W3C home > Mailing lists > Public > www-rdf-interest@w3.org > May 2003

Re: rdfs:class and rdfs:resource

From: Richard H. McCullough <rhm@cdepot.net>
Date: Wed, 7 May 2003 12:53:22 -0700
Message-ID: <001501c314d2$9c820440$bd7ba8c0@rhm8200>
To: "Jon Hanna" <jon@spin.ie>, "Www-Rdf-Interest" <www-rdf-interest@w3.org>

============ Dick McCullough knowledge := man do identify od existent done;
knowledge haspart proposition list;
----- Original Message ----- 
From: "Jon Hanna" <jon@spin.ie>
To: "Www-Rdf-Interest" <www-rdf-interest@w3.org>
Sent: Wednesday, May 07, 2003 11:07 AM
Subject: RE: rdfs:class and rdfs:resource

> > Jon
> > 1. You say
> >     <rdfs:Class> <rdf:type> <rdfs:Class> .
> > which is true.  But it also implies that
> >     <rdfs:Class> <owl:sameAs> <rdfs:Class> .
> > which is really more important.  In other words
> >     "every Class is identical to itself"
> > is more important and relevant than
> >     "every Class is a subClass of itself".
> I didn't say that every class is a subclass of class, but that rdfs:Class
> of type rdfs:Class.

You're right.  I skipped a step there.
> > 2. You did not consider whether
> >     <#jonsCar> <rdf:type> <rdfs:Class> .
> > Of course, it is not, because <#jonsCar> is not a Class.
> > That is what makes rdfs:Class different from all other classes.
> Yes. I considered this, but what I intended to be a brief mail was getting
> long-winded as it is, and left me with a choice of either re-writing as
> something more closely approaching an essay, or to excise a few bits.
> > There are two ways to resolve this "paradox".
> > (I agree with Francesco that it is a "paradox").
> I don't. It's a language problem (I'll see Francesco's Russell and raise
> a Wittgenstein :) Luckily this language problem is of a simple type, in
> the problem is in how we describe this to developers, rather than any
> inherent problem with language

I observe that developers (and end users) are having a hard time with
this "language problem".

> If it were truly paradoxical we would have problems explaining it to
> machines, and then we would be truly stuck.

I'm not convinced that machines understand this "language problem".

> Another way to think about this is with comparison to natural language:
> "thing" is a word. All words are things, including the word "word" and the
> word "thing". If we can categorise something as being a "word" then we can
> also categorise it as being a "thing". Hence "word" is a subclass of
> "thing". Further, all words are subclasses of "thing".
> "thing" is analogous to <rdfs:Resource> and "word" to <rdfs:Class>.

I agree.
But "thing" as a "word" and "thing" as an "existent"/"resource"
are two different contexts, two different ways of looking at "thing".
"thng" as a "word" is a symbol which refers to "thing" as an "existent".

A word is a symbol.  The referent of a word is a concept/Class.
The meaning of a concept/Class is something that actually exists
in reality.
Person (the word) refers to Person (the Class) which means the
group of real people like Jon Hanna and Dick McCullough.
Person (the word) is part of the vocabulary used for talking about
the real world.  We compose sentences from such words.
Person (the Class) is part of the Resource hierarchy used for
reasoning about the world.  We interpret the meaning of a
sentence using such Classes.
Received on Wednesday, 7 May 2003 15:55:35 UTC

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