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[RDF-Concepts:109] What is the expressive power of RDF?

From: Graham Klyne <GK@ninebynine.org>
Date: Wed, 19 Feb 2003 16:05:36 +0000
Message-Id: <>
To: "Peter F. Patel-Schneider" <pfps@research.bell-labs.com>
Cc: www-rdf-comments@w3.org


With reference to your comment:

I accept a need for editorial revision, and have recorded it with id 
109-ExpressivePower [**].  The purpose of the rest of this message is to 
try to ensure that I properly understand your concerns.

[**] for my own tracking purposes:  when the scope of the issue is 
established, I'll ask Brian to allocate a WG tracking ID.

I think the problem can be described thus:
There is incorrect wording describing the expressive power of RDF.

A formal description would be:
"The expressive power of RDF is equivalent to the binary
existential-conjunctive subset of first order logic".

Any informal explanations should be consistent with this.

To further help me understand your concerns, can you clarify to me why you 
regard the following representations are not legitimate answers to the 
questions you raise:

1. How can
    be represented in RDF?

        <rdf:type rdf:resource="ex:TakingEvent" />
        <ex:taker rdf:resource="ex:John"/>
        <ex:taken rdf:resource="ex:Book"/>
        <ex:to    rdf:resource="ex:School"/>

2. How can
    be represented in RDF?

    <rdf:Description about="ex:John">
       <ex:loves rdf:parseType="resource">
             <ex:spouse rdf:resource="ex:John" />


At 10:26 AM 1/30/03 -0500, Peter F. Patel-Schneider wrote:

>RDF Concepts states
>         The expressive power of RDF corresponds to the
>         existential-conjunctive (EC) subset of first order logic [Sowa].
>How can
>         takes(John,book,school)
>be represented in RDF?
>How can
>         loves(John,spouse(John))
>be represented in RDF?
>How can the RDF and RDFS semantic conditions be represented in the
>existential-conjunctive subset of first order logic?

Graham Klyne
Received on Wednesday, 19 February 2003 11:28:31 UTC

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