Remark 3.4.2.4. Let $f_0: A \rightarrow A_0$ and $f_1: A \rightarrow A_1$ be morphisms of simplicial sets. Then we have a canonical isomorphism $( A_0 {\coprod }_{A}^{\mathrm{h}} A_1 )^{\operatorname{op}} \simeq A_{1}^{\operatorname{op}} {\coprod }^{\mathrm{h}}_{A^{\operatorname{op}}} A_{0}^{\operatorname{op}}$.
$\Newextarrow{\xhookrightarrow}{10,10}{0x21AA}$