Re: Activity composition

May I ask what /is/ activity composition? i.e. what is the semantics of
   :a2 a prov:Activity; dc:partOf :a1

(the use of dc:partOf seems to confirm that prov does not include such concept).

Also, I think what Davide has in mind with
  " two separate graphs stating that each of the two activities generated the entity"
is a form of "bundling", or separate accounts, so the statement

:e1 a prov:Entity; prov:wasGeneratedBy :a1, :a2.

would not hold within a single account, and thus the generation-uniqueness rule does not apply?

-Paolo




On 5/9/12 11:06 PM, Stephan Zednik wrote:
> Perhaps wasGeneratedBy should not be functional?
>
> I think supporting activity composition will be heavily requested by the provenance community.  I know projects at RPI/HAO  that I 
> am a part of and provenance projects at CSIRO have recognized it as an important (potentially critical) aspect in generating 
> provenance presentations/visualizations for end users.
>
> Perhaps if a :a2 generated an entity :e2 that was a specialization of :e1?
>
> We ~should~ be able to record provenance at different, and logically connected, levels of abstraction, and activity composition 
> seems a natural component for doing so.
>
> --Stephan
>
> On May 9, 2012, at 3:56 PM, Jim McCusker wrote:
>
>> There are some problems here with composition though, specifically when you try to say something like this:
>>
>> :a1 a prov:Activity.
>> :a2 a prov:Activity; dc:partOf :a1.
>>
>> :e1 a prov:Entity; prov:wasGeneratedBy :a1, :a2.
>>
>> Basically, since :a2 is part of :a1, and :a2 served as a "final activity" (there aren't any further activities that used :e1), 
>> :e1, by virtue of being generated by :a2 was also generated by :a1. But since wasGeneratedBy is functional, we cannot assert that 
>> without :a1 and :a2 becoming identical (sameAs).
>>
>> Jim
>>
>> On Wed, May 9, 2012 at 5:47 PM, Paolo Ncl <Paolo.Missier@ncl.ac.uk <mailto:Paolo.Missier@ncl.ac.uk>> wrote:
>>
>>     Davide
>>
>>     I guess it depends on how you define "part of" in this setting. You can specify that an activity has started another, which
>>     makes, informally, the former a "parent" of the latter. You can use this to model forking, for example. This is about the
>>     observed behavior of a process and is within scope. But there is no way to express structural containment, or composition,
>>     because describing process models and structure (for instance, the structure of a program, a workflow, a script etc.) is not
>>     within the PROV scope.
>>     I hope others in the group concur with this interpretation
>>
>>     Regards,
>>
>>     P.Missier - paolo.missier@ncl.ac.uk <mailto:paolo.missier@ncl.ac.uk>
>>
>>     On 7 May 2012, at 21:44, Davide Ceolin <davide.ceolin@gmail.com <mailto:davide.ceolin@gmail.com>> wrote:
>>
>>     > Hello,
>>     >
>>     > I am a PhD student of the VU University Amsterdam, and I would have a question about the composition of activities in PROV.
>>     I noticed that it is not possible to explicitly state that an activity is actually part of another one.
>>     >
>>     > Suppose that a given entity is the result of an activity and, in turn, this activity is part of a larger one.
>>     >
>>     > I can represent this scenario with two separate graphs stating that each of the two activities generated the entity, and
>>     from them (and their execution times, etc.) I may infer that one is part of the other one, but I can't explicitly state that.
>>     >
>>     > Is there a specific reason for such a limitation?
>>     >
>>     > Thanks,
>>     >
>>     > Davide
>>     >
>>     > Davide Ceolin MSc.
>>     > PhD student
>>     > The Network Institute
>>     > VU University Amsterdam
>>     > d.ceolin@vu.nl <mailto:d.ceolin@vu.nl>
>>     > http://www.few.vu.nl/~dceolin/ <http://www.few.vu.nl/%7Edceolin/>
>>     >
>>     >
>>     >
>>
>>
>>
>>
>> -- 
>> Jim McCusker
>> Programmer Analyst
>> Krauthammer Lab, Pathology Informatics
>> Yale School of Medicine
>> james.mccusker@yale.edu <mailto:james.mccusker@yale.edu> | (203) 785-6330
>> http://krauthammerlab.med.yale.edu <http://krauthammerlab.med.yale.edu/>
>>
>> PhD Student
>> Tetherless World Constellation
>> Rensselaer Polytechnic Institute
>> mccusj@cs.rpi.edu <mailto:mccusj@cs.rpi.edu>
>> http://tw.rpi.edu <http://tw.rpi.edu/>
>


-- 
-----------  ~oo~  --------------
Paolo Missier - Paolo.Missier@newcastle.ac.uk, pmissier@acm.org
School of Computing Science, Newcastle University,  UK
http://www.cs.ncl.ac.uk/people/Paolo.Missier