de Morgan's law

$$\begin{array}{c}\neg (p\wedge q)\equiv (\neg p\vee \neg q)\end{array}$$ $$\begin{array}{c}\neg (p\vee q)\equiv (\neg p\wedge \neg q)\end{array}$$

Alternatively, in boolean logic:

$$\begin{array}{c}\overline{B_0\cdot B_1\cdot B_2\dots }=\left(\overline{B_0}+\overline{B_1}+\overline{B_2}\dots \right)\end{array}$$ $$\begin{array}{c}\overline{B_0+B_1+B_2\dots }=\left(\overline{B_0}\cdot \overline{B_1}\cdot \overline{B_2}\dots \right)\end{array}$$

Under De Morgan’s law, these gates are equivalent (@harrisDigitalDesignComputer2016):