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Re: ontology for units of measurement and/or physical quantities

From: Joshua Tauberer <jt@occams.info>
Date: Mon, 09 Oct 2006 11:05:08 -0400
Message-ID: <452A6524.7030802@occams.info>
To: semantic-web@w3.org

Just a thought on an old topic...

Robert Didier wrote:
> I am interested in the problem of communicating physical quantities,
> e.g. between a web service and its client.

Something that I hadn't seen suggested is encoding units within the
literal value, like:

mysphere speed "32 m/s"^^unitizedReal

with an appropriate definition of the unitizedReal data type so that 1)
the unit can be parsed and 2) the value space collapses different
lexical representations of the same value, i.e. so that these lexical
forms all are said to have the same value (modulo rounding):

"1000 g"
"1 Kg"
"2.2 lbs"

I'm not sure, but I think this still works if 'mass' is a functional
property because

  mysphere mass "1000 g"^^unitizedReal .
  mysphere mass "1 Kg"^^unitizedReal .

would entail

  "1000 g"^^unitizedReal = "1 Kg"^^unitizedReal

which is true because their values are the same.  (I'm just not sure
sure if the equality entailed by a functional property works this way
with datatypes.  Anyone know?)

The big drawback is that dealing with these literals requires a special
parser, but it saves creating a new bnode for each measure (i.e.
mysphere mass [ grams 1000 ] ) and I think is a little easier to
understand compared to having a bnode that represents the notion of the
mass itself independent of its measure.

- Joshua Tauberer


"Strike up the klezmer and start acting like a man. You're
about to have a truth-mitzvah."  -- The Colbert Report
Received on Monday, 9 October 2006 15:05:20 UTC

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