Fwd: relations between activites

Hi,
   I hope I am following proper process... internal group discussion first (I may have missed earlier responses to this, as well)

my response to:
> wasSubtaskOf(p2, p1)
> wasSubtaskOf(p3, p1)
> wasFollowedBy(p2, p3)
The first relation describes elements of an invocation stack, the second is a special form of precedes() which we get by inference 
by stating start and end times of activities.
So the question is, whether the first is indeed a form of provenance. We seem to have accepted this in the case of the trigger in 
our wasStartedBy().

-Paolo

-------- Original Message --------
Subject: 	relations between activites
Resent-Date: 	Fri, 6 Jul 2012 12:46:38 +0000
Resent-From: 	<public-prov-comments@w3.org>
Date: 	Fri, 6 Jul 2012 08:45:44 -0400
From: 	Satrajit Ghosh <satra@mit.edu>
To: 	<public-prov-comments@w3.org>



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