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Re: (Round 2) Proposed Extensions to OWL

From: Roger L. Costello <costello@mitre.org>
Date: Thu, 10 Jul 2003 09:06:44 -0400
Message-ID: <3F0D64E4.4FD1112B@mitre.org>
To: www-rdf-interest@w3.org
CC: "Thomas B. Passin" <tpassin@comcast.net>, "Costello,Roger L." <costello@mitre.org>, jon@spin.ie

A very good question Tom!  Your question has helped me to clarify things in my
mind.

Initially, my objective was to determine what extensions would be needed in OWL
to be able to assert that these two instances are equivalent:

<LengthValue>
          <numericalValue>3914</numericalValue>
          <unitSpecification rdf:resource="#Miles"/>
</LengthValue>

<LengthValue>
          <numericalValue>6300</numericalValue>
          <unitSpecification rdf:resource="#Kilometer"/>
</LengthValue>

I think that being able to assert that these two instances are equivalent is
very useful.  In fact, the creators of OWL also believe that asserting the
equivalence of instances is important.  That's why owl:sameIndividualAs was
provided.

> I think I have worked that out in a satisfactory way for specific instances.

Now that I am a bit clearer on some things I will go back to your latest
postings and try to summarize your solution.

Recently, I have come to realize that it would also be very useful to simply
provide in an ontology statements of units and how they relate.  Then given such
statements, applications could determine at run-time if two instances are
equivalent.  I believe that this capability would fall into this category:

> 2) Provide a means by which a processor could infer the equivalence of two
> values (with their units included, of course)

I am excited by the first category you mention:

> 1) Make a statement of such equivalence without having to create a specific
> instance of a transformation for each case.

This would be the ultimate!  Do you have ideas on achieving this?  /Roger


"Thomas B. Passin" wrote:

> [Roger L. Costello]
>
> > Tom, I am still fuzzy about your proposal.  I need to see a concrete
> example.
>
> Roger, I think we are tackling two different problems, although they are
> closely related.  I was working out how one could make an RDF statement that
> two LengthMeasurementValues are actually equivalent because one is the
> transform of the other.  I think I have worked that out in a satisfactory
> way for specific instances.
>
> There are several other things one might like to do, and I think you may be
> trying to combine them without realizing it -
>
> 1) Make a statement of such equivalence without having to create a specific
> instance of a transformation for each case.
>
> 2) Provide a means by which a processor could infer the equivalence of two
> values (with their units included, of course)
>
> 3) Provide instructions to some processor so that if queried, it could
> return sensible answers, e.g.,
>    a) Yes, the two are equivalent or No, they are not.
>    b) A length of 1 Mile is equivalent to a length of 1.62 Kilometers with a
> precision of '...'.
>
> Remember, we cannot instruct a pure RDF processor to "do" anything.  It
> takes statements and organizes them.  It may try to infer new statements and
> add them to the data store.  So 3) is not really in the realm of RDF,
> although presumably we would want to use RDF to specify the transform to
> use.
>
> So which one of these is most on your mind? They are different tasks.
>
> Cheers,
>
> Tom P
Received on Thursday, 10 July 2003 09:06:57 GMT

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