A well-formed formula of the propositional calculus is in conjunctive normal form when it is of the form A & B &…where each of A, B…is a formula consisting of a disjunction of atomic propositions or negations of atomic propositions (e.g. p ∨ q ∨ ¬r…). In disjunctive normal form it is a disjunction of conjuncts subject to the same condition.