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Re: PROV-ISSUE-157 (TLebo): wasInformedBy's non-transitivity

From: Daniel Garijo <dgarijo@delicias.dia.fi.upm.es>
Date: Mon, 5 Mar 2012 19:18:31 +0100
Message-ID: <CAExK0DeejjkzOMHFcRC58y7LxLtY52Wf3YOMZ_kGuEgWTEbQXQ@mail.gmail.com>
To: Provenance Working Group WG <public-prov-wg@w3.org>
Hi Tim,
The Current draft of the DM states that wasInformedBy is not transitive, so
I think we could close this issue. Alternatively, you can raise it against
the DM.

Thanks,
Daniel

2011/11/21 Provenance Working Group Issue Tracker <sysbot+tracker@w3.org>

>
> PROV-ISSUE-157 (TLebo): wasInformedBy's non-transitivity
>
> http://www.w3.org/2011/prov/track/issues/157
>
> Raised by: Timothy Lebo
> On product:
>
> The argument that wasInformedBy is not transitive is not clear and
> convincing.
>
> 1) Does the diagram correctly illustrate the assertions
> wasInformedBy(a2,a1) and wasInformedBy(a3,a2), and wasInformedBy(a3,a1)?
> There seems to be a lot of additional unstated assumptions that are
> embodied by the diagram beyond these three DM assertions.
>
> 2) It appears that the counterexample is using a "degenerate" situation,
> when the argument for non-transitivity can ALSO be made for activities
> following a more natural time flow (e.g., even when e2 is used AFTER e1 is
> generated). In this situation, we do not _know_ that the information in e2
> is related to the information in e1 _in any way_.
>
> 3) There is a "Note: This relation to be simplified using
> wasStartedBy/wasEndedBy.". Could someone point me to the expected changes
> here?
>
>
> Thanks,
> Tim
>
>
> Reference:
>
>
>
> http://dvcs.w3.org/hg/prov/raw-file/default/model/ProvenanceModel.html#record-OrderingOfActivities:
>
> """
> The relationship wasInformedBy is not transitive. Indeed, consider the
> records wasInformedBy(a2,a1) and wasInformedBy(a3,a2), the record
> wasInformedBy(a3,a1), may not necessarily hold, as illustrated by the
> following event line.
>
>            ------  a1
>             |
>             e1
>             |
>       -------  a2
>        |
>        e2
>        |
>     -----  a3
>
> The end in activity record identified by a3 precedes the start in activity
> record identified by a1, while interval for activity record a2 overlaps
> with each interval for a1 and a3, allowing information to flow (e1 and e2,
> respectively).
> """
>
>
>
>
Received on Monday, 5 March 2012 18:19:06 GMT

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