Relationen

relation :: ( Ix a, Ix b )
  => ((a,b),(a,b)) -> SAT ( Relation a b )
instance (Ix a, Ix b) 
  => Decode ( Relation a b ) 
            ( Array (a,b) Bool ) ...
product :: ( Ix a , Ix b, Enum b, Ix c )
  => Relation a b -> Relation b c 
  -> SAT ( Relation a c )
transitive :: ( Enum a, Ix a )
           => Relation a a -> SAT Boolean
transitive r = do
    r2 <- product r r
    implies r2 r