Let $X$ be a D11: Set.
Let $f : X \to \{ \{ x \} : x \in X \}$ be a D18: Map such that

(i)	\begin{equation} f(x) : = \{ x \} \end{equation}

Then $f$ is a D468: Bijective map from $X$ to $\{ \{ x \} : x \in X \}$.