W3C home > Mailing lists > Public > www-rdf-interest@w3.org > November 2001

Re: Domain/Range: conjuntion or disjuntion??

From: <tarod@softhome.net>
Date: Wed, 21 Nov 2001 11:06:44 GMT
Message-ID: <20011121110644.21847.qmail@softhome.net>
To: Arjohn Kampman <akam@aidministrator.nl>
Cc: www-rdf-interest@w3.org

Arjohn Kampman writes:

> >   Thanks Mr. Kampman, I was reading the document you sent, in concrete the
> > chapter for, and I understand what you explain there, but you can fix it in
> > other way, don't you?
> > 
> >   A -1-> a, B -2-> b
> > 
> >   (note: Subject -Predicate-> Object)
> > 
> > and property 3 is subproperty of 1 and 2 (first of all, I never understood
> > subproperties, I would delete it from the schema)
> >   3 will be a property that expect a instance of A and a instance of B in
> > the domain and a instance of a and b on the range, you can do something
> > like this.
> > 
> >   C -subClassOf-> A, C -subClassOf-> B
> >   c -subClassOf-> a, c -subClassOf-> b
> > 
> >   3 -domain-> C, 3 -range-> c
> > 
> >   You have more sentences but you have exactly the same, and you can add
> > that 
> >   3 -subProperty-> 1, 3 -subProperty->2 
> >   without any interpretation, without inherit ranges and domains.
> 
> You can't just ignore inheritance of domain- and range restrictions. Domains
> and ranges of subproperties should always be at least as restricted as their
> superproperties because of section 2.3.3 of the RDF Schema spec:
> 
> "If some property P2 is a subPropertyOf another more general property P1, and
> if a resource A has a P2 property with a value B, this implies that the
> resource A also has a P1 property with value B."
> 
> Assume P1 has its domain restricted to D1, and P2 does not have any domain
> restrictions. This would allow you to use P2 with resources that are not
> instances of D1. But as P2 is a subPropertyOf P1, D1 will also have property
> P1. This again implies that the resource must be an instance of D1.
> 
  I repeat, I don't understand the meaning of SubPropertyOf it make no
sense for me, and maybe you can force single inheritance for properties,
one property can't not be subproperty of more than one property or domains
and ranges must be exactly the same ones. (I want say that there are a lot
of solutions instead of the proposed, the proposed, in my opinion, is not
the better, and ir raises new problems)

> > 
> >   Finally, I want to repeat, this is a solution for Sesame a RDF based
> > product but not for all RDF based products, RDF should be independent of
> > concrete product necessities.
> 
> I cannot agree with this more, but all of these concrete products should
> adhere to one single interpretation to assure interoperability. Sesame
> deviates from the original union-semantics because that can lead to
> inconsistencies in the model, which is a no-go for all RDF based products.
> 
  ejejejejej, imagine my RDF based system with only simple inheritance, it
won't work with your one, and I don't mind, imagine my model can allow
multiple inheritance, one thing is the syntaxis, and that is common for
everybody, the other thing is the semantic that every application gives to
a model, so, my application can understand one thing and your another
thing, the problem is with the old semantics, both you and me can write
what we want, with the new one, you can write what you want, but I can't
write what I want. Give me an example you can't not represent with the old
model?

> Regards,
> 
> Arjohn
> 
  my bests,
         Marc
 
Received on Wednesday, 21 November 2001 06:41:20 GMT

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