ThmDex – An index of mathematical definitions, results, and conjectures.
Formulation F10015 on D17: Finite set
F10015
Formulation 0
Let $\mathbb{N}$ be the D225: Set of natural numbers.
A D11: Set $X$ is a finite set if and only if \begin{equation} \exists \, N \in \mathbb{N} : \text{Bij}(\{ 1, \ldots, N \} \to X) \neq \emptyset \end{equation}