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Re: Placing a comment on a relationship?!

From: Dan Brickley <danbri@w3.org>
Date: Thu, 20 May 2004 10:44:26 -0400
To: Adrian Walker <adrianw@snet.net>
Cc: Richard Lennox <listserve@richardlennox.net>, www-rdf-interest@w3.org
Message-ID: <20040520144426.GE7573@homer.w3.org>

* Adrian Walker <adrianw@snet.net> [2004-05-20 10:46-0400]
>    Richard --
>    Actually, I think you may have put your finger on a general problem.....
>    The general problem is, deductions that seem OK in RDF-ish notation are
>    sometimes OK in English, and sometimes absurd.
>    There's a nice example from John Sowa about this:  Clyde is an elephant,
>    elephant is a species, therefore Clyde is a species.  That's wrong in
>    English, but there are ways of writing it in RDF/OWL that look OK.

This is a classic example, stemming from two senses of 'isa'. Modern KR
systems including RDF/OWL distinguish them carefully. In RDF, we have 
'rdf:type' and 'rdfs:subClassOf' to represent two notions which 
might colloqially be described as 'is a' by an English speaker. In RDF, 
'type' relates an individual to a class; 'subClassOf' is a relation 
between classes.

Received on Thursday, 20 May 2004 10:44:29 UTC

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