Clause Form
(all x) (Macintosh(x) -> UsesElectricity(x)
UsesElectricity(x) V Not Macintosh(x).
Any boolean formula can be put into conjunctive normal form (CNF).
If not Y then X and not Z.
clauses: (X V Y), (Y V ~Z)
X, Y, and ~Z are called literals.
Each clause is a disjunction of literals.