# Kerodon

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Example 5.3.3.13. Let $f: X \rightarrow Y$ be a morphism of simplicial sets, which we identify with a functor $\mathscr {F}: [1] \rightarrow \operatorname{Set_{\Delta }}$ (so that $X = \mathscr {F}(0)$ and $Y = \mathscr {F}(1)$). Then Example 5.3.3.12 supplies an isomorphism of simplicial sets $\operatorname{N}_{\bullet }^{\mathscr {F}}([1]) \simeq X \star _{Y} Y$.