# Kerodon

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

Corollary 3.3.1.10. The forgetful functor

$\{ \textnormal{Simplicial sets} \} \rightarrow \{ \textnormal{Semisimplicial sets} \}$

has a left adjoint, given on objects by the construction $S_{\bullet } \mapsto S_{\bullet }^{+}$.