De Morgan's Laws (Logic)/Disjunction of Negations/Formulation 1/Forward Implication

Theorem

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

Proof

 * align="right" | 6 ||
 * align="right" | 2, 5
 * $\bot$
 * $\neg \mathcal E$
 * 3, 5
 * 3, 5


 * align="right" | 8 ||
 * align="right" | 2, 7
 * $\bot$
 * $\neg \mathcal E$
 * 4, 7
 * align="right" | 9 ||
 * align="right" | 1, 2
 * $\bot$
 * $\lor \mathcal E$
 * 1, 5-6, 7-8
 * $\bot$
 * $\lor \mathcal E$
 * 1, 5-6, 7-8