Rectified wffs a wff a is rectified iff 1. A contains no vacuous quantifier 2 No variable occurs both bound and free in a 3. No two quantifier-occurrences in a bind the same variable A wff in prenex normal form must be rectified Logic in Computer Science-p. 6/9Rectified Wffs A wff A is rectified iff 1. A contains no vacuous quantifier. 2. No variable occurs both bound and free in A. 3. No two quantifier-occurrences in A bind the same variable. A wff in prenex normal form must be rectified. Logic in Computer Science – p.6/9