I am trying to rewrite sentences in a logical language into DNF, and wonder if someone would point out where I'm going wrong. My dim understanding of it is that I need to move And and Not inwards and Or out, but the function below fails, for example:
dnf (Or (And A B) (Or (And C D) E)) And (Or A (And (Or C E) (Or D E))) (Or B (And (Or C E) (Or D E)))
data LS = Var | Not LS | And LS LS | Or LS LS --convert sentences to DNF dnf :: LS -> LS dnf (And (Or s1 s2) s3) = Or (And (dnf s1) (dnf s3)) (And (dnf s2) (dnf s3)) dnf (And s1 (Or s2 s3)) = Or (And (dnf s1) (dnf s2)) (And (dnf s1) (dnf s3)) dnf (And s1 s2) = And (dnf s1) (dnf s2) dnf (Or s1 s2) = Or (dnf s1) (dnf s2) dnf (Not (Not d)) = dnf d dnf (Not (And s1 s2)) = Or (Not (dnf s1)) (Not (dnf s2)) dnf (Not (Or s1 s2)) = And (Not (dnf s1)) (Not (dnf s2)) dnf s = s Thanks, Jim -- View this message in context: http://www.nabble.com/Disjunctive-Normal-Form-tf4733248.html#a13534567 Sent from the Haskell - Haskell-Cafe mailing list archive at Nabble.com.