# Re: (Round 2) Proposed Extensions to OWL

From: Roger L. Costello <costello@mitre.org>
Date: Sat, 28 Jun 2003 06:31:11 -0400
Message-ID: <3EFD6E6F.D68398C4@mitre.org>

CC: "Costello,Roger L." <costello@mitre.org>
```
Hi Folks,

Yes, I agree with Jeremy - I like the ideas that Tom has put forward.  I
also like the ideas that Jon put forward.  Very exciting ideas!

Some questions:

1. I am not sure that "transform" is the right word.  Both anonymous
resources are talking about length measures (in fact, the same length
measure).  But one *expresses* the length measure in inches, while the
other *expresses* the length measure in centimeters.  So, it's not a
"transform" but rather an *expression*, i.e.,

{resource
{type:length-measure}
{value:
expression-form:
{
type:length-in-inches}
number: 1
}
}
}

or perhaps:

{resource
{type:length-measure}
{value:
lexical-form:
{
type:length-in-inches}
number: 1
}
}
}

2. How would this be expressed in XML?  Would it be expressed like this:

<Length rdf:ID="length-in-inches">
<rdf:value>1.0</rdf:value>
</Length>

and

<Length rdf:ID="length-in-centimeters">
<rdf:value>2.54</rdf:value>
</Length>

Thus, both are expressing a Length.  The first is an instance of the
length in inches.  The second is an instance of the length in
centimeters.

Thoughts?  Great stuff!  /Roger

Tom Passin wrote:

> Here is what we know, it seems to me -
>
> 1) Both resources are length measures.
> 2) The value of a length measure can be expressed numerically in different
> units.
>
> (This is a scalar quantity.  A more complex quantity, like a vector or
> tensor, would have to be expressed as some structured value).
>
> We know a few other things, but they can be formulated in various ways.
> Here is one way.
>
> 3) The numerical value of a length measure may be obtained by applying an
> operator (or a transformation) to it.  That is, conceptually
> length-in-inches = L1 * M, where L1 is the operator for getting the length
> in inches, and M is the measure.
>
> 4) A measure may have any number of such operators or transforms, one for
> each different unit of measure.
>
> Here is a set of triples (minus namespaces) for your two resources that
> captures, I think, the essence of these points -
>
> {resource
>     {type:length-measure}
>     {value:
>         transform:
>             {
>                 type:length-in-inches}
>                 number: 1
>             }
>     }
> }
>
> {resource
>     {type:length-measure}
>     {value:
>         transform:
>             {
>                 type:length-in-cm}
>                 number: 2.54
>             }
>     }
> }
>
> I think that these are admirably simple, and I doubt that you can simplify
> them any more without losing their essence.
>
> The resource type can obviously be stated in OWL as part of an ontology, and
> so can the transform type.  If we had a standard way to make math statements
> with OWL, we could make an OWL statement that the two transforms (inch and
> cm) had some kind of "equivalentValueTo" relationship.
>
> This approach takes the matter of the relationship between length in cm and
> length in inches away from the individual resources and puts in onto the
> expression of the relationship between the transform types.  I think this is
> very appropriate.
>
> The upshot is that you need to come up with some convention for expressing
> the relationship between the transforms - or of testing for equivalence -
> and then everything else can be handled in OWL.
>
> Cheers,
>
> Tom P
```
Received on Saturday, 28 June 2003 06:32:52 UTC

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