W3C home > Mailing lists > Public > public-prov-wg@w3.org > November 2011

Re: PROV-ISSUE-145 (Tlebo): qualified identifiers may not work well with named graphs [Data Model]

From: Stian Soiland-Reyes <soiland-reyes@cs.manchester.ac.uk>
Date: Mon, 14 Nov 2011 00:13:30 +0000
Message-ID: <CAPRnXtmHMkPmC+4KLX8LXvUreCPNQnCOUMSwbRhy4DFGN_cO+Q@mail.gmail.com>
To: Graham Klyne <GK@ninebynine.org>
Cc: Luc Moreau <L.Moreau@ecs.soton.ac.uk>, public-prov-wg@w3.org
On Sun, Nov 13, 2011 at 11:50, Graham Klyne <GK@ninebynine.org> wrote:

> Generally, though, I think it is not a good idea to allow different accounts
> to use the same URI for different entities.  While accounts may contain
> statemenbts that are specific to the account, they should also provide for
> inferences about things (specifically, Entities) that hold outside the
> context of an account; e.g. entity1 derivedfrom entity2, if true, should be
> true independently of any account considered.

We can't really enforce different provenance asserters to not make
conflicting provenance assertions in different accounts - the
possibility of this is just a fact of life. We can advice against it,
but not prevent it.

Just like you can't tell if I am now writing a secret book explaining
about how Graham Klyne found the green Easter Bunny in the loft, you
can't know that someone else is not making a contradictory provenance
assertion about the URI which resource you are asserting something
about.

In RDF, if you are worried about this, you can counteract this by
minting your own fresh URIs (which can deliberately be contradicted
once they are known) or bnodes (which are unique per document/account,
can't as easily be crashed, but then again can't be referred to from
other provenance accounts of your own making).


An account is just that, it's one "view", "understanding" or "guess"
of how which things happened. Two different accounts might have a
different understanding of what exactly <http://example.com/me> means
- and therefore have a different kind of provenance trail. These
accounts might or might not be reconsilable, and certainly doing so
requires some isolation of the account assertions, using named graphs
or other scoping, like the container() and account() structures in
PROV-ASN.

A good hint of what kind of understanding the two accounts have of the
entity is by looking at their attributes, but ultimately there are
still no guarantees that they are truly talking about "the same
thing", just like you can't truly be sure who I meant if I casually
said something about "the prime minister".


-- 
Stian Soiland-Reyes, myGrid team
School of Computer Science
The University of Manchester
Received on Monday, 14 November 2011 00:14:27 UTC

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