Kerodon

$\Newextarrow{\xRightarrow}{5,5}{0x21D2}$ $\newcommand\empty{}$
$\Newextarrow{\xhookrightarrow}{10,10}{0x21AA}$

Remark 4.3.3.17. Let $i: X \hookrightarrow X'$ and $j: Y \hookrightarrow Y'$ be monomorphisms of simplicial sets. From the description of Remark 4.3.3.15, we see that the join $(i \star j): X \star Y \rightarrow X' \star Y'$ is also a monomorphism of simplicial sets.