CONTRAPOSITIVE

"In mathematics, the contrapositive is a logical statement formed by swapping the hypothesis and conclusion of a conditional statement."

"To prove a theorem, one can use either a direct proof, a proof by contradiction, or a proof by contrapositive."

"The contrapositive of the statement 'If it is raining, then the ground is wet' is 'If the ground is not wet, then it is not raining.'"

"In logic, the contrapositive of the statement 'All birds can fly' is 'All birds that cannot fly are not birds.'"

"In geometry, the contrapositive of the statement 'If two lines are parallel, then their slopes are equal' is 'If two lines do not have equal slopes, then they are not parallel.'"