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Mathlib.Topology.ContinuousMap.Algebra

Algebraic structures over continuous functions #

In this file we define instances of algebraic structures over the type ContinuousMap α β (denoted C(α, β)) of bundled continuous maps from α to β. For example, C(α, β) is a group when β is a group, a ring when β is a ring, etc.

For each type of algebraic structure, we also define an appropriate subobject of α → β with carrier { f : α → β | Continuous f }. For example, when β is a group, a subgroup continuousSubgroup α β of α → β is constructed with carrier { f : α → β | Continuous f }.

Note that, rather than using the derived algebraic structures on these subobjects (for example, when β is a group, the derived group structure on continuousSubgroup α β), one should use C(α, β) with the appropriate instance of the structure.

instance ContinuousFunctions.instCoeFunElemForallSetOfContinuous {α : Type u_1} {β : Type u_2} [TopologicalSpace α] [TopologicalSpace β] :
CoeFun {f : αβ | Continuous f} fun (x : {f : αβ | Continuous f}) => αβ
Equations
  • ContinuousFunctions.instCoeFunElemForallSetOfContinuous = { coe := Subtype.val }

mul and add #

instance ContinuousMap.instMul {α : Type u_1} {β : Type u_2} [TopologicalSpace α] [TopologicalSpace β] [Mul β] [ContinuousMul β] :
Mul C(α, β)
Equations
  • ContinuousMap.instMul = { mul := fun (f g : C(α, β)) => { toFun := f * g, continuous_toFun := } }
instance ContinuousMap.instAdd {α : Type u_1} {β : Type u_2} [TopologicalSpace α] [TopologicalSpace β] [Add β] [ContinuousAdd β] :
Add C(α, β)
Equations
  • ContinuousMap.instAdd = { add := fun (f g : C(α, β)) => { toFun := f + g, continuous_toFun := } }
@[simp]
theorem ContinuousMap.coe_mul {α : Type u_1} {β : Type u_2} [TopologicalSpace α] [TopologicalSpace β] [Mul β] [ContinuousMul β] (f g : C(α, β)) :
(f * g) = f * g
@[simp]
theorem ContinuousMap.coe_add {α : Type u_1} {β : Type u_2} [TopologicalSpace α] [TopologicalSpace β] [Add β] [ContinuousAdd β] (f g : C(α, β)) :
(f + g) = f + g
@[simp]
theorem ContinuousMap.mul_apply {α : Type u_1} {β : Type u_2} [TopologicalSpace α] [TopologicalSpace β] [Mul β] [ContinuousMul β] (f g : C(α, β)) (x : α) :
(f * g) x = f x * g x
@[simp]
theorem ContinuousMap.add_apply {α : Type u_1} {β : Type u_2} [TopologicalSpace α] [TopologicalSpace β] [Add β] [ContinuousAdd β] (f g : C(α, β)) (x : α) :
(f + g) x = f x + g x
@[simp]
theorem ContinuousMap.mul_comp {α : Type u_1} {β : Type u_2} {γ : Type u_3} [TopologicalSpace α] [TopologicalSpace β] [TopologicalSpace γ] [Mul γ] [ContinuousMul γ] (f₁ f₂ : C(β, γ)) (g : C(α, β)) :
(f₁ * f₂).comp g = f₁.comp g * f₂.comp g
@[simp]
theorem ContinuousMap.add_comp {α : Type u_1} {β : Type u_2} {γ : Type u_3} [TopologicalSpace α] [TopologicalSpace β] [TopologicalSpace γ] [Add γ] [ContinuousAdd γ] (f₁ f₂ : C(β, γ)) (g : C(α, β)) :
(f₁ + f₂).comp g = f₁.comp g + f₂.comp g

one #

instance ContinuousMap.instOne {α : Type u_1} {β : Type u_2} [TopologicalSpace α] [TopologicalSpace β] [One β] :
One C(α, β)
Equations
instance ContinuousMap.instZero {α : Type u_1} {β : Type u_2} [TopologicalSpace α] [TopologicalSpace β] [Zero β] :
Zero C(α, β)
Equations
@[simp]
theorem ContinuousMap.coe_one {α : Type u_1} {β : Type u_2} [TopologicalSpace α] [TopologicalSpace β] [One β] :
1 = 1
@[simp]
theorem ContinuousMap.coe_zero {α : Type u_1} {β : Type u_2} [TopologicalSpace α] [TopologicalSpace β] [Zero β] :
0 = 0
@[simp]
theorem ContinuousMap.one_apply {α : Type u_1} {β : Type u_2} [TopologicalSpace α] [TopologicalSpace β] [One β] (x : α) :
1 x = 1
@[simp]
theorem ContinuousMap.zero_apply {α : Type u_1} {β : Type u_2} [TopologicalSpace α] [TopologicalSpace β] [Zero β] (x : α) :
0 x = 0
@[simp]
theorem ContinuousMap.one_comp {α : Type u_1} {β : Type u_2} {γ : Type u_3} [TopologicalSpace α] [TopologicalSpace β] [TopologicalSpace γ] [One γ] (g : C(α, β)) :
@[simp]
theorem ContinuousMap.zero_comp {α : Type u_1} {β : Type u_2} {γ : Type u_3} [TopologicalSpace α] [TopologicalSpace β] [TopologicalSpace γ] [Zero γ] (g : C(α, β)) :

Nat.cast #

instance ContinuousMap.instNatCast {α : Type u_1} {β : Type u_2} [TopologicalSpace α] [TopologicalSpace β] [NatCast β] :
Equations
@[simp]
theorem ContinuousMap.coe_natCast {α : Type u_1} {β : Type u_2} [TopologicalSpace α] [TopologicalSpace β] [NatCast β] (n : ) :
n = n
@[deprecated ContinuousMap.coe_natCast]
theorem ContinuousMap.coe_nat_cast {α : Type u_1} {β : Type u_2} [TopologicalSpace α] [TopologicalSpace β] [NatCast β] (n : ) :
n = n

Alias of ContinuousMap.coe_natCast.

@[simp]
theorem ContinuousMap.natCast_apply {α : Type u_1} {β : Type u_2} [TopologicalSpace α] [TopologicalSpace β] [NatCast β] (n : ) (x : α) :
n x = n
@[deprecated ContinuousMap.natCast_apply]
theorem ContinuousMap.nat_cast_apply {α : Type u_1} {β : Type u_2} [TopologicalSpace α] [TopologicalSpace β] [NatCast β] (n : ) (x : α) :
n x = n

Alias of ContinuousMap.natCast_apply.

Int.cast #

instance ContinuousMap.instIntCast {α : Type u_1} {β : Type u_2} [TopologicalSpace α] [TopologicalSpace β] [IntCast β] :
Equations
@[simp]
theorem ContinuousMap.coe_intCast {α : Type u_1} {β : Type u_2} [TopologicalSpace α] [TopologicalSpace β] [IntCast β] (n : ) :
n = n
@[deprecated ContinuousMap.coe_intCast]
theorem ContinuousMap.coe_int_cast {α : Type u_1} {β : Type u_2} [TopologicalSpace α] [TopologicalSpace β] [IntCast β] (n : ) :
n = n

Alias of ContinuousMap.coe_intCast.

@[simp]
theorem ContinuousMap.intCast_apply {α : Type u_1} {β : Type u_2} [TopologicalSpace α] [TopologicalSpace β] [IntCast β] (n : ) (x : α) :
n x = n
@[deprecated ContinuousMap.intCast_apply]
theorem ContinuousMap.int_cast_apply {α : Type u_1} {β : Type u_2} [TopologicalSpace α] [TopologicalSpace β] [IntCast β] (n : ) (x : α) :
n x = n

Alias of ContinuousMap.intCast_apply.

nsmul and pow #

instance ContinuousMap.instNSMul {α : Type u_1} {β : Type u_2} [TopologicalSpace α] [TopologicalSpace β] [AddMonoid β] [ContinuousAdd β] :
Equations
  • ContinuousMap.instNSMul = { smul := fun (n : ) (f : C(α, β)) => { toFun := n f, continuous_toFun := } }
instance ContinuousMap.instPow {α : Type u_1} {β : Type u_2} [TopologicalSpace α] [TopologicalSpace β] [Monoid β] [ContinuousMul β] :
Pow C(α, β)
Equations
  • ContinuousMap.instPow = { pow := fun (f : C(α, β)) (n : ) => { toFun := f ^ n, continuous_toFun := } }
@[simp]
theorem ContinuousMap.coe_pow {α : Type u_1} {β : Type u_2} [TopologicalSpace α] [TopologicalSpace β] [Monoid β] [ContinuousMul β] (f : C(α, β)) (n : ) :
(f ^ n) = f ^ n
theorem ContinuousMap.coe_nsmul {α : Type u_1} {β : Type u_2} [TopologicalSpace α] [TopologicalSpace β] [AddMonoid β] [ContinuousAdd β] (n : ) (f : C(α, β)) :
(n f) = n f
@[simp]
theorem ContinuousMap.pow_apply {α : Type u_1} {β : Type u_2} [TopologicalSpace α] [TopologicalSpace β] [Monoid β] [ContinuousMul β] (f : C(α, β)) (n : ) (x : α) :
(f ^ n) x = f x ^ n
theorem ContinuousMap.nsmul_apply {α : Type u_1} {β : Type u_2} [TopologicalSpace α] [TopologicalSpace β] [AddMonoid β] [ContinuousAdd β] (f : C(α, β)) (n : ) (x : α) :
(n f) x = n f x
@[simp]
theorem ContinuousMap.pow_comp {α : Type u_1} {β : Type u_2} {γ : Type u_3} [TopologicalSpace α] [TopologicalSpace β] [TopologicalSpace γ] [Monoid γ] [ContinuousMul γ] (f : C(β, γ)) (n : ) (g : C(α, β)) :
(f ^ n).comp g = f.comp g ^ n
theorem ContinuousMap.nsmul_comp {α : Type u_1} {β : Type u_2} {γ : Type u_3} [TopologicalSpace α] [TopologicalSpace β] [TopologicalSpace γ] [AddMonoid γ] [ContinuousAdd γ] (f : C(β, γ)) (n : ) (g : C(α, β)) :
(n f).comp g = n f.comp g

inv and neg #

Equations
  • ContinuousMap.instInvOfContinuousInv = { inv := fun (f : C(α, β)) => { toFun := (⇑f)⁻¹, continuous_toFun := } }
Equations
  • ContinuousMap.instNegOfContinuousNeg = { neg := fun (f : C(α, β)) => { toFun := -f, continuous_toFun := } }
@[simp]
theorem ContinuousMap.coe_inv {α : Type u_1} {β : Type u_2} [TopologicalSpace α] [TopologicalSpace β] [Inv β] [ContinuousInv β] (f : C(α, β)) :
f⁻¹ = (⇑f)⁻¹
@[simp]
theorem ContinuousMap.coe_neg {α : Type u_1} {β : Type u_2} [TopologicalSpace α] [TopologicalSpace β] [Neg β] [ContinuousNeg β] (f : C(α, β)) :
(-f) = -f
@[simp]
theorem ContinuousMap.inv_apply {α : Type u_1} {β : Type u_2} [TopologicalSpace α] [TopologicalSpace β] [Inv β] [ContinuousInv β] (f : C(α, β)) (x : α) :
f⁻¹ x = (f x)⁻¹
@[simp]
theorem ContinuousMap.neg_apply {α : Type u_1} {β : Type u_2} [TopologicalSpace α] [TopologicalSpace β] [Neg β] [ContinuousNeg β] (f : C(α, β)) (x : α) :
(-f) x = -f x
@[simp]
theorem ContinuousMap.inv_comp {α : Type u_1} {β : Type u_2} {γ : Type u_3} [TopologicalSpace α] [TopologicalSpace β] [TopologicalSpace γ] [Inv γ] [ContinuousInv γ] (f : C(β, γ)) (g : C(α, β)) :
f⁻¹.comp g = (f.comp g)⁻¹
@[simp]
theorem ContinuousMap.neg_comp {α : Type u_1} {β : Type u_2} {γ : Type u_3} [TopologicalSpace α] [TopologicalSpace β] [TopologicalSpace γ] [Neg γ] [ContinuousNeg γ] (f : C(β, γ)) (g : C(α, β)) :
(-f).comp g = -f.comp g

div and sub #

Equations
  • ContinuousMap.instDivOfContinuousDiv = { div := fun (f g : C(α, β)) => { toFun := f / g, continuous_toFun := } }
Equations
  • ContinuousMap.instSubOfContinuousSub = { sub := fun (f g : C(α, β)) => { toFun := f - g, continuous_toFun := } }
@[simp]
theorem ContinuousMap.coe_div {α : Type u_1} {β : Type u_2} [TopologicalSpace α] [TopologicalSpace β] [Div β] [ContinuousDiv β] (f g : C(α, β)) :
(f / g) = f / g
@[simp]
theorem ContinuousMap.coe_sub {α : Type u_1} {β : Type u_2} [TopologicalSpace α] [TopologicalSpace β] [Sub β] [ContinuousSub β] (f g : C(α, β)) :
(f - g) = f - g
@[simp]
theorem ContinuousMap.div_apply {α : Type u_1} {β : Type u_2} [TopologicalSpace α] [TopologicalSpace β] [Div β] [ContinuousDiv β] (f g : C(α, β)) (x : α) :
(f / g) x = f x / g x
@[simp]
theorem ContinuousMap.sub_apply {α : Type u_1} {β : Type u_2} [TopologicalSpace α] [TopologicalSpace β] [Sub β] [ContinuousSub β] (f g : C(α, β)) (x : α) :
(f - g) x = f x - g x
@[simp]
theorem ContinuousMap.div_comp {α : Type u_1} {β : Type u_2} {γ : Type u_3} [TopologicalSpace α] [TopologicalSpace β] [TopologicalSpace γ] [Div γ] [ContinuousDiv γ] (f g : C(β, γ)) (h : C(α, β)) :
(f / g).comp h = f.comp h / g.comp h
@[simp]
theorem ContinuousMap.sub_comp {α : Type u_1} {β : Type u_2} {γ : Type u_3} [TopologicalSpace α] [TopologicalSpace β] [TopologicalSpace γ] [Sub γ] [ContinuousSub γ] (f g : C(β, γ)) (h : C(α, β)) :
(f - g).comp h = f.comp h - g.comp h

zpow and zsmul #

Equations
  • ContinuousMap.instZSMul = { smul := fun (z : ) (f : C(α, β)) => { toFun := z f, continuous_toFun := } }
instance ContinuousMap.instZPow {α : Type u_1} {β : Type u_2} [TopologicalSpace α] [TopologicalSpace β] [Group β] [TopologicalGroup β] :
Pow C(α, β)
Equations
  • ContinuousMap.instZPow = { pow := fun (f : C(α, β)) (z : ) => { toFun := f ^ z, continuous_toFun := } }
@[simp]
theorem ContinuousMap.coe_zpow {α : Type u_1} {β : Type u_2} [TopologicalSpace α] [TopologicalSpace β] [Group β] [TopologicalGroup β] (f : C(α, β)) (z : ) :
(f ^ z) = f ^ z
theorem ContinuousMap.coe_zsmul {α : Type u_1} {β : Type u_2} [TopologicalSpace α] [TopologicalSpace β] [AddGroup β] [TopologicalAddGroup β] (z : ) (f : C(α, β)) :
(z f) = z f
@[simp]
theorem ContinuousMap.zpow_apply {α : Type u_1} {β : Type u_2} [TopologicalSpace α] [TopologicalSpace β] [Group β] [TopologicalGroup β] (f : C(α, β)) (z : ) (x : α) :
(f ^ z) x = f x ^ z
theorem ContinuousMap.zsmul_apply {α : Type u_1} {β : Type u_2} [TopologicalSpace α] [TopologicalSpace β] [AddGroup β] [TopologicalAddGroup β] (f : C(α, β)) (z : ) (x : α) :
(z f) x = z f x
@[simp]
theorem ContinuousMap.zpow_comp {α : Type u_1} {β : Type u_2} {γ : Type u_3} [TopologicalSpace α] [TopologicalSpace β] [TopologicalSpace γ] [Group γ] [TopologicalGroup γ] (f : C(β, γ)) (z : ) (g : C(α, β)) :
(f ^ z).comp g = f.comp g ^ z
theorem ContinuousMap.zsmul_comp {α : Type u_1} {β : Type u_2} {γ : Type u_3} [TopologicalSpace α] [TopologicalSpace β] [TopologicalSpace γ] [AddGroup γ] [TopologicalAddGroup γ] (f : C(β, γ)) (z : ) (g : C(α, β)) :
(z f).comp g = z f.comp g

Group structure #

In this section we show that continuous functions valued in a topological group inherit the structure of a group.

def continuousSubmonoid (α : Type u_1) (β : Type u_2) [TopologicalSpace α] [TopologicalSpace β] [MulOneClass β] [ContinuousMul β] :
Submonoid (αβ)

The Submonoid of continuous maps α → β.

Equations
Instances For
    def continuousAddSubmonoid (α : Type u_1) (β : Type u_2) [TopologicalSpace α] [TopologicalSpace β] [AddZeroClass β] [ContinuousAdd β] :
    AddSubmonoid (αβ)

    The AddSubmonoid of continuous maps α → β.

    Equations
    Instances For
      def continuousSubgroup (α : Type u_1) (β : Type u_2) [TopologicalSpace α] [TopologicalSpace β] [Group β] [TopologicalGroup β] :
      Subgroup (αβ)

      The subgroup of continuous maps α → β.

      Equations
      Instances For
        def continuousAddSubgroup (α : Type u_1) (β : Type u_2) [TopologicalSpace α] [TopologicalSpace β] [AddGroup β] [TopologicalAddGroup β] :
        AddSubgroup (αβ)

        The AddSubgroup of continuous maps α → β.

        Equations
        Instances For
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          def ContinuousMap.coeFnMonoidHom {α : Type u_1} {β : Type u_2} [TopologicalSpace α] [TopologicalSpace β] [Monoid β] [ContinuousMul β] :
          C(α, β) →* αβ

          Coercion to a function as a MonoidHom. Similar to MonoidHom.coeFn.

          Equations
          • ContinuousMap.coeFnMonoidHom = { toFun := fun (f : C(α, β)) => f, map_one' := , map_mul' := }
          Instances For
            def ContinuousMap.coeFnAddMonoidHom {α : Type u_1} {β : Type u_2} [TopologicalSpace α] [TopologicalSpace β] [AddMonoid β] [ContinuousAdd β] :
            C(α, β) →+ αβ

            Coercion to a function as an AddMonoidHom. Similar to AddMonoidHom.coeFn.

            Equations
            • ContinuousMap.coeFnAddMonoidHom = { toFun := fun (f : C(α, β)) => f, map_zero' := , map_add' := }
            Instances For
              @[simp]
              theorem ContinuousMap.coeFnAddMonoidHom_apply {α : Type u_1} {β : Type u_2} [TopologicalSpace α] [TopologicalSpace β] [AddMonoid β] [ContinuousAdd β] (f : C(α, β)) (a : α) :
              ContinuousMap.coeFnAddMonoidHom f a = f a
              @[simp]
              theorem ContinuousMap.coeFnMonoidHom_apply {α : Type u_1} {β : Type u_2} [TopologicalSpace α] [TopologicalSpace β] [Monoid β] [ContinuousMul β] (f : C(α, β)) (a : α) :
              ContinuousMap.coeFnMonoidHom f a = f a
              def MonoidHom.compLeftContinuous (α : Type u_1) {β : Type u_2} [TopologicalSpace α] [TopologicalSpace β] {γ : Type u_3} [Monoid β] [ContinuousMul β] [TopologicalSpace γ] [Monoid γ] [ContinuousMul γ] (g : β →* γ) (hg : Continuous g) :
              C(α, β) →* C(α, γ)

              Composition on the left by a (continuous) homomorphism of topological monoids, as a MonoidHom. Similar to MonoidHom.compLeft.

              Equations
              Instances For
                def AddMonoidHom.compLeftContinuous (α : Type u_1) {β : Type u_2} [TopologicalSpace α] [TopologicalSpace β] {γ : Type u_3} [AddMonoid β] [ContinuousAdd β] [TopologicalSpace γ] [AddMonoid γ] [ContinuousAdd γ] (g : β →+ γ) (hg : Continuous g) :
                C(α, β) →+ C(α, γ)

                Composition on the left by a (continuous) homomorphism of topological AddMonoids, as an AddMonoidHom. Similar to AddMonoidHom.comp_left.

                Equations
                Instances For
                  @[simp]
                  theorem AddMonoidHom.compLeftContinuous_apply (α : Type u_1) {β : Type u_2} [TopologicalSpace α] [TopologicalSpace β] {γ : Type u_3} [AddMonoid β] [ContinuousAdd β] [TopologicalSpace γ] [AddMonoid γ] [ContinuousAdd γ] (g : β →+ γ) (hg : Continuous g) (f : C(α, β)) :
                  (AddMonoidHom.compLeftContinuous α g hg) f = { toFun := g, continuous_toFun := hg }.comp f
                  @[simp]
                  theorem MonoidHom.compLeftContinuous_apply (α : Type u_1) {β : Type u_2} [TopologicalSpace α] [TopologicalSpace β] {γ : Type u_3} [Monoid β] [ContinuousMul β] [TopologicalSpace γ] [Monoid γ] [ContinuousMul γ] (g : β →* γ) (hg : Continuous g) (f : C(α, β)) :
                  (MonoidHom.compLeftContinuous α g hg) f = { toFun := g, continuous_toFun := hg }.comp f
                  def ContinuousMap.compMonoidHom' {α : Type u_1} {β : Type u_2} [TopologicalSpace α] [TopologicalSpace β] {γ : Type u_3} [TopologicalSpace γ] [MulOneClass γ] [ContinuousMul γ] (g : C(α, β)) :
                  C(β, γ) →* C(α, γ)

                  Composition on the right as a MonoidHom. Similar to MonoidHom.compHom'.

                  Equations
                  • g.compMonoidHom' = { toFun := fun (f : C(β, γ)) => f.comp g, map_one' := , map_mul' := }
                  Instances For
                    def ContinuousMap.compAddMonoidHom' {α : Type u_1} {β : Type u_2} [TopologicalSpace α] [TopologicalSpace β] {γ : Type u_3} [TopologicalSpace γ] [AddZeroClass γ] [ContinuousAdd γ] (g : C(α, β)) :
                    C(β, γ) →+ C(α, γ)

                    Composition on the right as an AddMonoidHom. Similar to AddMonoidHom.compHom'.

                    Equations
                    • g.compAddMonoidHom' = { toFun := fun (f : C(β, γ)) => f.comp g, map_zero' := , map_add' := }
                    Instances For
                      @[simp]
                      theorem ContinuousMap.compMonoidHom'_apply {α : Type u_1} {β : Type u_2} [TopologicalSpace α] [TopologicalSpace β] {γ : Type u_3} [TopologicalSpace γ] [MulOneClass γ] [ContinuousMul γ] (g : C(α, β)) (f : C(β, γ)) :
                      g.compMonoidHom' f = f.comp g
                      @[simp]
                      theorem ContinuousMap.compAddMonoidHom'_apply {α : Type u_1} {β : Type u_2} [TopologicalSpace α] [TopologicalSpace β] {γ : Type u_3} [TopologicalSpace γ] [AddZeroClass γ] [ContinuousAdd γ] (g : C(α, β)) (f : C(β, γ)) :
                      g.compAddMonoidHom' f = f.comp g
                      @[simp]
                      theorem ContinuousMap.coe_prod {α : Type u_1} {β : Type u_2} [TopologicalSpace α] [TopologicalSpace β] [CommMonoid β] [ContinuousMul β] {ι : Type u_3} (s : Finset ι) (f : ιC(α, β)) :
                      (∏ is, f i) = is, (f i)
                      @[simp]
                      theorem ContinuousMap.coe_sum {α : Type u_1} {β : Type u_2} [TopologicalSpace α] [TopologicalSpace β] [AddCommMonoid β] [ContinuousAdd β] {ι : Type u_3} (s : Finset ι) (f : ιC(α, β)) :
                      (∑ is, f i) = is, (f i)
                      theorem ContinuousMap.prod_apply {α : Type u_1} {β : Type u_2} [TopologicalSpace α] [TopologicalSpace β] [CommMonoid β] [ContinuousMul β] {ι : Type u_3} (s : Finset ι) (f : ιC(α, β)) (a : α) :
                      (∏ is, f i) a = is, (f i) a
                      theorem ContinuousMap.sum_apply {α : Type u_1} {β : Type u_2} [TopologicalSpace α] [TopologicalSpace β] [AddCommMonoid β] [ContinuousAdd β] {ι : Type u_3} (s : Finset ι) (f : ιC(α, β)) (a : α) :
                      (∑ is, f i) a = is, (f i) a
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                      theorem ContinuousMap.hasProd_apply {α : Type u_1} {β : Type u_2} [TopologicalSpace α] [TopologicalSpace β] {γ : Type u_3} [CommMonoid β] [ContinuousMul β] {f : γC(α, β)} {g : C(α, β)} (hf : HasProd f g) (x : α) :
                      HasProd (fun (i : γ) => (f i) x) (g x)

                      If an infinite product of functions in C(α, β) converges to g (for the compact-open topology), then the pointwise product converges to g x for all x ∈ α.

                      theorem ContinuousMap.hasSum_apply {α : Type u_1} {β : Type u_2} [TopologicalSpace α] [TopologicalSpace β] {γ : Type u_3} [AddCommMonoid β] [ContinuousAdd β] {f : γC(α, β)} {g : C(α, β)} (hf : HasSum f g) (x : α) :
                      HasSum (fun (i : γ) => (f i) x) (g x)

                      If an infinite sum of functions in C(α, β) converges to g (for the compact-open topology), then the pointwise sum converges to g x for all x ∈ α.

                      theorem ContinuousMap.multipliable_apply {α : Type u_1} {β : Type u_2} [TopologicalSpace α] [TopologicalSpace β] [CommMonoid β] [ContinuousMul β] {γ : Type u_3} {f : γC(α, β)} (hf : Multipliable f) (x : α) :
                      Multipliable fun (i : γ) => (f i) x
                      theorem ContinuousMap.summable_apply {α : Type u_1} {β : Type u_2} [TopologicalSpace α] [TopologicalSpace β] [AddCommMonoid β] [ContinuousAdd β] {γ : Type u_3} {f : γC(α, β)} (hf : Summable f) (x : α) :
                      Summable fun (i : γ) => (f i) x
                      theorem ContinuousMap.tprod_apply {α : Type u_1} {β : Type u_2} [TopologicalSpace α] [TopologicalSpace β] [T2Space β] [CommMonoid β] [ContinuousMul β] {γ : Type u_3} {f : γC(α, β)} (hf : Multipliable f) (x : α) :
                      ∏' (i : γ), (f i) x = (∏' (i : γ), f i) x
                      theorem ContinuousMap.tsum_apply {α : Type u_1} {β : Type u_2} [TopologicalSpace α] [TopologicalSpace β] [T2Space β] [AddCommMonoid β] [ContinuousAdd β] {γ : Type u_3} {f : γC(α, β)} (hf : Summable f) (x : α) :
                      ∑' (i : γ), (f i) x = (∑' (i : γ), f i) x

                      Ring structure #

                      In this section we show that continuous functions valued in a topological semiring R inherit the structure of a ring.

                      The subsemiring of continuous maps α → β.

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                        def continuousSubring (α : Type u_1) (R : Type u_2) [TopologicalSpace α] [TopologicalSpace R] [Ring R] [TopologicalRing R] :
                        Subring (αR)

                        The subring of continuous maps α → β.

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                          instance ContinuousMap.instRing {α : Type u_1} {β : Type u_2} [TopologicalSpace α] [TopologicalSpace β] [Ring β] [TopologicalRing β] :
                          Ring C(α, β)
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                          def RingHom.compLeftContinuous (α : Type u_1) {β : Type u_2} {γ : Type u_3} [TopologicalSpace α] [TopologicalSpace β] [Semiring β] [TopologicalSemiring β] [TopologicalSpace γ] [Semiring γ] [TopologicalSemiring γ] (g : β →+* γ) (hg : Continuous g) :
                          C(α, β) →+* C(α, γ)

                          Composition on the left by a (continuous) homomorphism of topological semirings, as a RingHom. Similar to RingHom.compLeft.

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                            @[simp]
                            theorem RingHom.compLeftContinuous_apply_apply (α : Type u_1) {β : Type u_2} {γ : Type u_3} [TopologicalSpace α] [TopologicalSpace β] [Semiring β] [TopologicalSemiring β] [TopologicalSpace γ] [Semiring γ] [TopologicalSemiring γ] (g : β →+* γ) (hg : Continuous g) (f : C(α, β)) (a✝ : α) :
                            ((RingHom.compLeftContinuous α g hg) f) a✝ = g (f a✝)
                            def ContinuousMap.coeFnRingHom {α : Type u_1} {β : Type u_2} [TopologicalSpace α] [TopologicalSpace β] [Semiring β] [TopologicalSemiring β] :
                            C(α, β) →+* αβ

                            Coercion to a function as a RingHom.

                            Equations
                            • ContinuousMap.coeFnRingHom = { toMonoidHom := ContinuousMap.coeFnMonoidHom, map_zero' := , map_add' := }
                            Instances For
                              @[simp]
                              theorem ContinuousMap.coeFnRingHom_apply {α : Type u_1} {β : Type u_2} [TopologicalSpace α] [TopologicalSpace β] [Semiring β] [TopologicalSemiring β] (f : C(α, β)) (a : α) :
                              ContinuousMap.coeFnRingHom f a = f a

                              Module structure #

                              In this section we show that continuous functions valued in a topological module M over a topological semiring R inherit the structure of a module.

                              def continuousSubmodule (α : Type u_1) [TopologicalSpace α] (R : Type u_2) [Semiring R] (M : Type u_3) [TopologicalSpace M] [AddCommGroup M] [Module R M] [ContinuousConstSMul R M] [TopologicalAddGroup M] :
                              Submodule R (αM)

                              The R-submodule of continuous maps α → M.

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                                instance ContinuousMap.instSMul {α : Type u_1} [TopologicalSpace α] {R : Type u_3} {M : Type u_5} [TopologicalSpace M] [SMul R M] [ContinuousConstSMul R M] :
                                SMul R C(α, M)
                                Equations
                                • ContinuousMap.instSMul = { smul := fun (r : R) (f : C(α, M)) => { toFun := r f, continuous_toFun := } }
                                instance ContinuousMap.instVAdd {α : Type u_1} [TopologicalSpace α] {R : Type u_3} {M : Type u_5} [TopologicalSpace M] [VAdd R M] [ContinuousConstVAdd R M] :
                                VAdd R C(α, M)
                                Equations
                                • ContinuousMap.instVAdd = { vadd := fun (r : R) (f : C(α, M)) => { toFun := r +ᵥ f, continuous_toFun := } }
                                @[simp]
                                theorem ContinuousMap.coe_smul {α : Type u_1} [TopologicalSpace α] {R : Type u_3} {M : Type u_5} [TopologicalSpace M] [SMul R M] [ContinuousConstSMul R M] (c : R) (f : C(α, M)) :
                                (c f) = c f
                                @[simp]
                                theorem ContinuousMap.coe_vadd {α : Type u_1} [TopologicalSpace α] {R : Type u_3} {M : Type u_5} [TopologicalSpace M] [VAdd R M] [ContinuousConstVAdd R M] (c : R) (f : C(α, M)) :
                                (c +ᵥ f) = c +ᵥ f
                                theorem ContinuousMap.smul_apply {α : Type u_1} [TopologicalSpace α] {R : Type u_3} {M : Type u_5} [TopologicalSpace M] [SMul R M] [ContinuousConstSMul R M] (c : R) (f : C(α, M)) (a : α) :
                                (c f) a = c f a
                                theorem ContinuousMap.vadd_apply {α : Type u_1} [TopologicalSpace α] {R : Type u_3} {M : Type u_5} [TopologicalSpace M] [VAdd R M] [ContinuousConstVAdd R M] (c : R) (f : C(α, M)) (a : α) :
                                (c +ᵥ f) a = c +ᵥ f a
                                @[simp]
                                theorem ContinuousMap.smul_comp {α : Type u_1} {β : Type u_2} [TopologicalSpace α] [TopologicalSpace β] {R : Type u_3} {M : Type u_5} [TopologicalSpace M] [SMul R M] [ContinuousConstSMul R M] (r : R) (f : C(β, M)) (g : C(α, β)) :
                                (r f).comp g = r f.comp g
                                @[simp]
                                theorem ContinuousMap.vadd_comp {α : Type u_1} {β : Type u_2} [TopologicalSpace α] [TopologicalSpace β] {R : Type u_3} {M : Type u_5} [TopologicalSpace M] [VAdd R M] [ContinuousConstVAdd R M] (r : R) (f : C(β, M)) (g : C(α, β)) :
                                (r +ᵥ f).comp g = r +ᵥ f.comp g
                                instance ContinuousMap.instSMulCommClass {α : Type u_1} [TopologicalSpace α] {R : Type u_3} {R₁ : Type u_4} {M : Type u_5} [TopologicalSpace M] [SMul R M] [ContinuousConstSMul R M] [SMul R₁ M] [ContinuousConstSMul R₁ M] [SMulCommClass R R₁ M] :
                                SMulCommClass R R₁ C(α, M)
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                                • =
                                instance ContinuousMap.instVAddCommClass {α : Type u_1} [TopologicalSpace α] {R : Type u_3} {R₁ : Type u_4} {M : Type u_5} [TopologicalSpace M] [VAdd R M] [ContinuousConstVAdd R M] [VAdd R₁ M] [ContinuousConstVAdd R₁ M] [VAddCommClass R R₁ M] :
                                VAddCommClass R R₁ C(α, M)
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                                • =
                                instance ContinuousMap.instIsScalarTower {α : Type u_1} [TopologicalSpace α] {R : Type u_3} {R₁ : Type u_4} {M : Type u_5} [TopologicalSpace M] [SMul R M] [ContinuousConstSMul R M] [SMul R₁ M] [ContinuousConstSMul R₁ M] [SMul R R₁] [IsScalarTower R R₁ M] :
                                IsScalarTower R R₁ C(α, M)
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                                instance ContinuousMap.instIsScalarTower_1 {α : Type u_1} [TopologicalSpace α] {R : Type u_3} {M : Type u_5} [TopologicalSpace M] [SMul R M] [ContinuousConstSMul R M] [Mul M] [ContinuousMul M] [IsScalarTower R M M] :
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                                • =
                                instance ContinuousMap.instSMulCommClass_1 {α : Type u_1} [TopologicalSpace α] {R : Type u_3} {M : Type u_5} [TopologicalSpace M] [SMul R M] [ContinuousConstSMul R M] [Mul M] [ContinuousMul M] [SMulCommClass R M M] :
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                                • =
                                instance ContinuousMap.instSMulCommClass_2 {α : Type u_1} [TopologicalSpace α] {R : Type u_3} {M : Type u_5} [TopologicalSpace M] [SMul R M] [ContinuousConstSMul R M] [Mul M] [ContinuousMul M] [SMulCommClass M R M] :
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                                • =
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                                instance ContinuousMap.module {α : Type u_1} [TopologicalSpace α] {R : Type u_3} {M : Type u_5} [TopologicalSpace M] [Semiring R] [AddCommMonoid M] [ContinuousAdd M] [Module R M] [ContinuousConstSMul R M] :
                                Module R C(α, M)
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                                def ContinuousLinearMap.compLeftContinuous (R : Type u_3) {M : Type u_5} [TopologicalSpace M] {M₂ : Type u_6} [TopologicalSpace M₂] [Semiring R] [AddCommMonoid M] [AddCommMonoid M₂] [ContinuousAdd M] [Module R M] [ContinuousConstSMul R M] [ContinuousAdd M₂] [Module R M₂] [ContinuousConstSMul R M₂] (α : Type u_7) [TopologicalSpace α] (g : M →L[R] M₂) :
                                C(α, M) →ₗ[R] C(α, M₂)

                                Composition on the left by a continuous linear map, as a LinearMap. Similar to LinearMap.compLeft.

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                                  @[simp]
                                  theorem ContinuousLinearMap.compLeftContinuous_apply (R : Type u_3) {M : Type u_5} [TopologicalSpace M] {M₂ : Type u_6} [TopologicalSpace M₂] [Semiring R] [AddCommMonoid M] [AddCommMonoid M₂] [ContinuousAdd M] [Module R M] [ContinuousConstSMul R M] [ContinuousAdd M₂] [Module R M₂] [ContinuousConstSMul R M₂] (α : Type u_7) [TopologicalSpace α] (g : M →L[R] M₂) (a✝ : C(α, M)) :
                                  (ContinuousLinearMap.compLeftContinuous R α g) a✝ = (↑(AddMonoidHom.compLeftContinuous α (↑g).toAddMonoidHom )).toFun a✝

                                  Coercion to a function as a LinearMap.

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                                    @[simp]
                                    theorem ContinuousMap.coeFnLinearMap_apply {α : Type u_1} [TopologicalSpace α] (R : Type u_3) {M : Type u_5} [TopologicalSpace M] [Semiring R] [AddCommMonoid M] [ContinuousAdd M] [Module R M] [ContinuousConstSMul R M] (a✝ : C(α, M)) (a✝¹ : α) :
                                    (ContinuousMap.coeFnLinearMap R) a✝ a✝¹ = (↑ContinuousMap.coeFnAddMonoidHom).toFun a✝ a✝¹

                                    Algebra structure #

                                    In this section we show that continuous functions valued in a topological algebra A over a ring R inherit the structure of an algebra. Note that the hypothesis that A is a topological algebra is obtained by requiring that A be both a ContinuousSMul and a TopologicalSemiring.

                                    def continuousSubalgebra {α : Type u_1} [TopologicalSpace α] {R : Type u_2} [CommSemiring R] {A : Type u_3} [TopologicalSpace A] [Semiring A] [Algebra R A] [TopologicalSemiring A] :
                                    Subalgebra R (αA)

                                    The R-subalgebra of continuous maps α → A.

                                    Equations
                                    • continuousSubalgebra = { carrier := {f : αA | Continuous f}, mul_mem' := , one_mem' := , add_mem' := , zero_mem' := , algebraMap_mem' := }
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                                      def ContinuousMap.C {α : Type u_1} [TopologicalSpace α] {R : Type u_2} [CommSemiring R] {A : Type u_3} [TopologicalSpace A] [Semiring A] [Algebra R A] [TopologicalSemiring A] :
                                      R →+* C(α, A)

                                      Continuous constant functions as a RingHom.

                                      Equations
                                      • ContinuousMap.C = { toFun := fun (c : R) => { toFun := fun (x : α) => (algebraMap R A) c, continuous_toFun := }, map_one' := , map_mul' := , map_zero' := , map_add' := }
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                                        @[simp]
                                        theorem ContinuousMap.C_apply {α : Type u_1} [TopologicalSpace α] {R : Type u_2} [CommSemiring R] {A : Type u_3} [TopologicalSpace A] [Semiring A] [Algebra R A] [TopologicalSemiring A] (r : R) (a : α) :
                                        (ContinuousMap.C r) a = (algebraMap R A) r
                                        instance ContinuousMap.algebra {α : Type u_1} [TopologicalSpace α] {R : Type u_2} [CommSemiring R] {A : Type u_3} [TopologicalSpace A] [Semiring A] [Algebra R A] [TopologicalSemiring A] :
                                        Equations
                                        • ContinuousMap.algebra = Algebra.mk ContinuousMap.C
                                        def AlgHom.compLeftContinuous (R : Type u_2) [CommSemiring R] {A : Type u_3} [TopologicalSpace A] [Semiring A] [Algebra R A] [TopologicalSemiring A] {A₂ : Type u_4} [TopologicalSpace A₂] [Semiring A₂] [Algebra R A₂] [TopologicalSemiring A₂] {α : Type u_5} [TopologicalSpace α] (g : A →ₐ[R] A₂) (hg : Continuous g) :
                                        C(α, A) →ₐ[R] C(α, A₂)

                                        Composition on the left by a (continuous) homomorphism of topological R-algebras, as an AlgHom. Similar to AlgHom.compLeft.

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                                          @[simp]
                                          theorem AlgHom.compLeftContinuous_apply_apply (R : Type u_2) [CommSemiring R] {A : Type u_3} [TopologicalSpace A] [Semiring A] [Algebra R A] [TopologicalSemiring A] {A₂ : Type u_4} [TopologicalSpace A₂] [Semiring A₂] [Algebra R A₂] [TopologicalSemiring A₂] {α : Type u_5} [TopologicalSpace α] (g : A →ₐ[R] A₂) (hg : Continuous g) (f : C(α, A)) (a✝ : α) :
                                          ((AlgHom.compLeftContinuous R g hg) f) a✝ = g (f a✝)
                                          def ContinuousMap.compRightAlgHom (R : Type u_2) [CommSemiring R] (A : Type u_3) [TopologicalSpace A] [Semiring A] [Algebra R A] [TopologicalSemiring A] {α : Type u_5} {β : Type u_6} [TopologicalSpace α] [TopologicalSpace β] (f : C(α, β)) :
                                          C(β, A) →ₐ[R] C(α, A)

                                          Precomposition of functions into a topological semiring by a continuous map is an algebra homomorphism.

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                                            @[simp]
                                            theorem ContinuousMap.compRightAlgHom_apply (R : Type u_2) [CommSemiring R] (A : Type u_3) [TopologicalSpace A] [Semiring A] [Algebra R A] [TopologicalSemiring A] {α : Type u_5} {β : Type u_6} [TopologicalSpace α] [TopologicalSpace β] (f : C(α, β)) (g : C(β, A)) :
                                            (ContinuousMap.compRightAlgHom R A f) g = g.comp f
                                            def ContinuousMap.coeFnAlgHom {α : Type u_1} [TopologicalSpace α] (R : Type u_2) [CommSemiring R] {A : Type u_3} [TopologicalSpace A] [Semiring A] [Algebra R A] [TopologicalSemiring A] :
                                            C(α, A) →ₐ[R] αA

                                            Coercion to a function as an AlgHom.

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                                              @[simp]
                                              theorem ContinuousMap.coeFnAlgHom_apply {α : Type u_1} [TopologicalSpace α] (R : Type u_2) [CommSemiring R] {A : Type u_3} [TopologicalSpace A] [Semiring A] [Algebra R A] [TopologicalSemiring A] (f : C(α, A)) (a : α) :
                                              @[reducible, inline]
                                              abbrev Subalgebra.SeparatesPoints {α : Type u_1} [TopologicalSpace α] {R : Type u_2} [CommSemiring R] {A : Type u_3} [TopologicalSpace A] [Semiring A] [Algebra R A] [TopologicalSemiring A] (s : Subalgebra R C(α, A)) :

                                              A version of Set.SeparatesPoints for subalgebras of the continuous functions, used for stating the Stone-Weierstrass theorem.

                                              Equations
                                              • s.SeparatesPoints = ((fun (f : C(α, A)) => f) '' s).SeparatesPoints
                                              Instances For
                                                theorem Subalgebra.separatesPoints_monotone {α : Type u_1} [TopologicalSpace α] {R : Type u_2} [CommSemiring R] {A : Type u_3} [TopologicalSpace A] [Semiring A] [Algebra R A] [TopologicalSemiring A] :
                                                Monotone fun (s : Subalgebra R C(α, A)) => s.SeparatesPoints
                                                @[simp]
                                                theorem algebraMap_apply {α : Type u_1} [TopologicalSpace α] {R : Type u_2} [CommSemiring R] {A : Type u_3} [TopologicalSpace A] [Semiring A] [Algebra R A] [TopologicalSemiring A] (k : R) (a : α) :
                                                ((algebraMap R C(α, A)) k) a = k 1
                                                def Set.SeparatesPointsStrongly {α : Type u_1} [TopologicalSpace α] {𝕜 : Type u_5} [TopologicalSpace 𝕜] (s : Set C(α, 𝕜)) :

                                                A set of continuous maps "separates points strongly" if for each pair of distinct points there is a function with specified values on them.

                                                We give a slightly unusual formulation, where the specified values are given by some function v, and we ask f x = v x ∧ f y = v y. This avoids needing a hypothesis x ≠ y.

                                                In fact, this definition would work perfectly well for a set of non-continuous functions, but as the only current use case is in the Stone-Weierstrass theorem, writing it this way avoids having to deal with casts inside the set. (This may need to change if we do Stone-Weierstrass on non-compact spaces, where the functions would be continuous functions vanishing at infinity.)

                                                Equations
                                                • s.SeparatesPointsStrongly = ∀ (v : α𝕜) (x y : α), fs, f x = v x f y = v y
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                                                  theorem Subalgebra.SeparatesPoints.strongly {α : Type u_1} [TopologicalSpace α] {𝕜 : Type u_5} [TopologicalSpace 𝕜] [Field 𝕜] [TopologicalRing 𝕜] {s : Subalgebra 𝕜 C(α, 𝕜)} (h : s.SeparatesPoints) :
                                                  (↑s).SeparatesPointsStrongly

                                                  Working in continuous functions into a topological field, a subalgebra of functions that separates points also separates points strongly.

                                                  By the hypothesis, we can find a function f so f x ≠ f y. By an affine transformation in the field we can arrange so that f x = a and f x = b.

                                                  Structure as module over scalar functions #

                                                  If M is a module over R, then we show that the space of continuous functions from α to M is naturally a module over the ring of continuous functions from α to R.

                                                  instance ContinuousMap.instSMul' {α : Type u_1} [TopologicalSpace α] {R : Type u_2} [Semiring R] [TopologicalSpace R] {M : Type u_3} [TopologicalSpace M] [AddCommMonoid M] [Module R M] [ContinuousSMul R M] :
                                                  SMul C(α, R) C(α, M)
                                                  Equations
                                                  • ContinuousMap.instSMul' = { smul := fun (f : C(α, R)) (g : C(α, M)) => { toFun := fun (x : α) => f x g x, continuous_toFun := } }
                                                  @[simp]
                                                  theorem ContinuousMap.coe_smul' {α : Type u_1} [TopologicalSpace α] {R : Type u_2} [Semiring R] [TopologicalSpace R] {M : Type u_3} [TopologicalSpace M] [AddCommMonoid M] [Module R M] [ContinuousSMul R M] (f : C(α, R)) (g : C(α, M)) :
                                                  (f g) = f g

                                                  Coercion to a function for a scalar-valued continuous map multiplying a vector-valued one (as opposed to ContinuousMap.coe_smul which is multiplication by a constant scalar).

                                                  theorem ContinuousMap.smul_apply' {α : Type u_1} [TopologicalSpace α] {R : Type u_2} [Semiring R] [TopologicalSpace R] {M : Type u_3} [TopologicalSpace M] [AddCommMonoid M] [Module R M] [ContinuousSMul R M] (f : C(α, R)) (g : C(α, M)) (x : α) :
                                                  (f g) x = f x g x

                                                  Evaluation of a scalar-valued continuous map multiplying a vector-valued one (as opposed to ContinuousMap.smul_apply which is multiplication by a constant scalar).

                                                  Equations

                                                  Evaluation as a bundled map #

                                                  Evaluation of continuous maps at a point, bundled as an algebra homomorphism.

                                                  Equations
                                                  • ContinuousMap.evalAlgHom S R x = { toFun := fun (f : C(X, R)) => f x, map_one' := , map_mul' := , map_zero' := , map_add' := , commutes' := }
                                                  Instances For
                                                    @[simp]
                                                    theorem ContinuousMap.evalAlgHom_apply {X : Type u_1} (S : Type u_2) (R : Type u_3) [TopologicalSpace X] [CommSemiring S] [CommSemiring R] [Algebra S R] [TopologicalSpace R] [TopologicalSemiring R] (x : X) (f : C(X, R)) :