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Re: using owl:restrictions

From: Bijan Parsia <bparsia@isr.umd.edu>
Date: Sat, 18 Feb 2006 23:43:39 -0500
Message-Id: <4ec8f25618adea1f1723db296a4a14c6@isr.umd.edu>
Cc: public-owl-dev@w3.org, www-rdf-logic@w3.org
To: "PL. Miraglia (home)" <pierlu.m@gmail.com>

On Feb 18, 2006, at 3:01 PM, PL. Miraglia (home) wrote:

> consider the following:
>
> <rdfs:subClassOf>
>    <owl:Restriction>
>       <owl:onProperty rdf:resource="#R"/>
>       <owl:someValuesFrom rdf:resource="#P"/>
>    </owl:Restriction>
>    <owl:Class rdf:about="#Q"/>
> </rdfs:subClassOf>
>
> I need some clarifications about this term: are these statements true 
> or false?
>
> 1) The construct above is legal in OWL DL/Full not OWL Lite -- right?

FIrst I want to ask why do you care? It's relatively important to 
distinguish between OWL Full and OWL DL, but much less so for OWL Lite 
and OWL DL. Anyhoo.

This fragment alone (assuming a reasonable outer wrapping element) will 
be owl full because of the lack of type triples for #R and #P (probably 
objectproperty and class).


If the rest of the ontology is like that, I'll bet it is "repairable", 
in which case, this fragment would be in OWL Lite, see:
	http://www.w3.org/TR/owl-semantics/syntax.html#2.3.1

Pellet will suggest the extra type triples:
	http://www.mindswap.org/2003/pellet/demo

Oh, and it's illegal RDF as it will have two object elements as the 
value of one property element.

You may have meant something like this:

<owl:Class rdf:about="#A">
	<rdfs:subClassOf>
	   <owl:Restriction>
		     <owl:onProperty rdf:resource="#R"/>
   		    <owl:someValuesFrom rdf:resource="#P"/>
    		</owl:Restriction>
	</rdfs:subClassOf>
	<rdfs:subClassOf>
    		<owl:Class rdf:about="#Q"/>
	</rdfs:subClassOf>
</owl:Class>

This is an implication (or two implications). In FOL:

(x)(Ax -> (some y)(Rxy & Py))
(x)(Ax -> Qx)

That's a pretty direct transliteration.

> (This is what the Wonderweb validator seems to indicate, although I
> found some of the OWL documents a bit unclear)
>
> 2) It is logically equivalent to the this FOL formula (KIFfy style):
>
> (implies
>     (and (R x y) (P y))
>     (Q x))

Er...don't think so. First off, your fragment above is incomplete. 
Second, I take it that (Q x) is the consequent? See my translation 
above.

> 3) Assuming that IR is the inverse of R, it is also logically 
> equivalent to:
>
> <rdfs:subClassOf>
>    <owl:Class rdf:about="#P"/>
>    <owl:Restriction>
>       <owl:onProperty rdf:resource="#R"/>
>       <owl:allValuesFrom rdf:resource="#Q"/>
>    </owl:Restriction>
> </rdfs:subClassOf>

I clearly don't understand what you are trying to do. Was Q supposed to 
be the LHS of the subsumption?

Cheers,
Bijan.
Received on Sunday, 19 February 2006 04:43:49 GMT

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