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Mathlib.CategoryTheory.Action.Monoidal

Induced monoidal structure on Action V G #

We show:

Given an object X isomorphic to the tensor unit of V, X equipped with the trivial action is isomorphic to the tensor unit of Action V G.

Instances For
    @[implicit_reducible]

    When V is braided the forgetful functor Action V G to V is braided.

    @[implicit_reducible]

    Upgrading the functor Action V G ⥤ (SingleObj G ⥤ V) to a monoidal functor.

    @[implicit_reducible]

    Upgrading the functor (SingleObj G ⥤ V) ⥤ Action V G to a monoidal functor.

    The natural isomorphism of G-sets Gⁿ⁺¹ ≅ G × Gⁿ, where G acts by left multiplication on each factor.

    Instances For
      @[simp]
      theorem Action.diagonalSuccIsoTensorDiagonal_hom_hom (G : Type u) [Monoid G] (n : ) (a✝ : (diagonal G (n + 1)).V) :
      (diagonalSuccIsoTensorDiagonal G n).hom.hom a✝ = (a✝ 0, Fin.tail a✝)

      Given X : Action (Type u) G for G a group, then G × X (with G acting as left multiplication on the first factor and by X.ρ on the second) is isomorphic as a G-set to G × X (with G acting as left multiplication on the first factor and trivially on the second). The isomorphism is given by (g, x) ↦ (g, g⁻¹ • x).

      Instances For
        @[simp]
        theorem Action.leftRegularTensorIso_inv_hom (G : Type u) [Group G] (X : Action (Type u) G) (a✝ : (CategoryTheory.MonoidalCategoryStruct.tensorObj (leftRegular G) (trivial G X.V)).V) :
        (leftRegularTensorIso G X).inv.hom a✝ = (a✝.1, X.ρ a✝.1 a✝.2)
        noncomputable def Action.diagonalSuccIsoTensorTrivial (G : Type u) [Group G] (n : ) :

        An isomorphism of G-sets Gⁿ⁺¹ ≅ G × Gⁿ, where G acts by left multiplication on Gⁿ⁺¹ and G but trivially on Gⁿ. The map sends (g₀, ..., gₙ) ↦ (g₀, (g₀⁻¹g₁, g₁⁻¹g₂, ..., gₙ₋₁⁻¹gₙ)), and the inverse is (g₀, (g₁, ..., gₙ)) ↦ (g₀, g₀g₁, g₀g₁g₂, ..., g₀g₁...gₙ).

        Instances For
          @[simp]
          theorem Action.diagonalSuccIsoTensorTrivial_hom_hom_apply {G : Type u} [Group G] {n : } (f : Fin (n + 1)G) :
          (diagonalSuccIsoTensorTrivial G n).hom.hom f = (f 0, fun (i : Fin n) => (f i.castSucc)⁻¹ * f i.succ)
          @[simp]
          theorem Action.diagonalSuccIsoTensorTrivial_inv_hom_apply {G : Type u} [Group G] {n : } (g : G) (f : Fin nG) :
          @[implicit_reducible]

          A lax monoidal functor induces a lax monoidal functor between the categories of G-actions within those categories.

          @[implicit_reducible]

          An oplax monoidal functor induces an oplax monoidal functor between the categories of G-actions within those categories.

          @[implicit_reducible]

          A monoidal functor induces a monoidal functor between the categories of G-actions within those categories.