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Mathlib.CategoryTheory.Monoidal.CommGrp_

The category of commutative groups in a Cartesian monoidal category #

A commutative group object internal to a Cartesian monoidal category.

  • X : C

    The underlying object in the ambient monoidal category

  • grp : GrpObj self.X
  • comm : IsCommMonObj self.X
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    @[deprecated CategoryTheory.CommGrp (since := "2025-10-13")]

    Alias of CategoryTheory.CommGrp.


    A commutative group object internal to a Cartesian monoidal category.

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      @[reducible, inline]

      A commutative group object is a group object.

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        @[deprecated CategoryTheory.CommGrp.toGrp (since := "2025-10-13")]

        Alias of CategoryTheory.CommGrp.toGrp.


        A commutative group object is a group object.

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          A commutative group object is a commutative monoid object.

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            @[deprecated CategoryTheory.CommGrp.toCommMon (since := "2025-09-15")]

            Alias of CategoryTheory.CommGrp.toCommMon.


            A commutative group object is a commutative monoid object.

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              @[reducible, inline]

              A commutative group object is a monoid object.

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                @[deprecated CategoryTheory.CommGrp.toMon (since := "2025-09-15")]

                Alias of CategoryTheory.CommGrp.toMon.


                A commutative group object is a monoid object.

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                  @[simp]
                  theorem CategoryTheory.CommGrp.comp' {C : Type u₁} [Category.{v₁, u₁} C] [CartesianMonoidalCategory C] [BraidedCategory C] {A₁ A₂ A₃ : CommGrp C} (f : A₁ A₂) (g : A₂ A₃) :
                  @[deprecated CategoryTheory.CommGrp.forget₂Grp (since := "2025-10-13")]

                  Alias of CategoryTheory.CommGrp.forget₂Grp.


                  The forgetful functor from commutative group objects to group objects.

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                    @[deprecated CategoryTheory.CommGrp.fullyFaithfulForget₂Grp (since := "2025-10-13")]

                    Alias of CategoryTheory.CommGrp.fullyFaithfulForget₂Grp.


                    The forgetful functor from commutative group objects to group objects is fully faithful.

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                      @[deprecated CategoryTheory.CommGrp.forget₂CommMon (since := "2025-09-15")]

                      Alias of CategoryTheory.CommGrp.forget₂CommMon.


                      The forgetful functor from commutative group objects to commutative monoid objects.

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                        @[deprecated CategoryTheory.CommGrp.fullyFaithfulForget₂CommMon (since := "2025-09-15")]

                        Alias of CategoryTheory.CommGrp.fullyFaithfulForget₂CommMon.


                        The forgetful functor from commutative group objects to commutative monoid objects is fully faithful.

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                          The forgetful functor from commutative group objects to the ambient category.

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                            @[simp]
                            theorem CategoryTheory.CommGrp.forget_map (C : Type u₁) [Category.{v₁, u₁} C] [CartesianMonoidalCategory C] [BraidedCategory C] {X✝ Y✝ : CommGrp C} (f : X✝ Y✝) :
                            (forget C).map f = f.hom
                            def CategoryTheory.CommGrp.mkIso' {C : Type u₁} [Category.{v₁, u₁} C] [CartesianMonoidalCategory C] [BraidedCategory C] {G H : C} (e : G H) [GrpObj G] [IsCommMonObj G] [GrpObj H] [IsCommMonObj H] [IsMonHom e.hom] :
                            { X := G, grp := inst✝, comm := inst✝¹ } { X := H, grp := inst✝², comm := inst✝³ }

                            Construct an isomorphism of commutative group objects by giving a monoid isomorphism between the underlying objects.

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                              @[reducible, inline]

                              Construct an isomorphism of group objects by giving an isomorphism between the underlying objects and checking compatibility with unit and multiplication only in the forward direction.

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                                A finite-product-preserving functor takes commutative group objects to commutative group objects.

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                                  If F : C ⥤ D is a fully faithful monoidal functor, then CommGrpCat(F) : CommGrpCat C ⥤ CommGrpCat D is fully faithful too.

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                                    The identity functor is also the identity on commutative group objects.

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                                      The composition functor is also the composition on commutative group objects.

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                                        Natural transformations between functors lift to commutative group objects.

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                                          Natural isomorphisms between functors lift to commutative group objects.

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                                            mapCommGrp is functorial in the left-exact functor.

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                                              An adjunction of braided functors lifts to an adjunction of their lifts to commutative group objects.

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                                                An equivalence of categories lifts to an equivalence of their commutative group objects.

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