Double Negation/Double Negation Introduction/Sequent Form/Formulation 1/Proof

Theorem

 * $p \vdash \neg \neg p$

Proof

 * align="right" | 3 ||
 * align="right" | 1, 2
 * $\bot$
 * $\neg \mathcal E$
 * 1, 2
 * 1, 2