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about EntityInRole and assumedBy

From: Luc Moreau <L.Moreau@ecs.soton.ac.uk>
Date: Wed, 26 Oct 2011 16:22:27 +0100
Message-ID: <EMEW3|f8318b2069147df66eea3a5435f1b06cn9PGMW08L.Moreau|ecs.soton.ac.uk|4EA825B3.6070104@ecs.soton.ac.uk>
To: Provenance Working Group WG <public-prov-wg@w3.org>

Dear all,

I would like to reiterate again my concern about the mismatch between
prov-dm and prov-o. I think the two notions the documents diverge on are
entityInRole (a subclass of Entity) and assumedBy (which in essence is
a kind of specialization of wasComplementOf).

They are introduced in the ontology to be able to express time and 
qualifiers
(including role) for use and generation.

It is suggested by JamesC and Graham that we write examples to 
understand the
differences, it is a very good point that I support.

I would like to explain the problem I have with the EntityInRole solution.

Let's take the case of a used relation (ideas apply similarly to 
generation).
Let's imagine there is no qualifier/time information.
We want to be simple, and express a property, as prov-o does:

Encoding1:
   pe prov:used e1

If we suddently have time information or role, according to prov-o, we 
would have to write:

Encoding2:

  pe prov:used e1X
  e1X  prov:assumedBy e1
  e1X  prov:assumedAt t1
  e1X  prov:assumedRole r

My problems are the following:

- Encoding2 is not an extension of encoding1: it  does not just add new 
edges,
   it removes some.
   But according to the data model, we just have added extra information.

- why should I change my "modelling of what happens in the world",
   encoding2 has got two entities when encoding1 has got only one.

- I believe it would be reasonable to write
     e1X wasComplementOf e1  (since it looks like e1X has attributes 
that e1 doesn't have,
     and have a common time interval).

   What's the difference between e1X WasComplementOf e1 and e1X 
assumedBy e1?
    wasComplementOf is hard enough, why do we have to have something so 
similar to it,
    but restricted to entityInRole?

- Imagine the scenario is more complex and e1 is used by a second 
process in another
   role, at time t2>t1 so we may have another entity e2X.
   It would also be reasonable to write e2X wasDerivedFrom e1X because 
e2X follows e1X.
   But this wouldn't be possible in prov-dm, unless we explictly 
introduce e1X and e2X.


Cheers,
Luc


-- 
Professor Luc Moreau
Electronics and Computer Science   tel:   +44 23 8059 4487
University of Southampton          fax:   +44 23 8059 2865
Southampton SO17 1BJ               email: l.moreau@ecs.soton.ac.uk
United Kingdom                     http://www.ecs.soton.ac.uk/~lavm
Received on Wednesday, 26 October 2011 15:23:09 GMT

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