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

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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