[rules-users] Solving Conflict Resolution on values ​​of the facts - Help

[Wolfgang Laun]

According to the spec the selection must find the most experienced,
with age as a tie breaker.

A single rule is sufficient:
    $p: Person( $xp: experience, $age: age )
    not Person( experience > $xp || experience == $xp && age > $age )

Although you can write even more complex constraints, it might not be
convenient. An evaluation function like the following could be
considered
(as long as long is sufficient):
   long rating( int a, int b, int c ){
     return ((long)a*AMAX + b)*BMAX + c;
   }

Or, using accumulate, the best can be found by coding
init/action/result explicitly (or implement this as a custom
accumulate function);
    $best: Person() from
       accumulate ( $p: Person( $e: experience, $a: age ),
                    init( Person best = null; int ex = -1; ),
                    action( if( $e > ex || $e == ex && $a > best.getAge() ){
                                       best = $p; ex = $e; } ),
                     result( best ) )

-W


On 12/06/2012, Davide Sottara <dsotty at gmail.com> wrote:
> -- You have several options.. one is the more declarative:
>
> $best : Person( $xp : experience )
> not Person( experience > $xp )
>
> -- Another option is to accumulate and find the highest level of
> experience:
>
> accumulate( Person( $xp : experience ), $max : max ( $xp ) )
>
> then you can match against that, either directly or inserting that value as
> a fact:
> $best : Person( $exp : exp >= $max )
>
> -- which leads to a possible solution for the multi-criteria case, creating
> score facts:
> when
>  $p : Person( $xp : experience, $a: age )
> then
>  insert( new Score( $p, /* an appropriate function of your xp and age */ )
> );
> end
>
> at this point, the previous options apply to the score facts directly.
>
> -- Of course there are other variations and possibilities
> Davide
>
> btw, are you assuming that no other Person will be insert after the best
> has
> been chosen, right?
>
> --
> View this message in context:
> http://drools.46999.n3.nabble.com/Solving-Conflict-Resolution-on-values-of-the-facts-Help-tp4017876p4017877.html
> Sent from the Drools: User forum mailing list archive at Nabble.com.
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