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Re: Open Issues: DR scope

From: Phil Archer <parcher@icra.org>
Date: Wed, 05 Dec 2007 11:28:20 +0000
Message-ID: <47568B54.7070309@icra.org>
To: Public POWDER <public-powderwg@w3.org>

Comments inline,

Andrea Perego wrote:
> I would like again to ask for feedback about an issue which must be
> urgently solved, that is, how the scope of a DR is defined.
> 
> The current solution is the following:
> 
> 1  <owl:Class rdf:ID="ResourceOnExampleDotOrg">
> 2    <owl:equivalentClass>
> 3      <owl:Class>
> 4        <rdfs:subClassOf>
> 5          <owl:Restriction>
> 6            <owl:onProperty rdf:resource="&wdr;includeHost" />
> 7            <owl:hasValue>example.org</owl:hasValue>
> 8          </owl:Restriction>
> 9        </rdfs:subClassOf>
> 10     </owl:Class>
> 11   </owl:equivalentClass>
> 12 </owl:Class>
> 
> which literally means "all the resources having a URI host component
> ending with example.org" (i.e., "all the resources hosted by
> *.example.org").

Or example.org - the *. implies that the set is resources on subdomains 
of example.org but not example.org itself (see 
http://www.w3.org/TR/2007/WD-powder-grouping-20071031/#wild)
> 
> So, the question is: does anybody agree that this the correct way to
> define a DR scope? If it isn't, which are the alternative solutions?

Broadly, I believe it is the correct way. The good news is that this 
example is more complicated than we need. There was some surprise on the 
SWCG call the other day that we were using an equivalent class and 
subclass within this. It sounded to me as if we could do it as simply as:

1  <owl:Class rdf:ID="ResourceOnExampleDotOrg">
2    <rdfs:subClassOf>
3     <owl:Restriction>
4        <owl:onProperty rdf:resource="&wdr;includeHost" />
5        <owl:hasValue>example.org</owl:hasValue>
6      </owl:Restriction>
7    </rdfs:subClassOf>
8  </owl:Class>

or in even fewer lines - something we need to experiment with. We need 
to look at the necessary/necessary & sufficient definition and some 
other stuff but personally I am in no doubt that this is pretty much 'it.'

Some experiments I've been planning to do:

1. If you have two restrictions, do you need a parseType Collection 
construct?

2. Does using owl:complementOf mean we can get rid of our 'exclude...' 
properties (I believe so).

I'm not able to spend much time on POWDER this week as I'm in Washington 
for FOSI's big conference but if I were at home, I'd be playing with 
protégé and running SPARQL queries against the data. As you know, I am 
seeking outside help and one way or another we should have this sorted 
within the next week or so. I don't think it's as unclear as you seem to 
- which worries me :-) .

Phil.



-- 
Phil Archer
Chief Technical Officer,
Family Online Safety Institute
w. http://www.fosi.org/people/philarcher/

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Received on Wednesday, 5 December 2007 11:28:45 GMT

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