RE: [rules-users] logical 'not' - is there such a construct?
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(a)lists.jboss.org
[mailto:rules-users-bounces@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(a)lists.jboss.org
[mailto:rules-users-bounces@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
>
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--
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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