(1) | \begin{equation} \forall \, x \in X : f(x) = x \end{equation} | (D440: Identity map) |
(2) | \begin{equation} X = Y \end{equation} |
(1) | \begin{equation} \forall \, x \in X : f(x) = x \end{equation} | (D440: Identity map) |
(2) | \begin{equation} X = Y \end{equation} |