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Re: owl:TopObjectProperty in property chains?

From: Jeff Thompson <jeff@thefirst.org>
Date: Tue, 26 Aug 2008 08:50:45 -0700
Message-ID: <48B42655.6000705@thefirst.org>
To: public-owl-dev@w3.org

Uli Sattler wrote:
 >>  In
 >> other words, suppose you have the OWL 2 axiom:
 >>
 >> ObjectProperty: childRelatedToBrother
 >>  SubPropertyChain: hasParent o owl:TopObjectProperty o hasBrother
 >>
 >> would that be the same as this rule:
 >> hasParent(x, y) ^ hasBrother(w, z) -> childRelatedToBrother(x, z)
 >>
 >> In other words, the parent of x does not need to be the same as the brother of z.
 >>
 >
 > Now this example looks very strange indeed: could you explain to us what the idea behind it is? 
Cheers, Uli

I'm trying to fill out the table of combinations of variables for rules
which can be converted to axioms without variables.  You already have:

hasParent(x, y) ^ hasBrother(y, z) -> hasUncle(x, z)

and

hasPerformer(x, y) ^ loves(y, y) -> hasPrimadonna(x, y)

How about this one:

hasParent(x, y) ^ ownsCastle(y, z) -> hasRichParent(x, y)

Notice that the consequent has (x, y), not (x, z) so that z is unbound.  I think this
can done by turning ownsCastle(y, z) into a class description for y like OwnsCastle(y) with
a someValuesFrom restriction on ownsCastle

Class: OwnsCastle  SubClassOf: ownsCastle some owl:Thing

Then the rule becomes one which can be converted to OWL:

hasParent(x, y) ^ OwnsCastle(y) -> hasRichParent(x, y)

You see what I'm getting at.  In general, I'm interested in the way that
"Rewriting Rules into SROIQ Axioms" turns
rules with variables into axioms without variables.  Is there other work which turns
all the forms of rules into axioms without variables, even if they aren't tractable OWL axioms?

- Jeff
Received on Tuesday, 26 August 2008 15:51:25 GMT

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