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RE: Logic and Using The Semantic Web Toolbox

From: McBride, Brian <bwm@hplb.hpl.hp.com>
Date: Wed, 6 Dec 2000 07:41:54 -0000
Message-ID: <5E13A1874524D411A876006008CD059F239547@0-mail-1.hpl.hp.com>
To: www-rdf-logic@w3.org
>    Pierre-Antoine CHAMPIN wrote:
> 
>       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.
> 
> I realize this is the model.  I don't understand the rationale for it,
> or why the issue has already been decided.  (I also don't understand
> why reification solves the problem; if it's supposed to be beyond my
> control whether all subgraphs of G are asserted whenever I assert G,
> why isn't it beyond my control to prevent the assertion of expressions
> that are named without being uttered?)

It appears, to me at least, to be worse than that.  Whilst the RDF M&S
spec talks about graphs and statements being members or not of a graph,
its formal model defines no concept of a graph, and thus has no way
of distinguishing whether a statement is a member of a graph or not.

Graham's context proposal was aimed at addressing this, as my suggestion
of formalizaing the concept of model (viz graph).

RDF is just a data model.  It has no way to 'assert' anything on its
own.  Either it must be revisited, or mechanisms for that are the province
of the logic layer.

Brian McBride
HPLabs.
Received on Wednesday, 6 December 2000 02:42:00 GMT

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