Documentation

Mathlib.Algebra.Group.Action.End

Interaction between actions and endomorphisms/automorphisms #

This file provides two things:

Tags #

monoid action, group action

Tautological actions #

Tautological action by Function.End #

The tautological additive action by Additive (Function.End α) on α.

Equations
    @[simp]
    theorem Function.End.smul_def {α : Type u_5} (f : Function.End α) (a : α) :
    f a = f a
    theorem Function.End.mul_def {α : Type u_5} (f g : Function.End α) :
    f * g = f g

    Tautological action by Equiv.Perm #

    instance Equiv.Perm.applyMulAction (α : Type u_6) :
    MulAction (Perm α) α

    The tautological action by Equiv.Perm α on α.

    This generalizes Function.End.applyMulAction.

    Equations
      @[simp]
      theorem Equiv.Perm.smul_def {α : Type u_6} (f : Perm α) (a : α) :
      f a = f a

      The permutation group of α acts transitively on α.

      Tautological action by MulAut #

      instance MulAut.applyMulAction {M : Type u_2} [Monoid M] :

      The tautological action by MulAut M on M.

      Equations

        The tautological action by MulAut M on M.

        This generalizes Function.End.applyMulAction.

        Equations
          @[simp]
          theorem MulAut.smul_def {M : Type u_2} [Monoid M] (f : MulAut M) (a : M) :
          f a = f a

          MulAut.applyDistribMulAction is faithful.

          Tautological action by AddAut #

          instance AddAut.applyMulAction {M : Type u_2} [AddMonoid M] :

          The tautological action by AddAut M on M.

          Equations
            @[simp]
            theorem AddAut.smul_def {M : Type u_2} [AddMonoid M] (f : AddAut M) (a : M) :
            f a = f a

            Converting actions to and from homs to the monoid/group of endomorphisms/automorphisms #

            def MulAction.toEndHom {M : Type u_2} {α : Type u_5} [Monoid M] [MulAction M α] :

            The monoid hom representing a monoid action.

            When M is a group, see MulAction.toPermHom.

            Equations
              Instances For
                @[reducible, inline]
                abbrev MulAction.ofEndHom {M : Type u_2} {α : Type u_5} [Monoid M] (f : M →* Function.End α) :

                The monoid action induced by a monoid hom to Function.End α

                See note [reducible non-instances].

                Equations
                  Instances For
                    def AddAction.toEndHom {M : Type u_2} {α : Type u_5} [AddMonoid M] [AddAction M α] :

                    The additive monoid hom representing an additive monoid action.

                    When M is a group, see AddAction.toPermHom.

                    Equations
                      Instances For
                        @[reducible, inline]
                        abbrev AddAction.ofEndHom {M : Type u_2} {α : Type u_5} [AddMonoid M] (f : M →+ Additive (Function.End α)) :

                        The additive action induced by a hom to Additive (Function.End α)

                        See note [reducible non-instances].

                        Equations
                          Instances For
                            def MulAction.toPermHom (G : Type u_1) (α : Type u_5) [Group G] [MulAction G α] :

                            Given an action of a group G on a set α, each g : G defines a permutation of α.

                            Equations
                              Instances For
                                @[simp]
                                theorem MulAction.toPermHom_apply (G : Type u_1) (α : Type u_5) [Group G] [MulAction G α] (a : G) :
                                (toPermHom G α) a = toPerm a
                                theorem MulAction.coe_toPermHom (G : Type u_1) (α : Type u_5) [Group G] [MulAction G α] :
                                (toPermHom G α) = toPerm
                                theorem MulAction.toPerm_one (G : Type u_1) (α : Type u_5) [Group G] [MulAction G α] :
                                toPerm 1 = 1
                                def AddAction.toPermHom (G : Type u_1) (α : Type u_5) [AddGroup G] [AddAction G α] :

                                Given an action of an additive group G on a set α, each g : G defines a permutation of α.

                                Equations
                                  Instances For
                                    @[simp]
                                    theorem AddAction.toPermHom_apply_apply (G : Type u_1) (α : Type u_5) [AddGroup G] [AddAction G α] (a : G) (x : α) :
                                    ((toPermHom G α) a) x = a +ᵥ x
                                    @[simp]
                                    theorem AddAction.toPermHom_apply_symm_apply (G : Type u_1) (α : Type u_5) [AddGroup G] [AddAction G α] (a : G) (x : α) :
                                    theorem AddAction.coe_toPermHom (G : Type u_1) (α : Type u_5) [AddGroup G] [AddAction G α] :
                                    (toPermHom G α) = toPerm
                                    theorem AddAction.toPerm_zero (G : Type u_1) (α : Type u_5) [AddGroup G] [AddAction G α] :
                                    toPerm 0 = 1
                                    def MulDistribMulAction.toMulEquiv {G : Type u_1} (M : Type u_2) [Group G] [Monoid M] [MulDistribMulAction G M] (x : G) :
                                    M ≃* M

                                    Each element of the group defines a multiplicative monoid isomorphism.

                                    This is a stronger version of MulAction.toPerm.

                                    Equations
                                      Instances For
                                        @[simp]
                                        theorem MulDistribMulAction.toMulEquiv_apply {G : Type u_1} (M : Type u_2) [Group G] [Monoid M] [MulDistribMulAction G M] (x : G) (a✝ : M) :
                                        (toMulEquiv M x) a✝ = x a✝
                                        @[simp]
                                        theorem MulDistribMulAction.toMulEquiv_symm_apply {G : Type u_1} (M : Type u_2) [Group G] [Monoid M] [MulDistribMulAction G M] (x : G) (a✝ : M) :
                                        (toMulEquiv M x).symm a✝ = x⁻¹ a✝

                                        Each element of the group defines a multiplicative monoid isomorphism.

                                        This is a stronger version of MulAction.toPermHom.

                                        Equations
                                          Instances For
                                            @[simp]
                                            theorem MulDistribMulAction.toMulAut_apply (G : Type u_1) (M : Type u_2) [Group G] [Monoid M] [MulDistribMulAction G M] (x : G) :
                                            (toMulAut G M) x = toMulEquiv M x
                                            def mulAutArrow {G : Type u_1} {M : Type u_2} {A : Type u_4} [Group G] [MulAction G A] [Monoid M] :
                                            G →* MulAut (AM)

                                            Given groups G H with G acting on A, G acts by multiplicative automorphisms on A → H.

                                            Equations
                                              Instances For
                                                @[simp]
                                                theorem mulAutArrow_apply_symm_apply {G : Type u_1} {M : Type u_2} {A : Type u_4} [Group G] [MulAction G A] [Monoid M] (x : G) (a✝ : AM) (a✝¹ : A) :
                                                (MulEquiv.symm (mulAutArrow x)) a✝ a✝¹ = (x⁻¹ a✝) a✝¹
                                                @[simp]
                                                theorem mulAutArrow_apply_apply {G : Type u_1} {M : Type u_2} {A : Type u_4} [Group G] [MulAction G A] [Monoid M] (x : G) (a✝ : AM) (a✝¹ : A) :
                                                (mulAutArrow x) a✝ a✝¹ = (x a✝) a✝¹