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RE: A triple is not unique.

From: Bill dehOra <BdehOra@interx.com>
Date: Mon, 20 Nov 2000 10:30:33 -0000
Message-ID: <DD70D605CB99D411B13600508BDE6F2E081EDE@NTLONDON_01>
To: RDF-IG <www-rdf-interest@w3.org>
Cc: Dan Brickley <danbri@w3.org>, Seth Russell <seth@robustai.net>, "'McBride, Brian'" <bwm@hplb.hpl.hp.com>, "'Jonas Liljegren'" <jonas@rit.se>

> For the record, section 5, the formal model section of M&S states:
>   There is a set called Statements, each element of which is a triple
>   of the form {pred, sub, obj}
> That says that each Statement is a triple of the form (s,p,o).  A 
> triple in mathematics is uniquely determined by its three components.

I believe it would have been helpful of the spec to define Statement as a
Type (not rdf:type btw) which has as a denotation dStatement, the set of
things that are Statements, instead of just saying there is set whose
members are statements (that would follow from the Type definition).  We
could then have either an intensional definition in terms of a definition a
sentence triple is (a membership test), or an extensional definition in
terms of a catalogue of all the statements being in the world. The last is
unlikely, since it's an infinite number (countably infinite?).

From this we could sensibly ask the following:

1: Can we introduce Models (as used in various apis) as being members of the
powerset of dStatements? 
2: Is a Reified Statement a different Type than a Statement (does it have a
different intension?)
3: If 2 is true does Reified Statement have the same extension as Statement
(do they map to the same set?).

As an implementor, I can live with api Models being largely undefined. 2 and
3 are in my mind reasonably serious and need to be clarified. 

-Bill de hÓra
Received on Monday, 20 November 2000 05:32:34 UTC

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