Hello Droolers,

I'm a Drools novice and I'm stuck with a basic rule problem.

In my domain I use a list of abbreviations to describe the conditions of a system.
Before I can check the state of my system I have to verify all applied abbreviations.

The List of abbreviations is not a fixed list it's more like a combination of chars, combined in different ways on fixed positions.

This is a small cutout:

A cutout of possible chars at Position 1: A B C D F H
A cutout of possible chars at Position 2: - A C s n b
A cutout of possible chars at Position 3: - A B E F M
A cutout of possible chars at Position 4: - H L O R U

Now it is allowed to combine the following abbreviations:
(another small cutout)

A--O     A--R     A--U    A--L
BAAO     BAAR     BAAU    BAAL

but it is not allowed to combine this:

AA**     B-** (* stands for all possible chars on a position)

Now I have 2 basic Questions:

1) How can I pick abbreviations that are NOT allowed?
   I think it's easy to say:

   rule "Rule 1"
    when
      a : Abbreviation( pos1 == 'A', pos2 == '-', pos3 == '-', pos4 == 'O' )
    then
      # do something positiv
   end

   But how can I pick up all the wrong combinations without hardcoding them?
   This would end up in a never-ending story.

2) Upgrading the "Rule 1" from my 1st Question I'm looking for a way to make the
   Rules more generic.
   I don't want to hardcode all possible abbreviation combinations.
   How can I realise something like this VERY INFORMAL notation:

   rule "Rule 2"
    when
      a : Abbreviation( pos1 == 'A', pos2 == ['-','D','H'], pos3 == '-', pos4 == ['O', 'R', 'U', 'L'] )
      # If abbreviation looks like A--O, AD-O, AD-U, AH-R, etc. everything is fine.
      # It's time for "Rule 2" to do something positiv
    then
      # do something positiv
   end

   "Rule 2" should find all the abbreviations that are build up according to a set of allowed char combinations.

   OR

   rule "Rule 3"
    when
      a : Abbreviation( pos1 == 'A', pos2 != ['-','D','H'], pos3 != '-', pos4 != ['O', 'R', 'U', 'L'] )
      # If abbreviation looks like AA-O, AB-U, A-AO, A--K, etc. something is wrong.
      # It's time for "RULE 3" to announce something negative
    then
      # announce something negative
   end

   "Rule 3" should filter all the abbreviations that are violating a set of allowed char combinations.

Thanx 2 all droolers in advance.

Pete