time
> instances, etc, but we probably want to propose a "default" extension
> like owlTime for the basic uses of prov:Time where the finer details
> are not important.
> 
> 
> Even without an extension you can still do some useful inferencing if
> you use the same instances for things that happen at the same time.
> For instance:
> 
> 
> processExecution(pe1, tA, tB)
> used(pe1, e1, tC)
> wasGeneratedBy(e2, pe1, tA)
> wasGeneratedBy(e3, pe1, tA)
> wasGeneratedBy(e4, pe1, tB)
> 
> As you see, e2 and e3 was generated at the "same time", immediately at
> start of pe1, tA. (At this account's granularity level, of course). e4
> on the other hand is generated at tB, at the same time as pe1
> finishes.
> 
> pe1 used e1, but at time tC, which we don't know much about except it
> is somewhere between tA and tB (inclusive), and so we don't have
> enough information to determine that e2 could not have been affected
> by e1 - as perhaps tC == tA.   But is it fair to assume that tA != tB,
> e.g. that it has a duration > 0? pe1 could have been an "instantaneous
> event" (like a logical transition), such as those described in
> characterisation intervals of wasComplementOf.
> 
> Similar constraints about time is described for other relations in
> prov-dm, which (with enough thinking) gives a partial ordering of the
> events - however this order is never implicitly asserted. In the same
> way entities have a "characterisation interval" - but this interval
> can only be partially expressed through wasGeneratedBy time - there is
> no wasDestroyedBy relation to say when the entity ceased to be.
> 
> 
> I'll reply separately about the Crime example, as that has a more
> practical side to it.
> 
> -- 
> Stian Soiland-Reyes, myGrid team
> School of Computer Science
> The University of Manchester
Received on Friday, 14 October 2011 03:31:00 GMT

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