[rules-users] logical 'not' - is there such a construct?

[Olenin, Vladimir (MOH)]

Well, probably to rephrase it, what is the status / thoughts on 'else'
construct for rules? Basically global 'logical' not for rules would be the
'else' branch of conditional statement (if DROOLS had one), correct? I've
read some postings regarding this shortly after I joined the list (ie,
around a month ago). I wonder if that discussion went anywhere....


To clarify, I do need the _logical_ not, NOT exisitential. So that the
constructs with logical 'not' would select an 'inverse' fact tuples, ie,
tuples for facts that did not the condition.... Kind of simple logical
statement transformation in boolean algebra (DeMorgan law?...):


   MyObject( field == 'value' )  and MyObject2( field == 'value' )   --->
!( MyObject( field != 'value' )   or MyObject2( field != 'value' ) )


If '!' would mean "ALL TUPLES FOR FACTS IN THE RULE" XOR "SELECTED TUPLES",
would the above conditions select the same set of tuples? I assume the
engine should just 'expand' any such 'logical not' operands to move it into
the coluimn constraints?..

I might be confusing smth though.... On the second thought for my particular
case 'existential' not should work too, so I guess the above is just a
possible extention of functionality. It really has nothing to do with the
rule engine itself (from what I see), but rather transformation of the
logical expressions before they are feeded into the rules engine.

Thanks for the answers, Edson.

Vlad




-----Original Message-----
From: rules-users-bounces at lists.jboss.org
[mailto:rules-users-bounces at lists.jboss.org] On Behalf Of Edson Tirelli
Sent: 20 February 2007 16:30
To: Rules Users List
Subject: Re: [rules-users] logical 'not' - is there such a construct?

    No, the "not" conditional element is an existential operator, so the 
meaning is what you expressed in your first example. I thought that was 
what you were looking for, but apparently it is not.
    I never heard about any construction capable of doing what you are 
asking for in a rules engine... maybe someone else can throw some light 
in...

    []s
    Edson

Olenin, Vladimir (MOH) wrote:

>So, if used like that, 'not' does not have 'existential' meaning then, but
>simple 'negation'? I mean, the expression
>
>   not MyObject(field == 'value')
>
>would still mean 'not exists', correct? Would the expression
>
>   not (MyObject(field == 'value'))
>
>mean 
>
>   MyObject(field != 'value')
>
>then. In other worlds, "all objects OTHER then those matching the
>constraint"?
>
>Thanks.
>
>Vlad
>
>-----Original Message-----
>From: rules-users-bounces at lists.jboss.org
>[mailto:rules-users-bounces at lists.jboss.org] On Behalf Of Edson Tirelli
>Sent: 20 February 2007 14:37
>To: Rules Users List
>Subject: Re: [rules-users] logical 'not' - is there such a construct?
>
>  Vlad,
>
>In 3.1M1 you can write:
>
>rule X
>when
>not (
>MyObject( aaa == "bbb" ) and
>MyObject2( bbb == "aaa" )
>)
>then
>// do something
>end
>
>But remember that variables bound inside the "not" block are not avaible 
>in the consequence for obvious reasons.
>
>[]s
>Edson
>
>Olenin, Vladimir (MOH) wrote:
>
>  
>
>>Hi,
>>
>>I wonder if there is logical 'not' operator (in the meaning of "!=" -> 
>>'not equal') which can be applied to the whole rule? Eg:
>>
>>Rule x
>>
>>When
>>
>>! (
>>
>>MyObject(aaa == "bbb")
>>
>>MyObject2(bbb == "aaa")
>>
>>)
>>
>>Then
>>
>>// do smth
>>
>>End
>>
>>Basically I'm looking for an operator to reverse the evaluation result 
>>of the expression in the brackets. The use case: in my system all 
>>rules are defined from 'rule passes' prospective, while the 
>>application should take some action in case the rule is NOT passed 
>>(ie, 'else' case).
>>
>>Any way to do that except reformulating the constraints themselves?
>>
>>Thanks,
>>
>>Vlad
>>
>>------------------------------------------------------------------------
>>
>>_______________________________________________
>>rules-users mailing list
>>rules-users at lists.jboss.org
>>https://lists.jboss.org/mailman/listinfo/rules-users
>> 
>>
>>    
>>
>
>
>  
>


-- 
 Edson Tirelli
 Software Engineer - JBoss Rules Core Developer
 Office: +55 11 3124-6000
 Mobile: +55 11 9218-4151
 JBoss, a division of Red Hat @ www.jboss.com


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