Conjunction and Implication

Modus Ponendo Tollens (abbreviated $\textrm{MPT}$)
The following can also be seen to hold:

which follow immediately from
 * $\left({p \land \neg q}\right) \iff \left({\neg \left({p \implies q}\right)}\right)$

and the rule of simplification.

Comment
Note that the Modus Ponendo Tollens:
 * $\neg \left({p \land q}\right) \dashv \vdash p \implies \neg q$

can be proved in both directions without resorting to the LEM.

All the others:


 * $p \land q \vdash \neg \left({p \implies \neg q}\right)$
 * $p \implies q \vdash \neg \left({p \land \neg q}\right)$
 * $p \land \neg q \vdash \neg \left({p \implies q}\right)$

are not reversible in intuitionist logic.