Module: Mathlib.Topology.Instances.Complex

Goal state before:
pp: case e'_2
K : Subfield ℂ
ψ : ↥K →+* ℂ
hc : UniformContinuous ⇑ψ
this✝¹ : IsTopologicalDivisionRing ℂ :=
  { toIsTopologicalRing := NormedDivisionRing.to_isTopologicalDivisionRing.toIsTopologicalRing,
    toContinuousInv₀ := NormedDivisionRing.to_isTopologicalDivisionRing.toContinuousInv₀ }
this✝ : IsTopologicalRing ↥K.topologicalClosure := Subring.instIsTopologicalRing K.topologicalClosure.toSubring
ι : ↥K → ↥K.topologicalClosure := ⇑(Subfield.inclusion ⋯)
ui : IsUniformInducing ι
di : IsDenseInducing ι := IsUniformInducing.isDenseInducing ui ?refine_1
extψ : ↥K.topologicalClosure →+* ℂ := IsDenseInducing.extendRingHom ui ⋯ hc
hψ : Continuous (⋯.extend ⇑ψ)
h : K.topologicalClosure = ofRealHom.fieldRange
j : ↥K.topologicalClosure ≃+* ↥ofRealHom.fieldRange := RingEquiv.subfieldCongr h
ψ₁ : ℝ →+* ℂ := extψ.comp (j.symm.toRingHom.comp ofRealHom.rangeRestrictField)
hψ₁ : Continuous ⇑ψ₁
x : ↥K
r : ℝ
hr : ofRealHom.rangeRestrictField r = j (ι x)
this : extψ (↑j.symm (j (ι x))) = ofRealHom r
⊢ (↑↑ψ).toFun x = extψ (↑j.symm (j (ι x)))

pp: case e'_3
K : Subfield ℂ
ψ : ↥K →+* ℂ
hc : UniformContinuous ⇑ψ
this✝¹ : IsTopologicalDivisionRing ℂ :=
  { toIsTopologicalRing := NormedDivisionRing.to_isTopologicalDivisionRing.toIsTopologicalRing,
    toContinuousInv₀ := NormedDivisionRing.to_isTopologicalDivisionRing.toContinuousInv₀ }
this✝ : IsTopologicalRing ↥K.topologicalClosure := Subring.instIsTopologicalRing K.topologicalClosure.toSubring
ι : ↥K → ↥K.topologicalClosure := ⇑(Subfield.inclusion ⋯)
ui : IsUniformInducing ι
di : IsDenseInducing ι := IsUniformInducing.isDenseInducing ui ?refine_1
extψ : ↥K.topologicalClosure →+* ℂ := IsDenseInducing.extendRingHom ui ⋯ hc
hψ : Continuous (⋯.extend ⇑ψ)
h : K.topologicalClosure = ofRealHom.fieldRange
j : ↥K.topologicalClosure ≃+* ↥ofRealHom.fieldRange := RingEquiv.subfieldCongr h
ψ₁ : ℝ →+* ℂ := extψ.comp (j.symm.toRingHom.comp ofRealHom.rangeRestrictField)
hψ₁ : Continuous ⇑ψ₁
x : ↥K
r : ℝ
hr : ofRealHom.rangeRestrictField r = j (ι x)
this : extψ (↑j.symm (j (ι x))) = ofRealHom r
⊢ K.subtype x = ofRealHom r

Tactic:
· exact (IsDenseInducing.extend_eq di hc.continuous _).symm

Goal state after:
case e'_3
K : Subfield ℂ
ψ : ↥K →+* ℂ
hc : UniformContinuous ⇑ψ
this✝¹ : IsTopologicalDivisionRing ℂ :=
  { toIsTopologicalRing := NormedDivisionRing.to_isTopologicalDivisionRing.toIsTopologicalRing,
    toContinuousInv₀ := NormedDivisionRing.to_isTopologicalDivisionRing.toContinuousInv₀ }
this✝ : IsTopologicalRing ↥K.topologicalClosure := Subring.instIsTopologicalRing K.topologicalClosure.toSubring
ι : ↥K → ↥K.topologicalClosure := ⇑(Subfield.inclusion ⋯)
ui : IsUniformInducing ι
di : IsDenseInducing ι := IsUniformInducing.isDenseInducing ui ?refine_1
extψ : ↥K.topologicalClosure →+* ℂ := IsDenseInducing.extendRingHom ui ⋯ hc
hψ : Continuous (⋯.extend ⇑ψ)
h : K.topologicalClosure = ofRealHom.fieldRange
j : ↥K.topologicalClosure ≃+* ↥ofRealHom.fieldRange := RingEquiv.subfieldCongr h
ψ₁ : ℝ →+* ℂ := extψ.comp (j.symm.toRingHom.comp ofRealHom.rangeRestrictField)
hψ₁ : Continuous ⇑ψ₁
x : ↥K
r : ℝ
hr : ofRealHom.rangeRestrictField r = j (ι x)
this : extψ (↑j.symm (j (ι x))) = ofRealHom r
⊢ K.subtype x = ofRealHom r