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Re: comment: looking forward to treatment of units of measure for use in RDF Calendar work

From: Christopher Welty <welty@us.ibm.com>
Date: Fri, 30 Sep 2005 20:40:07 -0400
To: Dan Connolly <connolly@w3.org>
Cc: public-swbp-wg@w3.org, public-swbp-wg-request@w3.org
Message-ID: <OFBFFA0B24.78E2E646-ON8525708D.00035402-8525708D.0003ACB9@us.ibm.com>


There is an editors draft of an ontology for timezones available from the 
OEP web page [http://www.w3.org/2001/sw/BestPractices/OEP/].  The 
units&measures work has not gotten started yet.  Elisa & Evan have 
promised to have something to say on it by our f2f.  (nudge, nudge)


Dr. Christopher A. Welty, Knowledge Structures Group
IBM Watson Research Center, 19 Skyline Dr., Hawthorne, NY  10532
Voice: +1 914.784.7055,  IBM T/L: 863.7055, Fax: +1 914.784.7455
Email: welty@watson.ibm.com
Web: http://www.research.ibm.com/people/w/welty/

Dan Connolly <connolly@w3.org> 
Sent by: public-swbp-wg-request@w3.org
09/30/2005 06:44 PM


comment: looking forward to treatment of units of measure for use       in 
RDF Calendar work

We just released a note about the RDF calendar work.
One of the long-standing issues is how to deal with

Note that NY:tz timezone is used as a datatype. Earlier, we used
separate properties for time and timezone, which is initially appealing
but problematic for reasons that are detailed in the
InterpretationProperties pattern.

There's some sense in which 1pm Chicago time is equal
to 2pm New York time, and it's parallel to the way
10 centimeters is 100 millimeters.

Here's the relevant bit of the InterpretationProperties topic:


An intuitively obvious way to model quantities is: 

:building :height [ :magnitude "20"; :units :meter].

But this is a train wreck waiting to happen, because we'd like 

[ :magnitude "20"; :units :meter] = [ :magnitude "2000"; :units 
:building :height [ :magnitude "2000"; :units :centimeter].

but then we get 

:building :height [ :magnitude "20", "2000"; :units :meter, :centimeter]

which is all messed up. 


Use InterpretationProperties to relate quantities to magnitudes: 

:building :height [ :meters "20"; :centimeters "2000" ].


For RdfCalendar, it's not clear whether 11am Chicago time is really the
same as 10am New York time. For iCalendar round-tripping, it's probably
not sufficient to convert everything to Z time, especially when you
consider recurring events. 

It occurred to me that this is a problem with n-ary relations, so
I just took another look at

but I see it's TBD: "For a discussion on how to represent units
and quantities in OWL, please refer to a different note (ref to
be added)".

I look forward to any work in that area. Is there any sort of
draft I could take an early look at?

Dan Connolly, W3C http://www.w3.org/People/Connolly/
D3C2 887B 0F92 6005 C541  0875 0F91 96DE 6E52 C29E
Received on Saturday, 1 October 2005 00:40:26 UTC

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