W3C home > Mailing lists > Public > www-rdf-comments@w3.org > January to March 2003

[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: <5.1.0.14.2.20030218122804.03bfe1e0@127.0.0.1>
To: "Peter F. Patel-Schneider" <pfps@research.bell-labs.com>
Cc: www-rdf-comments@w3.org

Peter,

With reference to your comment:
   http://lists.w3.org/Archives/Public/www-rdf-comments/2003JanMar/0154.html

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
    takes(John,book,school)
    be represented in RDF?

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


2. How can
    loves(John,spouse(John))
    be represented in RDF?

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

#g
--

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
<GK@NineByNine.org>
Received on Wednesday, 19 February 2003 11:28:31 GMT

This archive was generated by hypermail 2.2.0+W3C-0.50 : Friday, 21 September 2012 14:16:31 GMT