Union with Empty Set

Theorem
The union of any set with the empty set is the set itself:


 * $S \cup \varnothing = S$

Proof 2
From Empty Set Subset of All, $\varnothing \subseteq S$.

From Union with Superset is Superset‎ it follows that $S \cup \varnothing = S$.

Also see

 * Intersection with Null