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Re: [provo] Re: Difference between wasInformedBy and wasStartedByActivity (ttl examples)

From: Stian Soiland-Reyes <soiland-reyes@cs.manchester.ac.uk>
Date: Thu, 3 May 2012 12:18:31 +0100
Message-ID: <CAPRnXt=iryZhUAKoXZ5i5GFCVvTVos8gU19_oL+LTO+qVDwjKQ@mail.gmail.com>
To: Khalid Belhajjame <Khalid.Belhajjame@cs.man.ac.uk>
Cc: Jun Zhao <jun.zhao@zoo.ox.ac.uk>, Timothy Lebo <lebot@rpi.edu>, W3C provenance WG <public-prov-wg@w3.org>
I think in general your considerations are right.

On Thu, May 3, 2012 at 11:23 AM, Khalid Belhajjame
<Khalid.Belhajjame@cs.man.ac.uk> wrote:

> :letterRespection a prov:Activity .
> :accidentNotification a prov:Entity .
> :accidentNotification prov:wasGeneratedBy :letterReception .
> :insurranceClaim a prov:Activity ;
>     prov:wasStartedBy :accidentNotification ;
>     prov:wasStartedByActivity :letterReception .

I'm not sure if that would be a good example. It would simply be
restating the same in two different ways, so it would be wrong
guidance on when to use prov:wasStartedByActivity .

In http://dvcs.w3.org/hg/prov/raw-file/default/examples/eg-24-prov-o-html-examples/rdf/create/rdf/property_wasStartedByActivity.ttl
I have changed the fuel-filling example:

    a prov:Activity;
    prov:startedAtTime        "2012-04-24T18:21:00Z"^^xsd:dateTime ;
    prov:endedAtTime          "2012-04-24T18:23:10Z"^^xsd:dateTime ;
    prov:wasAttributedTo      :driver ;
    prov:wasStartedByActivity :observing-low-fuel .

    a prov:Activity;
    prov:wasAttributedTo      :driver ;
    prov:startedAtTime        "2012-04-24T17:45:00Z"^^xsd:dateTime .

:driver a prov:Person, prov:Agent .

So here, the entity is some kind of warning light, or it could be
looking at the fuel meter, or perhaps it was a very old car that
starts making 'coughing' sounds when there's low fuel. We don't know,
and so we have not asserted that messaging entity, and we did not use
prov:wasStartedBy. If you later see prov:wasStartedBy, you can say
"Ah, that's the one".

I believe that if you use prov:wasStartedBy, then also saying
prov:wasStartedByActivity is just restating the same in a blurrier
manner according to the inference rules of PROV-constraints - like
stating prov:tracedTo after stating a prov:wasDerivedFrom.

This could still be appropriate for cases where you want to attach
some properties to the wasStartedbyActivity relation, or where the
activity-to-activity relation is much more important than the entity
(I started investigating the accident, but it does not matter if I was
told about the case by telephone or email), and so I agree on your
proposed change to DM - the entity does not *need* to be unspecified.

Stian Soiland-Reyes, myGrid team
School of Computer Science
The University of Manchester
Received on Thursday, 3 May 2012 11:19:21 UTC

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