ThmDex – An index of mathematical definitions, results, and conjectures.

Result R2082 on D77: Set union
Subresult of R4268: Finite set union with empty set

Binary set union with empty set

Formulation 0

Let $X$ be a D11: Set.
Let $\emptyset$ be the D13: Empty set.

Then \begin{equation} X \cup \emptyset = \emptyset \cup X = X \end{equation}

Also known as

Binary set-theoretic disjunction with set-theoretic falsity