relations between activites

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