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places and lists of coordinates [was: priority bug, to libby and dan]

From: Dan Connolly <connolly@w3.org>
Date: Thu, 08 Apr 2004 10:07:21 -0500
To: Masahide Kanzaki <post@kanzaki.com>
Cc: www-rdf-calendar@w3.org
Message-Id: <1081436841.16752.11502.camel@dirk>

On Thu, 2004-04-08 at 09:57, Masahide Kanzaki wrote:
> At 9:16 AM -0500 04.4.8, Dan Connolly wrote:
> >Just yesterday, in consultation with SeanP, I decided
> >to represent the floats in GEO as real RDF floats:
> >
> >       <geo
> >           rdf:parseType="Resource"
> >          ><rdf:first
> >             rdf:datatype="http://www.w3.org/2001/XMLSchema#double"
> >            >40.442673</rdf:first
> 
> Interesting. In this way, you describe the object of ical:geo as an
> anonymous resource,

well, yes...

>  which implies ical:geo is an owl:ObjectProperty and has
> no specific range.

no... its range is: list of float:


	    <rdfs:range>
	      <!-- We could express the semantics of this class ala:
	        :FloatList subClassOf rdf:List,
	          [owl:onProperty rdf:first; owl:allValuesFrom :FloatLit ],
	          [owl:onProperty rdf:rest; owl:allValuesFrom :FloatList ].

		  I think "list of X" is discussed in the OWL specs
		  somewhere.
	      -->
	      <owl:Class rdf:about="#List_of_Float"/>
	    </rdfs:range>
  -- http://www.w3.org/2002/12/cal/webize2445.xsl

>  Then, it becomes possible to write as:
> 
>  <ical:geo rdf:parseType="Resource">
>   <geo:lat>35.678</geo:lat>
>   <geo:long>139.770</geo:long>
>  </ical:geo>

Hmm... that would be saying there's a list of foats at 35,139 on
the globe. I don't think that's wise.

> If anybody wants to describe coordinates in a manner strictly following to
> the RFC 2445, then he/she can use your syntax (first - rest - nil).

The first/rest syntax is the RDF standard way to write lists.

> If, on the other hand, want to describe a place with WGS84, we can use
> geo:lat/geo:long here (this might not be safely converted back to
> iCalendar, because there is no way to specify datum).
>
> It looks happy solution for both sides. Isn't it ?

You can relate the list of floats to the place on the globe, but
I don't think it's a good idea to equate them.

-- 
Dan Connolly, W3C http://www.w3.org/People/Connolly/
see you at the WWW2004 in NY 17-22 May?
Received on Thursday, 8 April 2004 11:06:49 UTC

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