[rules-users] Predicate Logic rule-binding clarification

[Edson Tirelli]

   Hey Wolfgang,

   Timely mention! :) I was talking to Jason Morris here at ORF last
saturday and he pointed me to your paper. I read it and it is very good
indeed. :)

   Now, I have a question for you. Without trying this in any engine
(neither Drools, not Jess, nor Clips), tell me what do you expect would
happen in the next scenario (I will use Drools syntax, but after trying to
answer, you can convert that to jess, clips, etc to run it).

rule "Testing For All"
when
    forall( Alarm( sev == "critical" ) )
then
    System.out.println("test forall fired");
end

   Where alarm is:

Alarm {
int sequential;
String sev;
}

   Scenario is:

1. Add the rule to a kbase, and create a session
2. fire all rules
3. insert alarm( 1, "critical");
4. fire all rules
5. insert alarm( 2, "critical");
6. fire all rules

   Question is: in which steps do you expect the rule to fire? :)

   Cheers,
      Edson


2009/10/26 Wolfgang Laun <wolfgang.laun at gmail.com>

> Yes, that's what Drools and other forward chaining inference engines do.
>
> People have found http://www.jessrules.com/jess/docs/PropPred.pdf helpful.
> Even though the syntax isn't Drools, you shouldn't have any problems
> following this monograph.
>
> -W
>
>
>
> On Mon, Oct 26, 2009 at 1:01 PM, dbrownell83 <dbrownell83 at hotmail.com>wrote:
>
>>
>> Hi,
>>
>> I am new to Drools, so this might be an obvious 'yes' answer...
>>
>> I see that DRL uses "first order predicate logic" for its syntax.
>> That is, it models things like "For all X, such that Y, do Z"
>>
>> Am I correct that as long as some data in the knowledge session matches
>> the
>> 'when' conditions, it will run the 'then' consequence?
>>
>> Is that how it works?  Is this basically what the Rete algorithm does?
>>
>> Thanks
>>
>>
>>
>> --
>> View this message in context:
>> http://www.nabble.com/Predicate-Logic-rule-binding-clarification-tp26058455p26058455.html
>> Sent from the drools - user mailing list archive at Nabble.com.
>>
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>
>
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-- 
 Edson Tirelli
 JBoss Drools Core Development
 JBoss by Red Hat @ www.jboss.com
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