Re: RIF and QL

From: jos.deroo@agfa.com
Subject: Re: RIF and QL
Date: Fri, 27 Jan 2006 20:17:05 +0100

> Peter F. Patel-Schneider wrote:
> >> [...]
> >>> Take, for example, the case in <http://www.w3.org/2005/rules/wg/wiki/ 
> >>> Managing_incomplete_information#disjunctive-info>, which I rephrase 
> >>> below.
> >>>
> >>> Given a KB with the only axiom:
> >>>
> >>>    kb:customer rdfs:subClassOf unionOf(kb:paysCash kb:paysCC).
> >>>
> >>> and the fact:
> >>>
> >>>    kb:customer("Paul").
> >>>
> >>> and the rules:
> >>>
> >>>    cons:paying-customer(X) :- kb:customer(X), kb:paysCC(X).
> >>>    cons:paying-customer(X) :- kb:customer(X), kb:paysCash(X).
> >>>
> >>> we actually get, as expected, with either SWRL FOL semantics or 
> >>> Rosati's style LP semantics:
> >>>
> >>>    cons:paying-customer("Paul").
> >>>
> >>> But with the local evaluation of each body I don't get it.
> >> 
> >> 
> >> Well, maybe I'm sleeping, but when instead of your 2 rules (in N3)
> >> {?X a kb:customer. ?X a kb:paysCC} => {?X a cons:paying-customer}.
> >> {?X a kb:customer. ?X a kb:paysCash} => {?X a cons:paying-customer}.
> >> 
> >> I use a single rule
> >> {?X a ?C. ?C owl:unionOf (kb:paysCash kb:paysCC)} => {?X a 
> >> cons:paying-customer}.
> >> 
> >> then given the facts
> >> kb:customer rdfs:subClassOf [ owl:unionOf (kb:paysCash kb:paysCC)].
> >> :Paul a kb:customer.
> >> 
> >> and given the rules
> >> http://www.agfa.com/w3c/euler/rpo-rules.n3
> >> 
> >> I'm getting proof evidence (*) for
> >> :Paul a cons:paying-customer.
> >> 
> >> What am I missing??
> >
> > Well, perhaps, that you changed the rule, which is stepping outside
> > of the permissable actions?
> 
> Really? :-)
> I would have thought that
> 
> {?X a kb:customer.
>  ?X a ?C.
>  ?C owl:unionOf (kb:paysCash kb:paysCC)}
> =>
> {?X a cons:paying-customer}.
> 
> and
> 
> {?X a kb:customer.
>  ?X a kb:paysCC}
> =>
> {?X a cons:paying-customer}.
> 
> {?X a kb:customer.
>  ?X a kb:paysCash}
> =>
> {?X a cons:paying-customer}.
> 
> are equivalent rulesets, no?
> 
> -- 
> Jos De Roo, AGFA http://www.agfa.com/w3c/jdroo/

Well obviously not at least in some readings, as they produce different
answers.

peter

Received on Friday, 27 January 2006 20:02:23 UTC