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Re: (Round 2) Proposed Extensions to OWL

From: Thomas B. Passin <tpassin@comcast.net>
Date: Sun, 6 Jul 2003 13:09:26 -0400
Message-ID: <002a01c343e1$5bd51660$6401a8c0@tbp1>
To: <www-rdf-interest@w3.org>
Cc: "Costello,Roger L." <costello@mitre.org>

[Roger L. Costello]
> I have incorporated Benja's and Tom's comments, and added a few of my
> own. Comments?  /Roger
>
> -----------------------------------------------------------------
> Conceptual Model:
>
> TangibleObject
>    physicalProperty
>       PhysicalProperty
>          measurement
>             Measurement
>                measurementValue
>                   MeasurementValue
>                      numericalValue
>                      unitSpecification
>                precision
>                source
>                ... (any other measurement metadata)
>
> -----------------------------------------------------------------

Almost there.  A general measurement might be characterized by something
more complex than a (value, units) pair.  That pair applies to a
lengthMeasurement but not to a Measurement in general.  So the general case
has to avoid having any details about the measurementValue, like this -

TangibleObject
   physicalProperty
      PhysicalProperty
         measurement
            Measurement
               measurementValue
                  MeasurementValue
               precision
               source
               ... (any other measurement metadata)



> Conceptual Model Applied to a TangibleObject which has a length:
>
> TangibleObject
>    length
>       Length
>          measurement
>             LengthMeasurement
>                value
>                   LengthValue
>                      number
>                      units
>                precision
>                source
>                ... (any other measurement metadata)
>

This is not quite synchronized with the general form above.  I think it
should be -

TangibleObject
   length
      Length
         measurement
            LengthMeasurement
               measurementValue  // instead of "value"
                  LengthValue
                     numericalValue  // instead of "number" (see below)
                     unitSpecification // instead of "units"
               precision
               source
               ... (any other measurement metadata)


> -----------------------------------------------------------------
> Conceptual Model Property Hierarchies:
>
>                         physicalProperty
>                                |
>               ---------------------------------
>               |                               |
>          lengthProperty                  areaProperty
>               |                               |
>    -------------------------            -------------
>    |       |      |        |            |           |
>  length  width  height  thickness     area         size
>
> and:
>         numericalValue     unitSpecification
>             |                     |
>          number                 units
>

So far I do not see value in specializing numericalValue to number, and
unitSpecification to units.  I think that any one numerical value will have
some unit spec, but the form of a unit spec will be the same for all values.
If that is correct, no specialization is needed.  In the interest of As
Simple As Possible, I would like to see them go away.  I favor the name
"numericalValue" over "number" for the more general case just because the
notion of "number" might tend to arise in other places, other ontologies,
and carries a lot of connotations tha we don;t want here.

> -----------------------------------------------------------------
> Conceptual Model Class Hierarchies:
>
>        PhysicalProperty            Measurement           Value
>              |                         |                   |
>       ----------------          LengthMeasurement    MeasurementValue
>       |              |                                     |
>    Length           Area                               LengthValue
>
> -----------------------------------------------------------------
> Concrete Example that Conforms to the Conceptual Model:
>

Subject  to resolution of my suggestions above ...

> <River rdf:ID="Yangtze">
>    <length>
>       <Length>
>          <measurement>
>             <Measurement>
>                 <value>
>                    <Value>
>                       <number>6300</number>
>                       <units rdf:resource="#LengthInKilometers"/>
>                    </Value>
>                </value>
>                <precision>(+/-)10km</precision>
>                <source>OGC</source>
>             </Measurement>
>          </measurement>
>       </Length>
>    </length>
> </River>
>

In practice, "source" would probably be a URI - that is, an RDF resource.
"precision" probably will need some modeling as well, but OK for now.  As it
stands, it is only human-readable and we will want it to RDF-interpretable
at some point.  Maybe something like this would be a start -

MeasurementPrecision
   precisionType
      StdError
          precisionValue
              NumericalValue
                  number // units are "%" by definition of StdError

Cheers,

Tom P
Received on Sunday, 6 July 2003 13:05:35 GMT

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