Modus Tollendo Ponens

Sequent
The modus tollendo ponens is a valid deduction sequent in propositional logic.

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

Variant
Note that the form:

requires Law of Excluded Middle.

Therefore it is not valid in intuitionistic logic.

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