De Morgan's Laws (Logic)/Conjunction of Negations/Formulation 1/Reverse Implication

Theorem

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

Proof

 * align="right" | 4 ||
 * align="right" | 1, 3
 * $\bot$
 * $\neg \mathcal E$
 * 3, 1
 * 3, 1


 * align="right" | 8 ||
 * align="right" | 1, 7
 * $\bot$
 * $\neg \mathcal E$
 * 7, 1
 * 7, 1