Conjunctive Normal Form (CNF) is when a formula: ?
- contains no connectives other than conjunction, disjunction and negation.
- only applies negation to propositional symbols (within literals)
- no conjunction appears in a sub-formula of a formula whose main connective is disjunction
Alternatively, you can see it as a conjunction of one or more formulae, each of which is a disjunction of one or more literals.