The most normal forms for fuzzy logics are versions of conjunctive and disjunctive classical normal forms. Unfortunately, they do not always preserve neither tautologies nor contradictions which is fundamental for automatics theorem provers based on refutations methods.
De Morgan implicative systems are triples like to De Morgan system, but considering fuzzy implications instead of t-conorms. These systems can be used to evaluate the formulas of a propositional language based on the logical connectives of negation, conjunction and implication. Therefore, determines different fuzzy logics, called of De Morgan implicative.
In this paper, we will introduce a normal form for that language and we will show that for the case of fuzzy logics De Morgan implicative whose t-norms are strict, that normal form preserve contradictions as much as tautologies.