$\Newextarrow{\xhookrightarrow}{10,10}{0x21AA}$
8.57
\begin{equation} \begin{gathered}\label{equation:density-via-Yoneda2} \xymatrix@R =50pt@C=50pt{ & \mathscr {G} \circ F^{\operatorname{op}} \ar [dr]^{\alpha } & \\ h_{Y} \circ F^{\operatorname{op}} \ar [rr]^{ \operatorname{id}} \ar [ur]^{\beta } & & h_{Y}^{\circ } } \end{gathered} \end{equation}