Conjunction Equivalent to Negation of Implication of Negative/Formulation 1/Forward Implication

Theorem

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

Proof

 * align="right" | 5 ||
 * align="right" | 1, 2
 * $\neg q$
 * $\implies \mathcal E$
 * 2, 3
 * ... and show that the assumption leads to a contradiction
 * align="right" | 6 ||
 * align="right" | 1, 2
 * $\bot$
 * $\neg \mathcal E$
 * 4, 5
 * $\neg \mathcal E$
 * 4, 5