Clause Form

Any boolean formula can be put into conjunctive normal form (CNF).

If not Y then X and not Z.

Y or (X & not Z)

(Y or X) & (Y or not Z)

(X V Y) & (Y V ~Z)

clauses: (X V Y), (Y V ~Z)

X, Y, and ~Z are called literals.

Each clause is a disjunction of literals.

A formula in CNF is a conjunction of clauses.

For our example with the butler, we get the following clause:

~ P V ~ Q V R

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