Let ω be a set of variables. we say that a propositional formula is a literal if the formula is equal to x or ¬x for x ∈ ω. we say that a propositional formula on ω is in conjunctive normal form if it is equal to =1 =1 ψi, j , where ψi, j is a literal. let φ be a propositional formula on ω. show using structural induction that there is a propositional formula ψ on ω in conjunctive normal form such that ψ |rho = φ |rho for any assignment rho to ω.