[rules-users] how "exists" works exactly?

[Steve Ronderos]

Antonio,

I think that the problem may not be the exists.  I'm not an expert at 
solver, but I believe that there may be an issue with the consequence of 
your first rule.

insertLogical(new IntConstraintOccurrence("diff", 10));

The way that insertLogical works the new object will only be inserted if 
it does not .equals() with another fact in the working memory (or maybe in 
the truth maintenance system).  Without seeing the rest of the solver 
(moves and such) I can't say for certain, but I think that each move is 
being evaluated to the same weight because the 1st rule will never result 
in a constraint occurrence > 10.  Multiple matches of that rule will only 
result in one IntConstraintOccurrence being inserted.

Maybe Wolfgang or someone else a little more experienced can verify my 
assumptions about how insertLogical works.

Thanks,
Steve

rules-users-bounces at lists.jboss.org wrote on 05/05/2010 04:07:37 AM:

> [image removed] 
> 
> Re: [rules-users] how "exists" works exactly?
> 
> Wolfgang Laun 
> 
> to:
> 
> Rules Users List
> 
> 05/05/2010 04:15 AM
> 
> Sent by:
> 
> rules-users-bounces at lists.jboss.org
> 
> Please respond to Rules Users List
> 
> One thing I've noticed is that
>    not (exists (EPackage(   ) ) )
> is a roundabout (and possibly inefficient) way of saying
>    not (EPackage( ... ) )
> 
> It's difficult (for me) to deduce what should happen in the rules as
> the description of the
> fact data isn't clear enough (for me).
> 
> -W
> 
> 2010/5/5 Antonio Neto <antoniosouzaneto at gmail.com>:
> > Any idea? Please...
> >
> > 2010/5/4 Antonio Neto <antoniosouzaneto at gmail.com>
> >>
> >> Hi all,
> >>
> >> I don't know exactly why I have a problem in my "exists" function. 
I've
> >> tried many different ways, but it does not work. Anybody could help 
me,
> >> please?
> >>
> >> I have the following rules:
> >>
> >> rule "diff"
> >> when
> >>     $var1: EReference(name == "employee")
> >>     $var2: EClass(name == "Company", EAllReferences contains $var1)
> >>     not (exists( EPackage(EClassifiers contains $var2 ) ))
> >> then
> >>     insertLogical(new IntConstraintOccurrence("diff", 10));
> >> end
> >>
> >> rule "ClassesNotReferenced"
> >>     when
> >>         $q1 : EClass();
> >>         $q2 : EPackage(EClassifiers contains $q1);
> >>         not( exists ( EReference(EType == $q1) ));
> >>     then
> >>         insertLogical(new 
IntConstraintOccurrence("ClassesNotReferenced",
> >> 1, $q1));
> >> end
> >>
> >>
> >> and in my facts (and my EPackage) I have 4 instances of EClass 
"Company"
> >> with a EReference "employee", and another EClass "Person".  I still 
have a
> >> "move" that removes EClasses in my Drools Solver.
> >>
> >> I need to have only one classe "Company" after processing. But it 
removes
> >> only the EClass "Person", when it was supposed to remove one 
> EClass "Person"
> >> and 3 ECLasses "Company". Leaving one EClass "Company" in the end.
> >>
> >> The problem is:  when Drools tries to remove a EClass "Person" it 
thinks
> >> that  the EClass "Company" does not exists. But in fact there are3 
others.
> >>
> >> Any clue about it, please ?
> >>
> >> Thanks
> >>
> >> Bests regards
> >>
> >> Antonio
> >>
> >>
> >
> >
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> >
> >
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