Expanding upon Remark 2.5.1.1.2, we may think of the characteristic function

\[ \chi _{x}\colon X\to \{ \mathsf{t},\mathsf{f}\} \]

of an element $x$ of $X$ as a decategorification of the representable presheaf and of the representable copresheaf

\begin{align*} h_{X} & \colon \mathcal{C}^{\mathsf{op}} \to \mathsf{Sets},\\ h^{X} & \colon \mathcal{C} \to \mathsf{Sets}\end{align*}

associated of an object $X$ of a category $\mathcal{C}$.


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