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Re: RE : Suggestion for SKOS FAQ

From: Stephen Bounds <km@bounds.net.au>
Date: Wed, 12 Mar 2008 08:39:49 +1100
Message-ID: <47D6FC25.9020306@bounds.net.au>
To: SKOS <public-esw-thes@w3.org>
CC: "Sini, Margherita \(KCEW\)" <Margherita.Sini@fao.org>, al@jku.at

Hi Margaret & Andy,

I thought that too when I first looked at the SKOS Primer, but you need 
to remember that OWL sub-properties are subtractive, not additive.

Another way of putting this is that super-properties make *less* 
restrictive statements about the world.

The full hierarchy of skos:broader is:

  skos:semanticRelation
   skos:broaderTransitive
    skos:broader

Which means that for A skos:broader B, this entails that:

  A skos:broaderTransitive B  and
  A skos:semanticRelation B

We can't reverse the order of skos:broaderTransitive and skos:broader in 
the because of the transitive case.  If:

   A skos:broaderTransitive B  and
   B skos:broaderTransitive C  then
   A skos:broaderTransitive C  but

   A skos:broader C   is NOT entailed

If skos:broader were a super-property of skos:broaderTransitive, this 
statement would also need to be true.

Regards,

-- Stephen.

Sini, Margherita (KCEW) wrote:
> I agree with Andy, I also think it should be a sub-property, not a 
> super-property...
>  
> Regards
> Margherita
> 
>     -----Original Message-----
>     *From:* public-esw-thes-request@w3.org
>     [mailto:public-esw-thes-request@w3.org] *On Behalf Of *Andreas Langegger
>     *Sent:* 11 March 2008 12:14
>     *To:* Alasdair J G Gray
>     *Cc:* Antoine Isaac; Simon Spero; iperez@babel.ls.fi.upm.es; SKOS
>     *Subject:* Re: RE : Suggestion for SKOS FAQ
> 
>     Hi,
> 
>     first I din't pay much attention to your discussion, because I
>     thought this case is clear... looking at the spec I read
>     "skos:broaderTransitive owl:subClassOf skos:broader" - but there it
>     says (to my surprise): skos:broaderTransitive and others are "super
>     properties" - why that?
> 
>     If I would model this I would say:
> 
>     skos:semanticRelation a owl:ObjectProperty .
>     skos:broader a skos:semanticRelation .
>     skos:narrower a skos:semanticRelation .
>     skos:broaderTransitive a skos:broader; a owl:TransitiveProperty .
>     skos:narrowerTrasnsitive a skos:narrower; a owl:TransitiveProperty .
>     and so on...
> 
>     can anybody comment on this why the specs says "super property" and
>     not "sub property" ?
>     Whith the statements above I can deceide whether to allow
>     transitivity or not. And because of OWA, skos:broader not explicitly
>     asserted as a transtive property, it does not mean, that it _cannot
>     be_ transitive, sure it can, but it does not need to be valid.
> 
>     If a taxonomy should be ISO2788 compliant, just use the *Transitive
>     versions - so it's up to the modeler and not to the application
>     which I think is fine.
> 
>     regards
>     Andy
Received on Tuesday, 11 March 2008 21:40:08 GMT

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