Determine whether each statement is true or false. Provide a brief justification for your answer.

$($a$)$ An expression in DNF is always in CNF$.$

Solution

False. $xy+w$ is in DNF$,$ but not CNF$.$

$($b$)$ An expression in CNF is always in DNF$.$

Solution $v$

$($c$)$ An expression in CNF could possibly also be in DNF$.$

Solution

$($d$)$ Every Boolean expression is either CNF or DNF$.$

Solution $v$