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Re: relations between activites

From: Stian Soiland-Reyes <soiland-reyes@cs.manchester.ac.uk>
Date: Fri, 6 Jul 2012 15:09:48 +0100
Message-ID: <CAPRnXtkEmfG4P_HbLJ-Lpi0H4_jCzyij=WA6m5Rv2jHsBF1sRA@mail.gmail.com>
To: Paul Groth <p.t.groth@vu.nl>
Cc: Satrajit Ghosh <satra@mit.edu>, "public-prov-comments@w3.org" <public-prov-comments@w3.org>
I would at least be very interested in defining activity composition
as part of PROV.

I think as Tim points out there are many existing ways to model
composition, but I don't think that means that PROV should ignore
composition of activities and entities - it would be important to
understand that for the outcome of the ex:Project there were many
ex:MRIScannings - if we leave these to custom attributes, then those
are separate islands in PROV.

We did get rid of wasStartedByActivity for simplicity. Perhaps for
wasInformedBy we can suggest some subtypes like prov:WasPartOf ?



On Fri, Jul 6, 2012 at 2:14 PM, Paul Groth <p.t.groth@vu.nl> wrote:
> Hi Satra,
>
> Thanks for the question. We actually have had several people ask a
> similar question. So I'm also curious what the group will answer :-)
>
> For wasFollowedBy, we actually have the relation wasInformedBy which
> you can use for activity ordering.
>
> I think we were reticent to start defining the composition of
> activities because that could lead down the path of defining an entire
> workflow or programming language, which is not in our charter or
> something we would want to do. I guess the answer was that we were
> worried about feature creep. Do we stop at just composition or would
> other constructs be necessary?
>
> thanks
> Paul
>
> On Fri, Jul 6, 2012 at 2:45 PM, Satrajit Ghosh <satra@mit.edu> wrote:
>> hello,
>>
>> i was discussing this with luc and based on his feedback thought it might be
>> useful to bring this up on the list.
>>
>> ----
>> question:
>> how do you encode that a certain activity "emailing a letter" happened
>> during another activity "a meeting"?
>>
>> for example we conduct research studies/projects.
>>
>> activity(p1, [prov:type='ex:Project'])
>> activity(p2, [prov:type='ex:MRIScanning', ex:session=1])
>> activity(p3, [prov:type='ex:MRIScanning', ex:session=2])
>>
>> how would i encode that this activity p2 and p3 were conducted during p1?
>> how would i encode p3 followed p2?
>>
>>
>> luc's response:
>> Regarding your question, there may be a few options:
>> you could add time information to your activities. This will help you
>> understand their ordering.
>>
>> Alternatively, if you want an explicit dependency in your graph, then p2 may
>> generate something
>> that starts p3, and/or is consumed by p3
>>
>> Finally, prov doesn't have relations between activities, to express their
>> nesting, etc. It's important
>> but we felt this is not specific to provenance, but to process executions.
>> ----
>>
>> it's the last point on this response that i was not completely sure about.
>> why "relations between activities" is "not specific to provenance, but to
>> process executions."
>>
>> in the above example, one could say:
>>
>> wasSubtaskOf(p2, p1)
>> wasSubtaskOf(p3, p1)
>> wasFollowedBy(p2, p3)
>>
>> any clarification as to why such relations would be outside the realm of
>> provenance would be much appreciated.
>>
>> cheers,
>>
>> satra
>



-- 
Stian Soiland-Reyes, myGrid team
School of Computer Science
The University of Manchester
Received on Friday, 6 July 2012 14:10:35 GMT

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