Definition:Disjunctive Normal Form

Definition
A logical formula $P$ is in disjunctive normal form (abbreviated DNF) if it consists of a disjunction of:
 * conjunctions of literals, and/or
 * literals,

Examples

 * $\left({\neg p \land q \land r}\right) \lor \left({\neg q \land r}\right) \lor \left({\neg r}\right)$

is in DNF.


 * $\left({\neg p \land q \land r}\right) \lor \left({\left({p \lor \neg q}\right) \land r}\right) \lor \left({\neg r}\right)$

is not in DNF because there is a disjunction buried in the second conjunction.


 * $\left({\neg p \land q \land r}\right) \lor \neg \left({\neg q \land r}\right) \lor \left({\neg r}\right)$

is not in DNF because the second conjunction is negated.


 * $p \lor q$

is in DNF, as it is a disjunction of literals.


 * $p \land q$

is in DNF, as it is a trivial (one-element) disjunction of a conjunction of literals.