check-duality (a b)

• a,b -- two clutter representing monotone boolean functions

Returns (values dual? non-duality-info contradictory?)

dual? is non-NIL if a and b form dual sets of clauses.

contradictory? is non-NIL if a and b are contradictory and hence not dual.

non-duality-info: a missing clause if they are not dual and not contraditory, a pair of clauses that contradict, or NIL otherwise.

Check duality of two monotone boolean functions.