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Re: Logic and Using The Semantic Web Toolbox

From: Pierre-Antoine CHAMPIN <champin@bat710.univ-lyon1.fr>
Date: Sat, 02 Dec 2000 12:26:29 +0100
Message-ID: <3A28DC65.A4D72F43@bat710.univ-lyon1.fr>
To: Drew McDermott <drew.mcdermott@yale.edu>
CC: www-rdf-logic@w3.org
Drew McDermott wrote:
> Can anyone explain to me what the
> motivation is for (e.g.) forbidding nesting of expressions?
> Intuitively, a statement like
> (if (wins Bush election2000) (not (recounted election2000)))
> contains the subexpressions (wins Bush election2000) and (recounted
> election2000) without asserting them.

So you admit that (wins Bush election2000) does not have the same role when written alone, or as a nested expression.

In the language you use, every outer parenthesis-pair makes an assertion ; inner parenthesis-pairs do not.

In RDF, each arc of the graph makes an assertion. If you want to quote an arc without asserting it, you need to write/express it (in the graph) not as an arc. The chosen solution is reification.

But the graph is only an abstract syntax : it is neither intended to be a user-level language nor an implementation model !
So a more suited language would probably use parenthesis and interpret outer ones as assertions, and inner ones as reifications.
As for implementation models, they usually handle Statement objects, with their subject, predicate, object and ID all together.

Received on Saturday, 2 December 2000 07:39:30 UTC

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