Theorem: NumberField.ComplexEmbedding.exists_comp_symm_eq_of_comp_eq
File: Mathlib/NumberTheory/NumberField/Embeddings.lean

Proof steps:
state_before: K : Type u_1
inst✝³ : Field K
k : Type u_2
inst✝² : Field k
inst✝¹ : Algebra k K
inst✝ : IsGalois k K
φ ψ : K →+* ℂ
h : φ.comp (algebraMap k K) = ψ.comp (algebraMap k K)
⊢ ∃ σ, φ.comp ↑σ.symm = ψ
state_after: K : Type u_1
inst✝³ : Field K
k : Type u_2
inst✝² : Field k
inst✝¹ : Algebra k K
inst✝ : IsGalois k K
φ ψ : K →+* ℂ
h : φ.comp (algebraMap k K) = ψ.comp (algebraMap k K)
this : Algebra k ℂ := (φ.comp (algebraMap k K)).toAlgebra
⊢ ∃ σ, φ.comp ↑σ.symm = ψ
tactic: letI := (φ.comp (algebraMap k K)).toAlgebra
state_before: K : Type u_1
inst✝³ : Field K
k : Type u_2
inst✝² : Field k
inst✝¹ : Algebra k K
inst✝ : IsGalois k K
φ ψ : K →+* ℂ
h : φ.comp (algebraMap k K) = ψ.comp (algebraMap k K)
this : Algebra k ℂ := (φ.comp (algebraMap k K)).toAlgebra
⊢ ∃ σ, φ.comp ↑σ.symm = ψ
state_after: K : Type u_1
inst✝³ : Field K
k : Type u_2
inst✝² : Field k
inst✝¹ : Algebra k K
inst✝ : IsGalois k K
φ ψ : K →+* ℂ
h : φ.comp (algebraMap k K) = ψ.comp (algebraMap k K)
this✝ : Algebra k ℂ := (φ.comp (algebraMap k K)).toAlgebra
this : Algebra K ℂ := φ.toAlgebra
⊢ ∃ σ, φ.comp ↑σ.symm = ψ
tactic: letI := φ.toAlgebra
state_before: K : Type u_1
inst✝³ : Field K
k : Type u_2
inst✝² : Field k
inst✝¹ : Algebra k K
inst✝ : IsGalois k K
φ ψ : K →+* ℂ
h : φ.comp (algebraMap k K) = ψ.comp (algebraMap k K)
this✝ : Algebra k ℂ := (φ.comp (algebraMap k K)).toAlgebra
this : Algebra K ℂ := φ.toAlgebra
⊢ ∃ σ, φ.comp ↑σ.symm = ψ
state_after: K : Type u_1
inst✝³ : Field K
k : Type u_2
inst✝² : Field k
inst✝¹ : Algebra k K
inst✝ : IsGalois k K
φ ψ : K →+* ℂ
h : φ.comp (algebraMap k K) = ψ.comp (algebraMap k K)
this✝¹ : Algebra k ℂ := (φ.comp (algebraMap k K)).toAlgebra
this✝ : Algebra K ℂ := φ.toAlgebra
this : IsScalarTower k K ℂ
⊢ ∃ σ, φ.comp ↑σ.symm = ψ
tactic: have : IsScalarTower k K ℂ := IsScalarTower.of_algebraMap_eq' rfl
state_before: K : Type u_1
inst✝³ : Field K
k : Type u_2
inst✝² : Field k
inst✝¹ : Algebra k K
inst✝ : IsGalois k K
φ ψ : K →+* ℂ
h : φ.comp (algebraMap k K) = ψ.comp (algebraMap k K)
this✝¹ : Algebra k ℂ := (φ.comp (algebraMap k K)).toAlgebra
this✝ : Algebra K ℂ := φ.toAlgebra
this : IsScalarTower k K ℂ
⊢ ∃ σ, φ.comp ↑σ.symm = ψ
state_after: K : Type u_1
inst✝³ : Field K
k : Type u_2
inst✝² : Field k
inst✝¹ : Algebra k K
inst✝ : IsGalois k K
φ ψ : K →+* ℂ
h : φ.comp (algebraMap k K) = ψ.comp (algebraMap k K)
this✝¹ : Algebra k ℂ := (φ.comp (algebraMap k K)).toAlgebra
this✝ : Algebra K ℂ := φ.toAlgebra
this : IsScalarTower k K ℂ
ψ' : K →ₐ[k] ℂ := { toRingHom := ψ, commutes' := ⋯ }
⊢ ∃ σ, φ.comp ↑σ.symm = ψ
tactic: let ψ' : K →ₐ[k] ℂ := { ψ with commutes' := fun r ↦ (RingHom.congr_fun h r).symm }
state_before: K : Type u_1
inst✝³ : Field K
k : Type u_2
inst✝² : Field k
inst✝¹ : Algebra k K
inst✝ : IsGalois k K
φ ψ : K →+* ℂ
h : φ.comp (algebraMap k K) = ψ.comp (algebraMap k K)
this✝¹ : Algebra k ℂ := (φ.comp (algebraMap k K)).toAlgebra
this✝ : Algebra K ℂ := φ.toAlgebra
this : IsScalarTower k K ℂ
ψ' : K →ₐ[k] ℂ := { toRingHom := ψ, commutes' := ⋯ }
⊢ ∃ σ, φ.comp ↑σ.symm = ψ
state_after: case h
K : Type u_1
inst✝³ : Field K
k : Type u_2
inst✝² : Field k
inst✝¹ : Algebra k K
inst✝ : IsGalois k K
φ ψ : K →+* ℂ
h : φ.comp (algebraMap k K) = ψ.comp (algebraMap k K)
this✝¹ : Algebra k ℂ := (φ.comp (algebraMap k K)).toAlgebra
this✝ : Algebra K ℂ := φ.toAlgebra
this : IsScalarTower k K ℂ
ψ' : K →ₐ[k] ℂ := { toRingHom := ψ, commutes' := ⋯ }
⊢ φ.comp ↑(ψ'.restrictNormal' K).symm.symm = ψ
tactic: use (AlgHom.restrictNormal' ψ' K).symm
state_before: case h
K : Type u_1
inst✝³ : Field K
k : Type u_2
inst✝² : Field k
inst✝¹ : Algebra k K
inst✝ : IsGalois k K
φ ψ : K →+* ℂ
h : φ.comp (algebraMap k K) = ψ.comp (algebraMap k K)
this✝¹ : Algebra k ℂ := (φ.comp (algebraMap k K)).toAlgebra
this✝ : Algebra K ℂ := φ.toAlgebra
this : IsScalarTower k K ℂ
ψ' : K →ₐ[k] ℂ := { toRingHom := ψ, commutes' := ⋯ }
⊢ φ.comp ↑(ψ'.restrictNormal' K).symm.symm = ψ
state_after: case h.a
K : Type u_1
inst✝³ : Field K
k : Type u_2
inst✝² : Field k
inst✝¹ : Algebra k K
inst✝ : IsGalois k K
φ ψ : K →+* ℂ
h : φ.comp (algebraMap k K) = ψ.comp (algebraMap k K)
this✝¹ : Algebra k ℂ := (φ.comp (algebraMap k K)).toAlgebra
this✝ : Algebra K ℂ := φ.toAlgebra
this : IsScalarTower k K ℂ
ψ' : K →ₐ[k] ℂ := { toRingHom := ψ, commutes' := ⋯ }
x : K
⊢ (φ.comp ↑(ψ'.restrictNormal' K).symm.symm) x = ψ x
tactic: ext1 x
state_before: case h.a
K : Type u_1
inst✝³ : Field K
k : Type u_2
inst✝² : Field k
inst✝¹ : Algebra k K
inst✝ : IsGalois k K
φ ψ : K →+* ℂ
h : φ.comp (algebraMap k K) = ψ.comp (algebraMap k K)
this✝¹ : Algebra k ℂ := (φ.comp (algebraMap k K)).toAlgebra
this✝ : Algebra K ℂ := φ.toAlgebra
this : IsScalarTower k K ℂ
ψ' : K →ₐ[k] ℂ := { toRingHom := ψ, commutes' := ⋯ }
x : K
⊢ (φ.comp ↑(ψ'.restrictNormal' K).symm.symm) x = ψ x
state_after: no goals
tactic: exact AlgHom.restrictNormal_commutes ψ' K x