SWRL expression in a property instance?

From: David Martin (martin@AI.SRI.COM)
Date: 02/11/05

  • Next message: Peter F. Patel-Schneider: "Re: SWRL expression in a property instance?"
    Greetings Mike and all joint committee folks -
    
    Lest you guys get bored, a bunch of us are grappling with the question 
    of how to use a SWRL expression as the value of a property instance, and 
    I'd very much appreciate your views on this.
    
    For example, in OWL-S an AtomicProcess has a precondition, which we want
    to express in SWRL.  Here's a simplistic example of the kind of thing we
    might like to do:
    
    <AtomicProcess>
       <hasPrecondition>
         <ruleml:Imp>
           <ruleml:body>
             <!-- empty body -->
           </ruleml:body>
           <ruleml:head>
            <swrl:IndividualPropertyAtom>
              <swrl:propertyPredicate
                rdf:resource="&eg;hasCreditCardOfType"/>
              <swrl:argument1 rdf:resource="#user" />
              <swrl:argument2 rdf:resource="#VISA" />
            </swrl:IndividualPropertyAtom>
           </ruleml:head>
         </ruleml:Imp>
       </hasPrecondition>
       ....
    </AtomicProcess>
    
    This says that the precondition for the atomic process is that the user 
    must have a VISA card (user is a variable that will get bound to some 
    kind of user ID, when the process runs).
    
    So here are my questions:
    
    (1) Is this legal to use an Imp instance in this way, as the value of a 
    property instance?
    
    (1a) In general, can SWRL classes like Imp and IndividualPropertyAtom be 
    instantiated and used in all the same ways that ordinary OWL classes can 
    be used in OWL-DL?  (Is it even right to think of these as OWL classes?)
    
    (2) If the above example is legit, how about if we omit the Imp and body 
    and head elements, and just nest the IndividualPropertyAtom directly 
    inside the hasPrecondition tag?
    
    (3) If the answer to (1) or (2) is "no" - is it any different for SWRL-FOL?
    
    (4) If the above example is legit, and *if* we forget about RDF 
    semantics, will a SWRL reasoner treat the Imp as if it were a non-nested 
    assertion, and try to reason with it?  Or will it simply record that 
    there's an Imp instance related to an AtomicProcess instance?
    
    Thanks!
    
    - David Martin
    (on behalf of various people working on OWL-S and Protege-based OWL editors)
    


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