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Mathlib.CategoryTheory.Enriched.Ordinary

Enriched ordinary categories #

If V is a monoidal category, a V-enriched category C does not need to be a category. However, when we have both Category C and EnrichedCategory V C, we may require that the type of morphisms X ⟶ Y in C identify to 𝟙_ V ⟶ EnrichedCategory.Hom X Y. This data shall be packaged in the typeclass EnrichedOrdinaryCategory V C.

In particular, if C is a V-enriched category, it is shown that the "underlying" category ForgetEnrichment V C is equipped with a EnrichedOrdinaryCategory V C instance.

Simplicial categories are implemented in AlgebraicTopology.SimplicialCategory.Basic using an abbreviation for EnrichedOrdinaryCategory SSet C.

An enriched ordinary category is a category C that is also enriched over a category V in such a way that morphisms X ⟶ Y in C identify to morphisms 𝟙_ V ⟶ (X ⟶[V] Y) in V.

Instances

    The bijection (X ⟶ Y) ≃ (𝟙_ V ⟶ (X ⟶[V] Y)) given by a EnrichedOrdinaryCategory instance.

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      The morphism (X' ⟶[V] Y) ⟶ (X ⟶[V] Y) induced by a morphism X ⟶ X'.

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        The morphism (X ⟶[V] Y) ⟶ (X ⟶[V] Y') induced by a morphism Y ⟶ Y'.

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          Given an isomorphism α : Y ≅ Y₁ in C, the enriched composition map eComp V X Y Z : (X ⟶[V] Y) ⊗ (Y ⟶[V] Z) ⟶ (X ⟶[V] Z) factors through the V object (X ⟶[V] Y₁) ⊗ (Y₁ ⟶[V] Z) via the map defined by whiskering in the middle with α.hom and α.inv.

          The bifunctor Cᵒᵖ ⥤ C ⥤ V which sends X : Cᵒᵖ and Y : C to X ⟶[V] Y.

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