Re: OWL-S preconditions - practical issues

> >
> > If I recall correctly, you suggested that Pellet's conjunctive ABox
> > query answering module could be used to evaluate such preconditions.
> 
> Yes.
> 
> > Is
> > this true, and if so, what syntax should they be expressed in if Pellet
> > were to be used for this purpose?
> 
> We will support, via the OWL-S API, the standard OWL-S precondition 
> language, which will be "SWRLlike" as mentioned before.
> 
> We'll have RDQL syntax support as well...so I guess you could use that 
> if you really wanted to.
> 

Am I correct in assuming from your use of the future tense that this is
still in the pipeline? If not, are there any examples available of how
to use Pellet to evaluate SWRL-like conditional expressions. I'd be very
grateful for any additional information about this.

> I was thinking that a planner could do this. Of course, it wouldn't do 
> precisely what you were asking for, since it doesn't determine 
> compatibility in the general case of the *expressions*. But for the 
> purposes of finding compatible *processes* for *composition* it seems 
> sufficiently useful.
> 

The problem with planners is that compatibility of preconditions and
effects is based on (lexical) name matching. Although SHOP2 can evaluate
simple expressions such as ((eval (< ?n1 5)) in the precondition of an
operator, AFAIK, it is not possible to assert an effect which is a
conditional expression, e.g. to state that "the effect of this
process/operator is that (< ?n1 5) is true".

More generally, has there been any attempt to translate OWL-S
preconditions/effects to SHOP2 syntax? For example, to convert an
expression such as:

   <owls:AtomicProcess>
      <owls:hasPrecondition>
	<owls:Expression expressionLanguage="&swrl;#SWRL"
	                 rdf:parseType="Literal">
           <ruleml:body rdf:parseType="Collection">
	      <swrl:individualPropertyAtom>
		 <swrl:propertyPredicate rdf:resource="creditCardAuth"/>
		 <swrl:argument1 rdf:resource="#cc"/>
		 <swrl:argument2 rdf:datatype="&xsd;#string">Yes</swrl:argument2>
	      </swrl:individualPropertyAtom>
           </ruleml:body rdf:parseType="Collection">
	</owls:Expression>
      </owls:hasPrecondition>
   </owls:AtomicProcess>

to:

(creditCardAuth ?cc Yes)


Thanks in advance,
Donal

Received on Friday, 25 June 2004 11:43:35 UTC