ThmDex – An index of mathematical definitions, results, and conjectures.
Result R1744 on D17: Finite set
Finite union of finite sets is finite
Formulation 0
Let $E_1, \dots, E_N$ each be a D17: Finite set such that
(i) $\bigcup_{n = 1}^N E_n$ is the D77: Set union of $E_1, \dots, E_N$
Then $\bigcup_{n = 1}^N E_n$ is a D17: Finite set.