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

Theorem

Formulation 1

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

Formulation 2

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


Also see


Sources

  • 1998: David Nelson: The Penguin Dictionary of Mathematics (2nd ed.) ... (previous) ... (next): De Morgan's laws
  • 2008: David Nelson: The Penguin Dictionary of Mathematics (4th ed.) ... (previous) ... (next): De Morgan's laws
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