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Re: (Round 2) Proposed Extensions to OWL

From: Benja Fallenstein <b.fallenstein@gmx.de>
Date: Thu, 03 Jul 2003 19:17:58 +0200
Message-ID: <3F046546.5090608@gmx.de>
To: "Roger L. Costello" <costello@mitre.org>
CC: www-rdf-interest@w3.org, jon@spin.ie, tpassin@comcast.net

Roger L. Costello wrote:
> Document #1 shows the length in kilometers:
> 
> <River rdf:ID="Yangtze">
>     <length>
>         <Length>
>             <measurement>
>                 <LengthInKilometers>
>                     <number>6300</number>
>                 </LengthInKilometers>
>             </measurement>
>         </Length>
>     </length>
> </River>
> 
> Document #2 shows the length in miles:
> 
> <River rdf:ID="Yangtze">
>     <length>
>         <Length>
>             <measurement>
>                 <LengthInMiles>
>                     <number>3914</number>
>                 </LengthInMiles>
>             </measurement>
>         </Length>
>     </length>
> </River>
...
> Question: what is the role of OWL with respect to these models?  Should
> an OWL document be responsible for stating the conversion factor among
> models?  

If we ignore (for the purposes of brainstorming) the problem of 
precision, we can state using OWL that--

- the object of 'length' is a 'Length' with cardinality 1
- the subject of 'measurement' is a 'Length' with cardinality 1

Let's say we know the above, your two documents, and a third document:

<Distance>
     <from rdf:resource="#myHome"/>
     <to   rdf:resource="#yourHome"/>
     <length>
         <Length>
             <measurement>
                 <LengthInMiles>
                     <number>3914</number>
                 </LengthInMiles>
             </measurement>
         </Length>
     </length>
</Distance>

Then we can conclude--

- The two Length resources of the Yangtze river are the same 
(sameIndividualAs), because the object of the 'length' property has 
cardinality 1.

Hmm... If we somehow could also state that two LengthInMiles with the 
same 'number' are the same resource, then (and only then) we could go on 
to conclude that--

- The two Length resources measured in miles are the same resource, 
because they have the same measurements (subject has cardinality 1); and 
therefore,

- all the three Length objects are the same resource; and therefore,

- the distance from my home to your home is 6300 kilometers.

However (as I realized while typing) this only works if we can state 
that two <LengthInMiles number="xxx"/> are the same resource if xxx is 
the same. Argl!

It *would* work-- even if that's less attractive-- if we did this:

<River rdf:ID="Yangtze">
     <length>
         <Length len:lengthInMiles="3914"/>
     </length>
</River>

Then we could state that both lengthInMiles and lengthInKilometers are 
1:1 properties, and thus conclude equivalence by example as above.

- Benja
Received on Thursday, 3 July 2003 13:19:13 GMT

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