W3C home > Mailing lists > Public > www-rdf-interest@w3.org > March 2002

Re: Using rdf reification to nest statements in N3 like contexts

From: Seth Russell <seth@robustai.net>
Date: Fri, 15 Mar 2002 12:28:29 -0800
Message-ID: <00bf01c1cc5f$f86ae900$657ba8c0@c1457248a.sttls1.wa.home.com>
To: "Graham Klyne" <GK@NineByNine.org>
Cc: "RDFIG" <www-rdf-interest@w3.org>
From: "Graham Klyne" <GK@NineByNine.org>

> Example:
>    A says { B says {C says D} . B a liar } .
> If I decide that what A says is true, I may enter the context of
> what A says and assert:
>    B says {C says D} . B a liar .
> If we have a syntactic construct for containment, as N3, then the contents
> of {...} can be treated opaquely as you suggest.  But when all this is
> encoded into a flat space of triples, some other mechanism is needed.  I
> proposing (multiple levels of) encoding as reification-quads.

Well I think that coding a triple as the RDF reification quad makes it
default to being opaque (not necessarialy true) in every context ... in
other words a reified statement is simply not asserted in any context.  If
we want the statement to be true in some context we will need to invent a
property that asserts in that context.  N3 seems to do that implicitly:   {B
a liar. {inner nested context}} means that inside the first {} 'B a liar' is
true, but what is in the {inner nested context} is not necessarily true.
When we project that back to simple triples we would need to explicitly
state the knowledge that 'B a liar' is true in the first outer context.

> If the inner  levels were not multiple encoded,
> we might end up concluding that in the
> context of what A says:
>    C says D
> is a truth, even though A also says that B is a liar.

See mentograph for comparison of the N3 quadTuples and RDF Triples for your
Note that the red triples are implicit in N3 but need to be stated
explicitly in RDF\XML.  The statement {C says D} although nested under the
context of what B believes, is still opaque to (not necessarialy true in)
that contex ... which is what we want.

Seth Russell
Received on Friday, 15 March 2002 15:32:23 UTC

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