Modus Ponendo Tollens

Modus Ponendo Tollens
The modus ponendo tollens is a valid deduction sequent in propositional logic:

Variants
The following forms can be used as variants of this theorem:

Also see
The following are related argument forms:
 * Modus Ponendo Ponens
 * Modus Tollendo Ponens
 * Modus Tollendo Tollens