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Re: (Round 2) Proposed Extensions to OWL

From: Frank Manola <fmanola@mitre.org>
Date: Fri, 27 Jun 2003 09:32:49 -0400
Message-ID: <3EFC4781.9020904@mitre.org>
To: "Roger L. Costello" <costello@mitre.org>
CC: www-rdf-interest@w3.org

Roger L. Costello wrote:

> Hi Folks,
> 
> Thanks for your comments yesterday.  We are making progress 
> (by discarding things that are not true).
> 
> Let's take a very close look at these anonymous resources again:
> 
> Resource #1:
> 
>        <rdf:Description>
>            <rdf:value>1.0</rdf:value>
>            <units>inch</units>
>        </rdf:Description>
> 
> Resource #2:
> 
>        <rdf:Description>
>            <rdf:value>2.54</rdf:value>
>            <units>centimeter</units>
>        </rdf:Description>
>       
> What do we know about these two anonymous resources?
> 
> 1. They do not represent the same resource.
> 
> 2. There is a relationship between
> 
>         concat(rdf:value, units) in resource #1, and
>         concat(rdf:value, units) in resource #2.
> 


I'm not sure what you mean by #2.  Certainly the relationship you're 
talking about isn't entirely expressed by the RDF.  Most of it is in the 
semantics you're reading into the "units" tag, the values of that 
element, and its appearance in the description of the same resource with 
an rdf:value.  There's nothing in the RDF that says anything about 
concatenating the values of the two properties, for one thing.  For 
another, imagine that the two resources had instead been:

 

Resource #1:

        <rdf:Description>
             <rdf:value>1.0</rdf:value>
             <vojut>jodi</vojut>
        </rdf:Description>

Resource #2:

        <rdf:Description>
            <rdf:value>2.54</rdf:value>
            <vojut>dfoujnfufs</vojut>
        </rdf:Description>

What would you conclude about the relationship between these two 
resources now?  (Note, for example, that there's nothing that says the 
value of the "vojut" element has anything to do with the value of the 
rdf:value element.)

Also, even if you accept the overall idea of the relationship you're 
talking about, "concatenation" (usually considered an operation on 
strings) isn't really involved.  If you want to express units and units 
conversions, things are a bit more complicated than this.

--Frank




-- 
Frank Manola                   The MITRE Corporation
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Received on Friday, 27 June 2003 09:09:29 GMT

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