Documentation

Mathlib.CategoryTheory.Monoidal.Grp_

The category of groups in a cartesian monoidal category #

We define group objects in cartesian monoidal categories.

We show that the associativity diagram of a group object is always cartesian and deduce that morphisms of group objects commute with taking inverses.

We show that a finite-product-preserving functor takes group objects to group objects.

A group object internal to a cartesian monoidal category. Also see the bundled Grp_.

Instances

    The inverse in a group object

    Equations
    Instances For

      The inverse in a group object

      Equations
      • One or more equations did not get rendered due to their size.
      Instances For

        A group object in a cartesian monoidal category.

        Instances For

          The trivial group object.

          Equations
          Instances For

            Make a group object from Grp_Class.

            Equations
            Instances For
              Equations

              The map (· * f).

              Equations
              • One or more equations did not get rendered due to their size.
              Instances For

                The associativity diagram of a group object is cartesian.

                In fact, any monoid object whose associativity diagram is cartesian can be made into a group object (we do not prove this in this file), so we should expect that many properties of group objects follow from this result.

                The forgetful functor from group objects to the ambient category.

                Equations
                Instances For
                  @[simp]
                  theorem Grp_.forget_map (C : Type u₁) [CategoryTheory.Category.{v₁, u₁} C] [CategoryTheory.CartesianMonoidalCategory C] {X✝ Y✝ : Grp_ C} (f : X✝ Y✝) :
                  (forget C).map f = f.hom

                  Constructor for isomorphisms in the category Grp_ C.

                  Equations
                  Instances For

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

                    Equations
                    • One or more equations did not get rendered due to their size.
                    Instances For
                      @[simp]
                      theorem CategoryTheory.Functor.mapGrp_map_hom {C : Type u₁} [Category.{v₁, u₁} C] [CartesianMonoidalCategory C] {D : Type u₂} [Category.{v₂, u₂} D] [CartesianMonoidalCategory D] (F : Functor C D) [F.Monoidal] {X✝ Y✝ : Grp_ C} (f : X✝ Y✝) :
                      (F.mapGrp.map f).hom = F.map f.hom

                      The identity functor is also the identity on group objects.

                      Equations
                      Instances For

                        The composition functor is also the composition on group objects.

                        Equations
                        Instances For

                          Natural transformations between functors lift to group objects.

                          Equations
                          Instances For

                            Natural isomorphisms between functors lift to group objects.

                            Equations
                            Instances For

                              mapGrp is functorial in the left-exact functor.

                              Equations
                              • One or more equations did not get rendered due to their size.
                              Instances For

                                An adjunction of monoidal functors lifts to an adjunction of their lifts to group objects.

                                Equations
                                • One or more equations did not get rendered due to their size.
                                Instances For

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

                                  Equations
                                  • One or more equations did not get rendered due to their size.
                                  Instances For