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Re: PROV-ISSUE-242 (TLebo): generated twice? [prov-dm]

From: Stian Soiland-Reyes <soiland-reyes@cs.manchester.ac.uk>
Date: Tue, 7 Feb 2012 01:09:14 +0000
Message-ID: <CAPRnXtnVcAuG-08jr_vw3skMwL1nQ6hLgb20JJo0XN2Zsg1MsQ@mail.gmail.com>
To: Provenance Working Group <public-prov-wg@w3.org>
> Is the following valid?
> wasGeneratedBy(e,,2001-10-26T21:32:52)
> wasGeneratedBy(e,,2011-11-27T21:23:34)

You can't write time like that in ASN, they must be quoted literals or
kind-a-CURIEs. (And we should choose one of those to use for time in
ASN - it seems we already like to talk about t1,t2 etc, but elsewhere
claim it is XSD Date time. Given discussions in F2F I would suggest
the former.)

My interpretation of this is that 2011-11-27T21:23:34 and
2001-10-26T21:32:52 is the same event (the generation event). I don't
know what that means, perhaps that the generation is a very slow
thing, that the observer's clock has moved but the entity's clock has
not (say a frozen computer simulation), that the two times are the
same, or that the asserter is plain simply wrong.

And so I don't think we should say much about it.

It becomes of course much easier to narrow down the possibilities if
we separate times and events, as currently done in PROV-O with using
the (no longer time:) Instant resources - here you would just say:

:e prov:wasGeneratedAt :t1 .
:e prov:wasGeneratedAt :t2 .

:t1 prov:inXSDDateTime "2001-10-26T21:32:52"^^xsd:dateTime .
:t2 prov:inXSDDateTime "2011-11-27T21:23:34"^^xsd:dateTime .

(or equivalent long-version with prov:Generation and prov:hadTemporalValue)

prov:wasGeneratedAt is functional, because there is only one
generation event of an entity. Thus we know that :t1 == :t2 and can
limit our trouble-search there - in this case we could get an OWL
error because prov:inXSDDateTime is a functional datatype, or not,
depending on how strongly we choose to believe the owl:sameAs.

Stian Soiland-Reyes, myGrid team
School of Computer Science
The University of Manchester
Received on Tuesday, 7 February 2012 10:30:19 UTC

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