Warning 8.5.9.14. The category $\mathrm{Dy}_{+}$ of Notation 8.5.9.12 is not a groupoid. In fact, every isomorphism in the category $\mathrm{Dy}_{+}$ is an identity morphism.
$\Newextarrow{\xhookrightarrow}{10,10}{0x21AA}$
Warning 8.5.9.14. The category $\mathrm{Dy}_{+}$ of Notation 8.5.9.12 is not a groupoid. In fact, every isomorphism in the category $\mathrm{Dy}_{+}$ is an identity morphism.