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Mathlib.Topology.ContinuousMap.Units

Units of continuous functions #

This file concerns itself with C(X, M)ˣ and C(X, Mˣ) when X is a topological space and M has some monoid structure compatible with its topology.

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def ContinuousMap.unitsLift {X : Type u_1} {M : Type u_2} [TopologicalSpace X] [Monoid M] [TopologicalSpace M] [ContinuousMul M] :
C(X, Mˣ) ≃ C(X, M)ˣ

Equivalence between continuous maps into the units of a monoid with continuous multiplication and the units of the monoid of continuous maps.

Instances For
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    def ContinuousMap.addUnitsLift {X : Type u_1} {M : Type u_2} [TopologicalSpace X] [AddMonoid M] [TopologicalSpace M] [ContinuousAdd M] :
    C(X, AddUnits M) ≃ AddUnits C(X, M)

    Equivalence between continuous maps into the additive units of an additive monoid with continuous addition and the additive units of the additive monoid of continuous maps.

    Instances For
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      @[simp]
      theorem ContinuousMap.val_addUnitsLift_symm_apply_apply {X : Type u_1} {M : Type u_2} [TopologicalSpace X] [AddMonoid M] [TopologicalSpace M] [ContinuousAdd M] (f : AddUnits C(X, M)) (x : X) :
      ↑((addUnitsLift.symm f) x) = ↑f x
      source
      @[simp]
      theorem ContinuousMap.val_addUnitsLift_apply_apply {X : Type u_1} {M : Type u_2} [TopologicalSpace X] [AddMonoid M] [TopologicalSpace M] [ContinuousAdd M] (f : C(X, AddUnits M)) (x : X) :
      ↑(addUnitsLift f) x = ↑(f x)
      source
      @[simp]
      theorem ContinuousMap.val_unitsLift_symm_apply_apply {X : Type u_1} {M : Type u_2} [TopologicalSpace X] [Monoid M] [TopologicalSpace M] [ContinuousMul M] (f : C(X, M)ˣ) (x : X) :
      ↑((unitsLift.symm f) x) = ↑f x
      source
      @[simp]
      theorem ContinuousMap.val_unitsLift_apply_apply {X : Type u_1} {M : Type u_2} [TopologicalSpace X] [Monoid M] [TopologicalSpace M] [ContinuousMul M] (f : C(X, Mˣ)) (x : X) :
      ↑(unitsLift f) x = ↑(f x)
      source
      @[simp]
      theorem ContinuousMap.unitsLift_apply_inv_apply {X : Type u_1} {M : Type u_2} [TopologicalSpace X] [Monoid M] [TopologicalSpace M] [ContinuousMul M] (f : C(X, Mˣ)) (x : X) :
      ↑(unitsLift f)⁻¹ x = ↑(f x)⁻¹
      source
      @[simp]
      theorem ContinuousMap.addUnitsLift_apply_neg_apply {X : Type u_1} {M : Type u_2} [TopologicalSpace X] [AddMonoid M] [TopologicalSpace M] [ContinuousAdd M] (f : C(X, AddUnits M)) (x : X) :
      ↑(-addUnitsLift f) x = ↑(-f x)
      source
      @[simp]
      theorem ContinuousMap.unitsLift_symm_apply_apply_inv' {X : Type u_1} {M : Type u_2} [TopologicalSpace X] [Monoid M] [TopologicalSpace M] [ContinuousMul M] (f : C(X, M)ˣ) (x : X) :
      ↑((unitsLift.symm f) x)⁻¹ = ↑f⁻¹ x
      source
      @[simp]
      theorem ContinuousMap.addUnitsLift_symm_apply_apply_neg' {X : Type u_1} {M : Type u_2} [TopologicalSpace X] [AddMonoid M] [TopologicalSpace M] [ContinuousAdd M] (f : AddUnits C(X, M)) (x : X) :
      ↑(-(addUnitsLift.symm f) x) = ↑(-f) x
      source
      theorem ContinuousMap.continuous_isUnit_unit {X : Type u_1} {R : Type u_3} [TopologicalSpace X] [NormedRing R] [CompleteSpace R] {f : C(X, R)} (h : ∀ (x : X), IsUnit (f x)) :
      Continuous fun (x : X) => ⋯.unit
      source
      noncomputable def ContinuousMap.unitsOfForallIsUnit {X : Type u_1} {R : Type u_3} [TopologicalSpace X] [NormedRing R] [CompleteSpace R] {f : C(X, R)} (h : ∀ (x : X), IsUnit (f x)) :
      C(X, Rˣ)

      Construct a continuous map into the group of units of a normed ring from a function into the normed ring and a proof that every element of the range is a unit.

      Instances For
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        @[simp]
        theorem ContinuousMap.unitsOfForallIsUnit_apply {X : Type u_1} {R : Type u_3} [TopologicalSpace X] [NormedRing R] [CompleteSpace R] {f : C(X, R)} (h : ∀ (x : X), IsUnit (f x)) (x : X) :
        (unitsOfForallIsUnit h) x = ⋯.unit
        source
        instance ContinuousMap.canLift {X : Type u_1} {R : Type u_3} [TopologicalSpace X] [NormedRing R] [CompleteSpace R] :
        CanLift C(X, R) C(X, Rˣ) (fun (f : C(X, Rˣ)) => { toFun := fun (x : X) => ↑(f x), continuous_toFun := ⋯ }) fun (f : C(X, R)) => ∀ (x : X), IsUnit (f x)
        source
        theorem ContinuousMap.isUnit_iff_forall_isUnit {X : Type u_1} {R : Type u_3} [TopologicalSpace X] [NormedRing R] [CompleteSpace R] (f : C(X, R)) :
        IsUnit f ↔ ∀ (x : X), IsUnit (f x)
        source
        theorem ContinuousMap.isUnit_iff_forall_ne_zero {X : Type u_1} {R : Type u_3} [TopologicalSpace X] [NormedDivisionRing R] [CompleteSpace R] (f : C(X, R)) :
        IsUnit f ↔ ∀ (x : X), f x ≠ 0
        source
        theorem ContinuousMap.spectrum_eq_preimage_range {X : Type u_1} {R : Type u_3} {𝕜 : Type u_4} [TopologicalSpace X] [NormedField 𝕜] [NormedDivisionRing R] [Algebra 𝕜 R] [CompleteSpace R] (f : C(X, R)) :
        spectrum 𝕜 f = ⇑(algebraMap 𝕜 R) ⁻¹' Set.range ⇑f
        source
        theorem ContinuousMap.spectrum_eq_range {X : Type u_1} {𝕜 : Type u_4} [TopologicalSpace X] [NormedField 𝕜] [CompleteSpace 𝕜] (f : C(X, 𝕜)) :
        spectrum 𝕜 f = Set.range ⇑f