De Morgan's Laws (Logic)/Disjunction of Negations

Theorems

Formulation 1

$\neg p \lor \neg q \dashv \vdash \neg \paren {p \land q}$

Formulation 2

$\vdash \paren {\neg p \lor \neg q} \iff \paren {\neg \paren {p \land q} }$