CatDat

Implication Details

Claim: If a category is finitely accessible, then it has filtered-colimit-stable monomorphisms.

Proof: Let C\C be a finitely accessible category and let GG be a set of finitely presentable objects which generates C\C under filtered colimits. Consider GG as a full subcategory and consider the restricted Yoneda embedding C[Gop,Set]\C \hookrightarrow [G^{\op},\Set]. It preserves filtered colimits (essentially by the definition of a finitely presentable object) and all limits, in particular monomorphisms. It also reflects monomorphisms since GG is a generating set. Therefore, since Set\Set and hence the functor category has filtered-colimit-stable monomorphisms, this is also true for C\C.

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