Re: [rules-users] Existensial not question
Bryan,
I'm not sure I completely understood your scenario, but Drools supports
FOL and your scenario can be implemented whatever it is.
I think the best way is giving you some examples:
rule "Fires FOR EACH fact that does not have a corresponding Exception
Range"
when
Fact1($number : number)
not ExceptionRange(startRange <= $number, stopRange >= $number)
then
// do something
end
rule "Fires only IF ALL Facts have a corresponding Exception Range (this
rule will fire only once)"
when
not (
Fact1($number : number) and
not ExceptionRange(startRange <= $number, stopRange >= $number)
)
then
// do something
end
rule "SAME AS ABOVE: Fires only if all Facts have a corresponding Exception
Range (this rule will fire only once)"
when
forall( Fact1($number : number)
ExceptionRange(startRange <= $number, stopRange >= $number) )
then
// do something
end
rule "Fires only if THERE IS ANY Fact that does not have a corresponding
Exception Range (this rule will fire only once)"
when
not( forall( Fact1($number : number)
ExceptionRange(startRange <= $number, stopRange >=
$number) ) )
then
// do something
end
rule "fires FOR EACH PAIR [fact, exception range] (cross product)"
when
Fact1($number : number)
ExceptionRange(startRange <= $number, stopRange >= $number)
then
// do something
end
rule "fires if THERE ARE NO facts that have a corresponding exception range
(fires only once)"
when
not (
Fact1($number : number) and
ExceptionRange(startRange <= $number, stopRange >= $number)
)
then
// do something
end
Take a look at the "exists" qualifier that is the same as "not( not(
...
) )".
Hope it helps.
[]s
Edson
2007/9/19, wasabifan <bryan.rickman(a)kewill.com>:
I have several rules I am working on that I am having problems
implementing.
Most of our tests are composed of at least one "pass" and one "fail"
rule.
Basically, there are some tests where exceptions need to be thrown based
on
a date or number being inside a range where these exceptions occur
(causing
a possible failure).
The problem is that we are testing several objects, so using the
existensial
not, is problematic.
For example, in the pass, if we write:
rule "pass example"
when
Fact1($number : number)
not ExceptionRange(startRange <= $number, stopRange >= $number)
then
System.out.println("Pass" + $number);
end
For the fail, it would be like:
rule "fail example"
when
Fact1($number : number)
ExceptionRange(startRange <= $number, stopRange >= $number)
then
System.out.println("Fail" + $number);
end
Is there a way to rewrite the pass rule, so that it checks the existence
of
a range satisfying each number from Fact1? If I understand not correctly,
it will either pass once, and only once if ANY range matches at least one
number from Fact1. Or it would pass for all Fact1's if any Fact1's match
any exception range.
A little clarification here would be appreciated, and if you know of a
workaround to actually test for getting exactly one and only one pass or
fail (exclusively) for each Fact1 asserted.
Thanks,
Bryan Rickman
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Edson Tirelli
Software Engineer - JBoss Rules Core Developer
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