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Re: some GRAPHS strawpolls for today (agenda?)

From: William Waites <wwaites@tardis.ed.ac.uk>
Date: Sat, 28 Apr 2012 17:21:01 +0100 (BST)
Message-Id: <20120428.172101.536854495.wwaites@tardis.ed.ac.uk>
To: sandro@w3.org
Cc: public-rdf-wg@w3.org
On Wed, 25 Apr 2012 10:08:55 -0400, Sandro Hawke <sandro@w3.org> said:

    sandro> 1. The default graph is asserted

    sandro>   "{<a> <b> <c>}" entails turtle("<a> <b> <c>")

If this means "storing something in the the default graph in a
triplestore or a trig document is the same as writing it down using
turtle" then I agree. If this means "asserted as some sort of
context-less eternal truth" I disagree.

    sandro> 2. Named graphs are not asserted

    sandro>   "<u> {<a> <b> <c>}" does not entail turtle("<a> <b>
    sandro> <c>")

Agree. A statement taken out of context is not the same as one
in-context.

    sandro> 3. Named graphs are opaque

    sandro>   "<u> {<a> <b> <c>}" does not entail "<u> {<a> <b> _:x}"

Why should this be so? I think it is valid (though not necessarily
useful) to make this inference.

    sandro> 4. Graph labels denote just like in RDF

    sandro>   "{<u1> owl:sameAs <u2>} <u1> {<a> <b> <c>}" owl-entails
    sandro> "<u2> {<a> <b> <c>}"

Yes.

    sandro> 5. Blank nodes labels have file scope

I think blank nodes have enclosing-graph scope. Just like
let-expressions in LISP.

    sandro> 6. In trig, @union can be used in place of the default
    sandro> graph

    sandro>    "@union <u> {<a> <b> <c>}" entails turtle "<a> <b> <c>"

Not necessarily. I fail to see why we need a special union operator
and why we don't just write,

    g3 unionOf g1,g2.

or even,

    _:g3 unionOf g1,g2

which means that g3 has all the statements that are in g1 and g2.

    sandro> 7. Datasets only say which triples are known to be in a
    sandro> named graph, not which triples are *not* in that named
    sandro> graph.

I think we still have the open-world assumption when the data is not
being observed and the world closes when it is being transmitted or a
query evaluated for the purposes of that transmission or query
evaluation.

Cheers,
-w
--
	    William Waites MBCS <wwaites@tardis.ed.ac.uk>
 Visiting Researcher, Laboratory for Foundations of Computer Science
	    School of Informatics, University of Edinburgh

Received on Saturday, 28 April 2012 16:21:10 UTC

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