# Kerodon

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Variant 6.3.3.7. Let $\operatorname{\mathcal{C}}$ be an $\infty$-category, let $W$ be a collection of morphisms of $\operatorname{\mathcal{C}}$ which is colocalizing, and let $\operatorname{\mathcal{C}}'$ denote the full subcategory of $\operatorname{\mathcal{C}}$ spanned by the $W$-colocal objects. Then:

$(1)$

The full subcategory $\operatorname{\mathcal{C}}' \subseteq \operatorname{\mathcal{C}}$ is coreflective.

$(2)$

Let $L: \operatorname{\mathcal{C}}\rightarrow \operatorname{\mathcal{C}}'$ be a right adjoint to the inclusion functor $\iota : \operatorname{\mathcal{C}}' \hookrightarrow \operatorname{\mathcal{C}}$. Then $L$ exhibits $\operatorname{\mathcal{C}}'$ as a localization of $\operatorname{\mathcal{C}}$ with respect to $W$.

$(3)$

A morphism $f: X \rightarrow Y$ of $\operatorname{\mathcal{C}}$ belongs to $W$ if and only if $L(f)$ is an isomorphism in the $\infty$-category $\operatorname{\mathcal{C}}'$.