De Morgan's Laws (Set Theory)/Set Complement/Complement of Union/Venn Diagram
Jump to navigation
Jump to search
Theorem
- $\overline {T_1 \cup T_2} = \overline T_1 \cap \overline T_2$
Proof
Demonstration by Venn diagram:
$\overline T_1$ is depicted in yellow and $\overline T_2$ is depicted in red.
Their intersection, $\overline T_1 \cap \overline T_2$, is depicted in orange.
As can be seen by inspection, this also equals the complement of the union of $T_1$ and $T_2$.
Sources
- 2008: David Joyner: Adventures in Group Theory (2nd ed.) ... (previous) ... (next): Chapter $1$: Elementary, my dear Watson: $\S 1.2$: Elements, my dear Watson: Ponderable $1.2.1 \ \text{(d)}$