# Kerodon

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

Example 3.4.2.7. Suppose we are given a pushout diagram of simplicial sets

3.48
$$\label{diagram:homotopy-pushout-square9} \begin{gathered} \xymatrix { A \ar [r]^{f} \ar [d] & B \ar [d] \\ C \ar [r] & D. } \end{gathered}$$

If $f$ is a monomorphism, then (3.48) is also a homotopy pushout diagram.