$\Newextarrow{\xhookrightarrow}{10,10}{0x21AA}$
10.3
\begin{equation} \begin{gathered}\label{equation:maps-into-constant-simplicial-easy} \xymatrix@R =50pt@C=50pt{ X_{n} \ar [d]^{ \alpha ^{\ast } } \ar [r]^-{ \iota ^{\ast }_{n} } & X_{0} \ar [d]^{ \epsilon } \\ X_{m} \ar [r]^-{ \epsilon \circ \iota ^{\ast }_{m} } & Y } \end{gathered} \end{equation}