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Re: Weights and Measures

From: Graham Klyne <GK@ninebynine.org>
Date: Tue, 13 Mar 2001 17:29:17 +0000
Message-Id: <5.0.2.1.2.20010313172444.0393b450@joy.songbird.com>
To: "Jeremy Carroll" <jjc@hplb.hpl.hp.com>
Cc: <www-rdf-interest@w3.org>
TimBL discusses similar issues in 
http://www.w3.org/DesignIssues/InterpretationProperties.html (which I 
notice has been updated relatively recently).

#g
--

At 03:44 PM 3/13/01 +0000, Jeremy Carroll wrote:
>Lee Jonas wrote:
> > -----Original Message-----
> > Sent: 12 March 2001 16:38
> > To: www-rdf-interest@w3.org
> > Subject: Re: Again: Anonymous Resources
>[..omit..]
> > However, consider the example the RDF M&S spec gives for qualified values.
> > It describes measurements as the coupling of the unit of measurement with
> > the quantity via an intermediary resource, e.g. 8-Kg, 128-Mb,
> > 2-meters, etc.
>
>I am new to RDF, (I've just started working with Brian McBride); I had to go
>and look at the spec to understand this, and I was surprised.
>
> >From the spec http://www.w3.org/TR/REC-rdf-syntax/ :
>
>----------------
>A common use of this higher-arity capability is when dealing with units of
>measure. A person's weight is not just a number such as "200", it also
>includes the unit of measure used. In this case we might be using either
>pounds or kilograms. We could use a relationship with an additional arc to
>record the fact that John Smith is a rather strapping gentleman:
>
><RDF
>   xmlns="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
>   xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
>   xmlns:n="http://www.nist.gov/units/">
>   <Description about="John_Smith">
>     <n:weight rdf:parseType="Resource">
>       <rdf:value>200</rdf:value>
>       <n:units rdf:resource="http://www.nist.gov/units/Pounds"/>
>     </n:weight>
>   </Description>
></RDF>
>-------------------
>
>This is counterintuitive in that it (incorrectly) gives only one (numeric)
>value for John Smith's weight.
>It is natural, at least to me, to want to augment the above graph with
>John's weight in Kilo's. This is a further attribute of John's weight,
>rather than an additional description of John.
>
>Unfortunately, the following is unintelligible:
>
><RDF
>   xmlns="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
>   xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
>   xmlns:n="http://www.nist.gov/units/">
>   <Description about="John_Smith">
>     <n:weight rdf:parseType="Resource">
>       <rdf:value>200</rdf:value>
>       <n:units rdf:resource="http://www.nist.gov/units/Pounds"/>
>       <rdf:value>91</rdf:value>
>       <n:units rdf:resource="http://www.nist.gov/units/Kilograms"/>
>     </n:weight>
>   </Description>
></RDF>
>
>And, this one, seems to suggest John has two different weights:
><RDF
>   xmlns="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
>   xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
>   xmlns:n="http://www.nist.gov/units/">
>   <Description about="John_Smith">
>     <n:weight rdf:parseType="Resource">
>       <rdf:value>200</rdf:value>
>       <n:units rdf:resource="http://www.nist.gov/units/Pounds"/>
>     </n:weight>
>     <n:weight rdf:parseType="Resource">
>       <rdf:value>91</rdf:value>
>       <n:units rdf:resource="http://www.nist.gov/units/Kilograms"/>
>     </n:weight>
>   </Description>
></RDF>
>
>I would prefer to see the weight with two properties, one the weight in
>Kilo's another the weight in pounds. Both of these properties could be
>subproperties of rdf:value.
>This might suggest:
><RDF
>   xmlns="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
>   xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
>   xmlns:n="http://www.nist.gov/units/">
>   <Description about="John_Smith">
>     <n:weight rdf:parseType="Resource">
>       <n:Pounds>200</n:Pounds>
>       <n:Kilograms>91</n:Kilograms>
>     </n:weight>
>   </Description>
></RDF>
>
>
>Such an approach allows for additive extensions of models to support
>additional measurement systems, rather than requiring the transformation of
>a model from say a metric to an imperial system. Moreover, if the weight
>node were not anonymous, then this addition could come from a separate
>document generated automatically by say a units' conversion program.
>
>A particularly nasty variant is the English habit of quoting body weights in
>Stone and Pounds, so if John lives in London, England, he weighs 14 Stone
>and 4 pounds, extending the graph further gives:
>
><RDF
>   xmlns="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
>   xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
>   xmlns:n="http://www.nist.gov/units/">
>   <Description about="John_Smith">
>     <n:weight rdf:parseType="Resource">
>       <n:Pounds>200</n:Pounds>
>       <n:Kilograms>91</n:Kilograms>
>       <n:Stone rdf:parseType="Resource">
>           <n:Stone>14</n:Stone>
>           <n:Pounds>4</n:Pounds>
>       </n:Stone>
>     </n:weight>
>   </Description>
></RDF>
>
>where the semantics of the pair of arcs <n:Pounds>200</n:Pounds> and
><n:Stone rdf:parseType="Resource"/> is that of alternative description,
>whereas the pair of arcs <n:Stone>14</n:Stone> & <n:Pounds>4</n:Pounds>
>
>
>Jeremy Carroll
>HP Labs, Bristol

------------
Graham Klyne
GK@NineByNine.org
Received on Tuesday, 13 March 2001 13:06:47 GMT

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