Clause Form

UsesElectricity(x) V Not Macintosh(x).

Clause form for predicate calculus expressions is similar to that for propositional calculus expressions.

To achieve clause form, several steps may be required.

a. Rewrite X -> Y expressions as ~ X V Y.

b. Reduce scopes of negation.

c. Using strict rules, eliminate quantifiers.

If the scope of a universal quantifier is the whole formula,

then drop the quantifier, the quantification will be implicit.

Using Skolem constants and or Skolem functions, remove

any existential quantifiers.

d. Convert to conjunctive normal form