From: Roger L. Costello <costello@mitre.org>

Date: Sat, 28 Jun 2003 06:31:11 -0400

Message-ID: <3EFD6E6F.D68398C4@mitre.org>

To: tpassin@comcast.net, www-rdf-interest@w3.org

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

Date: Sat, 28 Jun 2003 06:31:11 -0400

Message-ID: <3EFD6E6F.D68398C4@mitre.org>

To: tpassin@comcast.net, www-rdf-interest@w3.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 PReceived on Saturday, 28 June 2003 06:32:52 UTC

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