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Re: about EntityInRole and assumedBy

From: Daniel Garijo <dgarijo@delicias.dia.fi.upm.es>
Date: Fri, 28 Oct 2011 13:21:55 +0200
Message-ID: <CAExK0Df3_MRnaoFSsnn1fBSisfot0izCLZDXLSHBwZNjbU0umg@mail.gmail.com>
To: James Cheney <jcheney@inf.ed.ac.uk>
Cc: Khalid Belhajjame <Khalid.Belhajjame@cs.man.ac.uk>, Luc Moreau <L.Moreau@ecs.soton.ac.uk>, Provenance Working Group WG <public-prov-wg@w3.org>
Hi James,

When we started this small task force, we looked for alternatives to solve
this issue. We had 3 possible approcahes:

   1. The OPMO approach modelling edges as n-ary relationships.
   2. Satya's approach with EntityInRole.
   3. The OPMV approach especializing roles as subproperties of the "use"
   relationship.

Approach 3) was dropped because despite it is very simple and direct, it is
not possible to add time and location to the edges
(all the properties are binary).
Approach 1) covered the functionality in my opinion (although Satya may have
some objections against it), but we decided to go
for approach 2) which now has brought some problems.

Unfortunately I'm not aware of other ways to model n-ary relationships. If
someone comes up with a new approach on monday,
I'll be happy to discuss it.

Best,
Daniel

2011/10/28 James Cheney <jcheney@inf.ed.ac.uk>

> Just to clarify, I believe the alternative I'd suggested (which Khalid
> gives in proper Turtle/RDF notation below) is similar to that in OPM-O,
> which had Used as a class rather than a property.  I'm not claiming to have
> come up with this on my own, I'm sure I had seen the OPM-O treatment and
> inadvertently reinvented it.
>
> My main question is, is that approach more palatable than the EntityInRole
> approach?  If not, what alternative would be a better fit for the current
> PROV-DM?
>
> --James
>
> On Oct 26, 2011, at 7:42 PM, Khalid Belhajjame wrote:
>
> >
> > Hi Luc, all,
> >
> > We are aware of the problems that EntityInRole is introducing. Following
> your comments in last emails, we are contemplating a new alternative, that
> was suggested by James, which seems to be inline with the PROV-DM. Not all
> members of the ontology group have expressed their opinion yet, though.
> >
> > The idea is to have two owl classes Usage and Generation. These two
> classes are connected to Entity and Process Execution (using object
> properties), and qualifiers, such as role, can be defined as object
> properties of Usage and Generation. For example, Usage can be defined as:
> >
> > prov:Usage a owl:Class.
> >
> > prov:hasEntity
> >    a rdf:Property ;
> >    rdfs:domain prov:Usage ;
> >    rdfs:range prov:Entity .
> >
> > prov:hasProcessExecution
> >    a rdf:Property ;
> >    rdfs:domain prov:Usage ;
> >    rdfs:range prov:ProcessExecution .
> >
> > prov:hasRole
> >    a rdf:Property ;
> >    rdfs:domain prov:Usage ;
> >    rdfs:range prov:Role .
> > ...
> >
> > Additionally, to be closer to the model, we can define shortcuts
> properties: used and wasGeneratedBy as object properties that connect
> process execution and entities. For example,
> >
> > prov:used
> >    a rdf:Property ;
> >    rdfs:domain prov:ProcessExecution ;
> >    rdfs:range prov:Entity .
> >
> > There is at least one issue that we are aware of using this design, but
> IMO, it is better.
> >
> > khalid
> >
> > On 26/10/2011 16:22, Luc Moreau wrote:
> >>
> >> 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
> >>
> >>
> >
> >
> >
>
>
> --
> The University of Edinburgh is a charitable body, registered in
> Scotland, with registration number SC005336.
>
>
>
Received on Friday, 28 October 2011 11:22:24 GMT

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