Kerodon

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

Example 1.1.2.12. The horns $\Lambda ^{1}_{0}$ and $\Lambda ^{1}_{1}$ are both isomorphic to $\Delta ^0$, and the inclusion maps $\Lambda ^{1}_{0} \hookrightarrow \operatorname{\partial \Delta }^1 \hookleftarrow \Lambda ^{1}_{1}$ induce an isomorphism $\Delta ^{0} \amalg \Delta ^{0} \simeq \operatorname{\partial \Delta }^1$.