Exercise 8.1.2.8. Let $f: K \rightarrow \operatorname{\mathcal{C}}$ be a morphism of simplicial sets. Show that the coslice inclusion $\operatorname{\mathcal{C}}_{f/} \rightarrow \operatorname{Fun}_{ / \operatorname{\mathcal{C}}^{\operatorname{op}} }( K^{\operatorname{op}}, \operatorname{Tw}(\operatorname{\mathcal{C}}) )$ of Construction 8.1.2.7 is a monomorphism of simplicial sets (as suggested by our terminology).
$\Newextarrow{\xhookrightarrow}{10,10}{0x21AA}$