1.4 Normal Forms
Normal forms are standard shapes for propositional formulas, and they are useful because they make formulas easier to compare, transform, and process by algorithms. Literals and Clauses A literal is either a propositional variable or the negation of a propositional variable. Thus the following are literals: $$ p, \quad ¬p, \quad q, \quad ¬q $$ The formula: $$ ¬(p \land q) $$ is not a literal, because the negation is...