Contraposition
jonaprieto opened this issue · 0 comments
jonaprieto commented
We require some theorems about contraposition:
p => q
-------
¬ q => ¬ p
¬ q => ¬ p
----------
p => q
(p => q) <==> (¬ q => ¬ p)
In the implication module is present the second one of these.