Let $X$ be a D11: Set such that

(i)	$\mathcal{P}(X)$ is the D80: Power set of $X$

Let $f : X \to \mathcal{P}(X)$ be a D18: Map such that

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

Then $f$ is an D467: Injective map from $X$ to $Y$.