awhecmu/canonical-drafter-extract-mathlib huggingface dataset:
-- Lean 4 proof step from Mathlib.FieldTheory.PrimitiveElement (goal)
Goal:
F : Type u_1
inst : Field F
inst_1 : Infinite F
E : Type u_2
inst_2 : Field E
α β : E
inst_3 : Algebra F E
inst_4 : Algebra.IsSeparable F E
hα : IsIntegral F α
hβ : IsIntegral F β
f : F[X] := minpoly F α
g : F[X] := minpoly F β
ιFE : F →+* E := algebraMap F E
ιEE' : E →+* (Polynomial.map ιFE g).SplittingField := algebraMap E (Polynomial.map ιFE g).SplittingField
c : F
hc :
  ∀ α' ∈ (Polynomial.map (ιEE'.comp ιFE) f).roots,
    ∀ β' ∈ (Polynomial.map (ιEE'.comp ιFE) g).roots,
      -HSub.hSub (β := (Polynomial.map ιFE g).SplittingField) α'
              ((ιEE' : (a : E) → (Polynomial.map ιFE g).SplittingField) α : (Polynomial.map ιFE g).SplittingField) /
          HSub.hSub (β := (Polynomial.map ιFE g).SplittingField) β'
            ((ιEE' : (a : E) → (Polynomial.map ιFE g).SplittingField) β : (Polynomial.map ιFE g).SplittingField) ≠
        (ιEE'.comp ιFE : (a : F) → (Polynomial.map ιFE g).SplittingField) c
γ : E := α + c • β
⊢ ∃ (γ : E), Eq (α := IntermediateField F E) F⟮α, β⟯ F⟮γ⟯
have suffices : Membership.mem (γ := IntermediateField F E) F⟮γ⟯ β
Tactic: suffices β_in_Fγ : β ∈ F⟮γ⟯ by
    use γ
    apply le_antisymm
    · rw [adjoin_le_iff]
      have α_in_Fγ : α ∈ F⟮γ⟯ := by
        rw [← add_sub_cancel_right α (c • β)]
        exact F⟮γ⟯.sub_mem (mem_adjoin_simple_self F γ) (F⟮γ⟯.toSubalgebra.smul_mem β_in_Fγ c)
      rintro x (rfl | rfl) <;> assumption
    · rw [adjoin_simple_le_iff]
      have α_in_Fαβ : α ∈ F⟮α, β⟯ := subset_adjoin F {α, β} (Set.mem_insert α {β})
      have β_in_Fαβ : β ∈ F⟮α, β⟯ := subset_adjoin F {α, β} (Set.mem_insert_of_mem α rfl)
      exact F⟮α, β⟯.add_mem α_in_Fαβ (F⟮α, β⟯.smul_mem β_in_Fαβ)
-- Lean 4 proof step from Mathlib.FieldTheory.PrimitiveElement (hypothesis)
Goal:
F : Type u_1
inst : Field F
inst_1 : Infinite F
E : Type u_2
inst_2 : Field E
α β : E
inst_3 : Algebra F E
inst_4 : Algebra.IsSeparable F E
hα : IsIntegral F α
hβ : IsIntegral F β
f : F[X] := minpoly F α
g : F[X] := minpoly F β
ιFE : F →+* E := algebraMap F E
ιEE' : E →+* (Polynomial.map ιFE g).SplittingField := algebraMap E (Polynomial.map ιFE g).SplittingField
c : F
hc :
  ∀ α' ∈ (Polynomial.map (ιEE'.comp ιFE) f).roots,
    ∀ β' ∈ (Polynomial.map (ιEE'.comp ιFE) g).roots,
      -HSub.hSub (β := (Polynomial.map ιFE g).SplittingField) α'
              ((ιEE' : (a : E) → (Polynomial.map ιFE g).SplittingField) α : (Polynomial.map ιFE g).SplittingField) /
          HSub.hSub (β := (Polynomial.map ιFE g).SplittingField) β'
            ((ιEE' : (a : E) → (Polynomial.map ιFE g).SplittingField) β : (Polynomial.map ιFE g).SplittingField) ≠
        (ιEE'.comp ιFE : (a : F) → (Polynomial.map ιFE g).SplittingField) c
γ : E := α + c • β
p : (↥F⟮γ⟯)[X] :=
  EuclideanDomain.gcd
    (comp (Polynomial.map (algebraMap F ↥F⟮γ⟯) f)
      (HSub.hSub (α := (↥F⟮γ⟯)[X]) ((C : (a : ↥F⟮γ⟯) → (↥F⟮γ⟯)[X]) (AdjoinSimple.gen F γ) : (↥F⟮γ⟯)[X])
        (HMul.hMul (α := (↥F⟮γ⟯)[X]) (β := (↥F⟮γ⟯)[X])
          ((C : (a : ↥F⟮γ⟯) → (↥F⟮γ⟯)[X])
              (Subtype.mk (p := fun (x : E) ↦ Membership.mem (γ := IntermediateField F E) F⟮γ⟯ x)
                ((algebraMap F E : (a : F) → E) c) ⋯) :
            (↥F⟮γ⟯)[X])
          X)))
    (Polynomial.map (algebraMap F ↥F⟮γ⟯) g)
h : E[X] :=
  EuclideanDomain.gcd
    ((Polynomial.map ιFE f).comp
      (HSub.hSub (α := E[X]) ((C : (a : E) → E[X]) γ : E[X])
        (HMul.hMul (α := E[X]) (β := E[X]) ((C : (a : E) → E[X]) ((ιFE : (a : F) → E) c) : E[X]) X)))
    (Polynomial.map ιFE g)
⊢ Membership.mem (γ := IntermediateField F E) F⟮γ⟯ β
have map_g_ne_zero : Polynomial.map ιFE g ≠ 0
Tactic: have map_g_ne_zero : g.map ιFE ≠ 0 := map_ne_zero (minpoly.ne_zero hβ)
-- Lean 4 proof step from Mathlib.FieldTheory.PrimitiveElement (hypothesis)
Goal:
F : Type u_1
inst : Field F
inst_1 : Infinite F
E : Type u_2
inst_2 : Field E
α β : E
inst_3 : Algebra F E
inst_4 : Algebra.IsSeparable F E
hα : IsIntegral F α
hβ : IsIntegral F β
f : F[X] := minpoly F α
g : F[X] := minpoly F β
ιFE : F →+* E := algebraMap F E
ιEE' : E →+* (Polynomial.map ιFE g).SplittingField := algebraMap E (Polynomial.map ιFE g).SplittingField
c : F
hc :
  ∀ α' ∈ (Polynomial.map (ιEE'.comp ιFE) f).roots,
    ∀ β' ∈ (Polynomial.map (ιEE'.comp ιFE) g).roots,
      -HSub.hSub (β := (Polynomial.map ιFE g).SplittingField) α'
              ((ιEE' : (a : E) → (Polynomial.map ιFE g).SplittingField) α : (Polynomial.map ιFE g).SplittingField) /
          HSub.hSub (β := (Polynomial.map ιFE g).SplittingField) β'
            ((ιEE' : (a : E) → (Polynomial.map ιFE g).SplittingField) β : (Polynomial.map ιFE g).SplittingField) ≠
        (ιEE'.comp ιFE : (a : F) → (Polynomial.map ιFE g).SplittingField) c
γ : E := α + c • β
p : (↥F⟮γ⟯)[X] :=
  EuclideanDomain.gcd
    (comp (Polynomial.map (algebraMap F ↥F⟮γ⟯) f)
      (HSub.hSub (α := (↥F⟮γ⟯)[X]) ((C : (a : ↥F⟮γ⟯) → (↥F⟮γ⟯)[X]) (AdjoinSimple.gen F γ) : (↥F⟮γ⟯)[X])
        (HMul.hMul (α := (↥F⟮γ⟯)[X]) (β := (↥F⟮γ⟯)[X])
          ((C : (a : ↥F⟮γ⟯) → (↥F⟮γ⟯)[X])
              (Subtype.mk (p := fun (x : E) ↦ Membership.mem (γ := IntermediateField F E) F⟮γ⟯ x)
                ((algebraMap F E : (a : F) → E) c) ⋯) :
            (↥F⟮γ⟯)[X])
          X)))
    (Polynomial.map (algebraMap F ↥F⟮γ⟯) g)
h : E[X] :=
  EuclideanDomain.gcd
    ((Polynomial.map ιFE f).comp
      (HSub.hSub (α := E[X]) ((C : (a : E) → E[X]) γ : E[X])
        (HMul.hMul (α := E[X]) (β := E[X]) ((C : (a : E) → E[X]) ((ιFE : (a : F) → E) c) : E[X]) X)))
    (Polynomial.map ιFE g)
map_g_ne_zero : Polynomial.map ιFE g ≠ 0
⊢ Membership.mem (γ := IntermediateField F E) F⟮γ⟯ β
have h_ne_zero : h ≠ 0
Tactic: have h_ne_zero : h ≠ 0 :=
    mt EuclideanDomain.gcd_eq_zero_iff.mp (not_and.mpr fun _ => map_g_ne_zero)
-- Lean 4 proof step from Mathlib.FieldTheory.PrimitiveElement (hypothesis)
Goal:
F : Type u_1
inst : Field F
inst_1 : Infinite F
E : Type u_2
inst_2 : Field E
α β : E
inst_3 : Algebra F E
inst_4 : Algebra.IsSeparable F E
hα : IsIntegral F α
hβ : IsIntegral F β
f : F[X] := minpoly F α
g : F[X] := minpoly F β
ιFE : F →+* E := algebraMap F E
ιEE' : E →+* (Polynomial.map ιFE g).SplittingField := algebraMap E (Polynomial.map ιFE g).SplittingField
c : F
hc :
  ∀ α' ∈ (Polynomial.map (ιEE'.comp ιFE) f).roots,
    ∀ β' ∈ (Polynomial.map (ιEE'.comp ιFE) g).roots,
      -HSub.hSub (β := (Polynomial.map ιFE g).SplittingField) α'
              ((ιEE' : (a : E) → (Polynomial.map ιFE g).SplittingField) α : (Polynomial.map ιFE g).SplittingField) /
          HSub.hSub (β := (Polynomial.map ιFE g).SplittingField) β'
            ((ιEE' : (a : E) → (Polynomial.map ιFE g).SplittingField) β : (Polynomial.map ιFE g).SplittingField) ≠
        (ιEE'.comp ιFE : (a : F) → (Polynomial.map ιFE g).SplittingField) c
γ : E := α + c • β
p : (↥F⟮γ⟯)[X] :=
  EuclideanDomain.gcd
    (comp (Polynomial.map (algebraMap F ↥F⟮γ⟯) f)
      (HSub.hSub (α := (↥F⟮γ⟯)[X]) ((C : (a : ↥F⟮γ⟯) → (↥F⟮γ⟯)[X]) (AdjoinSimple.gen F γ) : (↥F⟮γ⟯)[X])
        (HMul.hMul (α := (↥F⟮γ⟯)[X]) (β := (↥F⟮γ⟯)[X])
          ((C : (a : ↥F⟮γ⟯) → (↥F⟮γ⟯)[X])
              (Subtype.mk (p := fun (x : E) ↦ Membership.mem (γ := IntermediateField F E) F⟮γ⟯ x)
                ((algebraMap F E : (a : F) → E) c) ⋯) :
            (↥F⟮γ⟯)[X])
          X)))
    (Polynomial.map (algebraMap F ↥F⟮γ⟯) g)
h : E[X] :=
  EuclideanDomain.gcd
    ((Polynomial.map ιFE f).comp
      (HSub.hSub (α := E[X]) ((C : (a : E) → E[X]) γ : E[X])
        (HMul.hMul (α := E[X]) (β := E[X]) ((C : (a : E) → E[X]) ((ιFE : (a : F) → E) c) : E[X]) X)))
    (Polynomial.map ιFE g)
map_g_ne_zero : Polynomial.map ιFE g ≠ 0
h_ne_zero : h ≠ 0
p_linear :
  Polynomial.map (algebraMap (↥F⟮γ⟯) E) p =
    HMul.hMul (α := E[X]) ((C : (a : E) → E[X]) h.leadingCoeff : E[X])
      (HSub.hSub (α := E[X]) (β := E[X]) X ((C : (a : E) → E[X]) β : E[X]))
⊢ Membership.mem (γ := IntermediateField F E) F⟮γ⟯ β
have finale : β = (algebraMap (↥F⟮γ⟯) E : (a : ↥F⟮γ⟯) → E) (-p.coeff 0 / p.coeff 1)
Tactic: have finale : β = algebraMap F⟮γ⟯ E (-p.coeff 0 / p.coeff 1) := by
      simp [map_div₀, map_neg, ← coeff_map, ← coeff_map, p_linear,
        mul_sub, coeff_C, mul_div_cancel_left₀ β (mt leadingCoeff_eq_zero.mp h_ne_zero)]
-- Lean 4 proof step from Mathlib.FieldTheory.PrimitiveElement (goal)
Goal:
F : Type u_1
inst : Field F
inst_1 : Infinite F
E : Type u_2
inst_2 : Field E
α β : E
inst_3 : Algebra F E
inst_4 : Algebra.IsSeparable F E
hα : IsIntegral F α
hβ : IsIntegral F β
f : F[X] := minpoly F α
g : F[X] := minpoly F β
ιFE : F →+* E := algebraMap F E
ιEE' : E →+* (Polynomial.map ιFE g).SplittingField := algebraMap E (Polynomial.map ιFE g).SplittingField
c : F
hc :
  ∀ α' ∈ (Polynomial.map (ιEE'.comp ιFE) f).roots,
    ∀ β' ∈ (Polynomial.map (ιEE'.comp ιFE) g).roots,
      -HSub.hSub (β := (Polynomial.map ιFE g).SplittingField) α'
              ((ιEE' : (a : E) → (Polynomial.map ιFE g).SplittingField) α : (Polynomial.map ιFE g).SplittingField) /
          HSub.hSub (β := (Polynomial.map ιFE g).SplittingField) β'
            ((ιEE' : (a : E) → (Polynomial.map ιFE g).SplittingField) β : (Polynomial.map ιFE g).SplittingField) ≠
        (ιEE'.comp ιFE : (a : F) → (Polynomial.map ιFE g).SplittingField) c
γ : E := α + c • β
p : (↥F⟮γ⟯)[X] :=
  EuclideanDomain.gcd
    (comp (Polynomial.map (algebraMap F ↥F⟮γ⟯) f)
      (HSub.hSub (α := (↥F⟮γ⟯)[X]) ((C : (a : ↥F⟮γ⟯) → (↥F⟮γ⟯)[X]) (AdjoinSimple.gen F γ) : (↥F⟮γ⟯)[X])
        (HMul.hMul (α := (↥F⟮γ⟯)[X]) (β := (↥F⟮γ⟯)[X])
          ((C : (a : ↥F⟮γ⟯) → (↥F⟮γ⟯)[X])
              (Subtype.mk (p := fun (x : E) ↦ Membership.mem (γ := IntermediateField F E) F⟮γ⟯ x)
                ((algebraMap F E : (a : F) → E) c) ⋯) :
            (↥F⟮γ⟯)[X])
          X)))
    (Polynomial.map (algebraMap F ↥F⟮γ⟯) g)
h : E[X] :=
  EuclideanDomain.gcd
    ((Polynomial.map ιFE f).comp
      (HSub.hSub (α := E[X]) ((C : (a : E) → E[X]) γ : E[X])
        (HMul.hMul (α := E[X]) (β := E[X]) ((C : (a : E) → E[X]) ((ιFE : (a : F) → E) c) : E[X]) X)))
    (Polynomial.map ιFE g)
map_g_ne_zero : Polynomial.map ιFE g ≠ 0
h_ne_zero : h ≠ 0
p_linear :
  Polynomial.map (algebraMap (↥F⟮γ⟯) E) p =
    HMul.hMul (α := E[X]) ((C : (a : E) → E[X]) h.leadingCoeff : E[X])
      (HSub.hSub (α := E[X]) (β := E[X]) X ((C : (a : E) → E[X]) β : E[X]))
finale : β = (algebraMap (↥F⟮γ⟯) E : (a : ↥F⟮γ⟯) → E) (-p.coeff 0 / p.coeff 1)
⊢ Membership.mem (γ := IntermediateField F E) F⟮γ⟯ β
have rw : Membership.mem (α := E) (γ := IntermediateField F E) F⟮γ⟯
  ((algebraMap (↥F⟮γ⟯) E : (a : ↥F⟮γ⟯) → E) (-p.coeff 0 / p.coeff 1) : E)
Tactic: rw [finale]
-- Lean 4 proof step from Mathlib.FieldTheory.PrimitiveElement (goal)
Goal:
F : Type u_1
inst : Field F
inst_1 : Infinite F
E : Type u_2
inst_2 : Field E
α β : E
inst_3 : Algebra F E
inst_4 : Algebra.IsSeparable F E
hα : IsIntegral F α
hβ : IsIntegral F β
f : F[X] := minpoly F α
g : F[X] := minpoly F β
ιFE : F →+* E := algebraMap F E
ιEE' : E →+* (Polynomial.map ιFE g).SplittingField := algebraMap E (Polynomial.map ιFE g).SplittingField
c : F
hc :
  ∀ α' ∈ (Polynomial.map (ιEE'.comp ιFE) f).roots,
    ∀ β' ∈ (Polynomial.map (ιEE'.comp ιFE) g).roots,
      -HSub.hSub (β := (Polynomial.map ιFE g).SplittingField) α'
              ((ιEE' : (a : E) → (Polynomial.map ιFE g).SplittingField) α : (Polynomial.map ιFE g).SplittingField) /
          HSub.hSub (β := (Polynomial.map ιFE g).SplittingField) β'
            ((ιEE' : (a : E) → (Polynomial.map ιFE g).SplittingField) β : (Polynomial.map ιFE g).SplittingField) ≠
        (ιEE'.comp ιFE : (a : F) → (Polynomial.map ιFE g).SplittingField) c
γ : E := α + c • β
p : (↥F⟮γ⟯)[X] :=
  EuclideanDomain.gcd
    (comp (Polynomial.map (algebraMap F ↥F⟮γ⟯) f)
      (HSub.hSub (α := (↥F⟮γ⟯)[X]) ((C : (a : ↥F⟮γ⟯) → (↥F⟮γ⟯)[X]) (AdjoinSimple.gen F γ) : (↥F⟮γ⟯)[X])
        (HMul.hMul (α := (↥F⟮γ⟯)[X]) (β := (↥F⟮γ⟯)[X])
          ((C : (a : ↥F⟮γ⟯) → (↥F⟮γ⟯)[X])
              (Subtype.mk (p := fun (x : E) ↦ Membership.mem (γ := IntermediateField F E) F⟮γ⟯ x)
                ((algebraMap F E : (a : F) → E) c) ⋯) :
            (↥F⟮γ⟯)[X])
          X)))
    (Polynomial.map (algebraMap F ↥F⟮γ⟯) g)
h : E[X] :=
  EuclideanDomain.gcd
    ((Polynomial.map ιFE f).comp
      (HSub.hSub (α := E[X]) ((C : (a : E) → E[X]) γ : E[X])
        (HMul.hMul (α := E[X]) (β := E[X]) ((C : (a : E) → E[X]) ((ιFE : (a : F) → E) c) : E[X]) X)))
    (Polynomial.map ιFE g)
map_g_ne_zero : Polynomial.map ιFE g ≠ 0
h_ne_zero : h ≠ 0
⊢ Membership.mem (γ := IntermediateField F E) F⟮γ⟯ β
have suffices : Polynomial.map (algebraMap (↥F⟮γ⟯) E) p =
  HMul.hMul (α := E[X]) ((C : (a : E) → E[X]) h.leadingCoeff : E[X])
    (HSub.hSub (α := E[X]) (β := E[X]) X ((C : (a : E) → E[X]) β : E[X]))
Tactic: suffices p_linear : p.map (algebraMap F⟮γ⟯ E) = C h.leadingCoeff * (X - C β) by
    have finale : β = algebraMap F⟮γ⟯ E (-p.coeff 0 / p.coeff 1) := by
      simp [map_div₀, map_neg, ← coeff_map, ← coeff_map, p_linear,
        mul_sub, coeff_C, mul_div_cancel_left₀ β (mt leadingCoeff_eq_zero.mp h_ne_zero)]
    rw [finale]
    exact Subtype.mem (-p.coeff 0 / p.coeff 1)
-- Lean 4 proof step from Mathlib.FieldTheory.PrimitiveElement (hypothesis)
Goal:
F : Type u_1
inst : Field F
inst_1 : Infinite F
E : Type u_2
inst_2 : Field E
α β : E
inst_3 : Algebra F E
inst_4 : Algebra.IsSeparable F E
hα : IsIntegral F α
hβ : IsIntegral F β
f : F[X] := minpoly F α
g : F[X] := minpoly F β
ιFE : F →+* E := algebraMap F E
ιEE' : E →+* (Polynomial.map ιFE g).SplittingField := algebraMap E (Polynomial.map ιFE g).SplittingField
c : F
hc :
  ∀ α' ∈ (Polynomial.map (ιEE'.comp ιFE) f).roots,
    ∀ β' ∈ (Polynomial.map (ιEE'.comp ιFE) g).roots,
      -HSub.hSub (β := (Polynomial.map ιFE g).SplittingField) α'
              ((ιEE' : (a : E) → (Polynomial.map ιFE g).SplittingField) α : (Polynomial.map ιFE g).SplittingField) /
          HSub.hSub (β := (Polynomial.map ιFE g).SplittingField) β'
            ((ιEE' : (a : E) → (Polynomial.map ιFE g).SplittingField) β : (Polynomial.map ιFE g).SplittingField) ≠
        (ιEE'.comp ιFE : (a : F) → (Polynomial.map ιFE g).SplittingField) c
γ : E := α + c • β
p : (↥F⟮γ⟯)[X] :=
  EuclideanDomain.gcd
    (comp (Polynomial.map (algebraMap F ↥F⟮γ⟯) f)
      (HSub.hSub (α := (↥F⟮γ⟯)[X]) ((C : (a : ↥F⟮γ⟯) → (↥F⟮γ⟯)[X]) (AdjoinSimple.gen F γ) : (↥F⟮γ⟯)[X])
        (HMul.hMul (α := (↥F⟮γ⟯)[X]) (β := (↥F⟮γ⟯)[X])
          ((C : (a : ↥F⟮γ⟯) → (↥F⟮γ⟯)[X])
              (Subtype.mk (p := fun (x : E) ↦ Membership.mem (γ := IntermediateField F E) F⟮γ⟯ x)
                ((algebraMap F E : (a : F) → E) c) ⋯) :
            (↥F⟮γ⟯)[X])
          X)))
    (Polynomial.map (algebraMap F ↥F⟮γ⟯) g)
h : E[X] :=
  EuclideanDomain.gcd
    ((Polynomial.map ιFE f).comp
      (HSub.hSub (α := E[X]) ((C : (a : E) → E[X]) γ : E[X])
        (HMul.hMul (α := E[X]) (β := E[X]) ((C : (a : E) → E[X]) ((ιFE : (a : F) → E) c) : E[X]) X)))
    (Polynomial.map ιFE g)
map_g_ne_zero : Polynomial.map ιFE g ≠ 0
h_ne_zero : h ≠ 0
⊢ Polynomial.map (algebraMap (↥F⟮γ⟯) E) p =
    HMul.hMul (α := E[X]) ((C : (a : E) → E[X]) h.leadingCoeff : E[X])
      (HSub.hSub (α := E[X]) (β := E[X]) X ((C : (a : E) → E[X]) β : E[X]))
have h_sep : h.Separable
Tactic: have h_sep : h.Separable := separable_gcd_right _ (.map (Algebra.IsSeparable.isSeparable F β))
-- Lean 4 proof step from Mathlib.FieldTheory.PrimitiveElement (goal)
Goal:
F : Type u_1
inst : Field F
inst_1 : Infinite F
E : Type u_2
inst_2 : Field E
α β : E
inst_3 : Algebra F E
inst_4 : Algebra.IsSeparable F E
hα : IsIntegral F α
hβ : IsIntegral F β
f : F[X] := minpoly F α
g : F[X] := minpoly F β
ιFE : F →+* E := algebraMap F E
ιEE' : E →+* (Polynomial.map ιFE g).SplittingField := algebraMap E (Polynomial.map ιFE g).SplittingField
c : F
hc :
  ∀ α' ∈ (Polynomial.map (ιEE'.comp ιFE) f).roots,
    ∀ β' ∈ (Polynomial.map (ιEE'.comp ιFE) g).roots,
      -HSub.hSub (β := (Polynomial.map ιFE g).SplittingField) α'
              ((ιEE' : (a : E) → (Polynomial.map ιFE g).SplittingField) α : (Polynomial.map ιFE g).SplittingField) /
          HSub.hSub (β := (Polynomial.map ιFE g).SplittingField) β'
            ((ιEE' : (a : E) → (Polynomial.map ιFE g).SplittingField) β : (Polynomial.map ιFE g).SplittingField) ≠
        (ιEE'.comp ιFE : (a : F) → (Polynomial.map ιFE g).SplittingField) c
γ : E := α + c • β
p : (↥F⟮γ⟯)[X] :=
  EuclideanDomain.gcd
    (comp (Polynomial.map (algebraMap F ↥F⟮γ⟯) f)
      (HSub.hSub (α := (↥F⟮γ⟯)[X]) ((C : (a : ↥F⟮γ⟯) → (↥F⟮γ⟯)[X]) (AdjoinSimple.gen F γ) : (↥F⟮γ⟯)[X])
        (HMul.hMul (α := (↥F⟮γ⟯)[X]) (β := (↥F⟮γ⟯)[X])
          ((C : (a : ↥F⟮γ⟯) → (↥F⟮γ⟯)[X])
              (Subtype.mk (p := fun (x : E) ↦ Membership.mem (γ := IntermediateField F E) F⟮γ⟯ x)
                ((algebraMap F E : (a : F) → E) c) ⋯) :
            (↥F⟮γ⟯)[X])
          X)))
    (Polynomial.map (algebraMap F ↥F⟮γ⟯) g)
h : E[X] :=
  EuclideanDomain.gcd
    ((Polynomial.map ιFE f).comp
      (HSub.hSub (α := E[X]) ((C : (a : E) → E[X]) γ : E[X])
        (HMul.hMul (α := E[X]) (β := E[X]) ((C : (a : E) → E[X]) ((ιFE : (a : F) → E) c) : E[X]) X)))
    (Polynomial.map ιFE g)
map_g_ne_zero : Polynomial.map ιFE g ≠ 0
h_ne_zero : h ≠ 0
h_sep : h.Separable
⊢ eval β h = 0
have hf : eval β
    ((Polynomial.map ιFE f).comp
      (HSub.hSub (α := E[X]) ((C : (a : E) → E[X]) γ : E[X])
        (HMul.hMul (α := E[X]) (β := E[X]) ((C : (a : E) → E[X]) ((ιFE : (a : F) → E) c) : E[X]) X))) =
  0
Tactic: apply eval_gcd_eq_zero
-- Lean 4 proof step from Mathlib.FieldTheory.PrimitiveElement (goal)
Goal:
F : Type u_1
inst : Field F
inst_1 : Infinite F
E : Type u_2
inst_2 : Field E
α β : E
inst_3 : Algebra F E
inst_4 : Algebra.IsSeparable F E
hα : IsIntegral F α
hβ : IsIntegral F β
f : F[X] := minpoly F α
g : F[X] := minpoly F β
ιFE : F →+* E := algebraMap F E
ιEE' : E →+* (Polynomial.map ιFE g).SplittingField := algebraMap E (Polynomial.map ιFE g).SplittingField
c : F
hc :
  ∀ α' ∈ (Polynomial.map (ιEE'.comp ιFE) f).roots,
    ∀ β' ∈ (Polynomial.map (ιEE'.comp ιFE) g).roots,
      -HSub.hSub (β := (Polynomial.map ιFE g).SplittingField) α'
              ((ιEE' : (a : E) → (Polynomial.map ιFE g).SplittingField) α : (Polynomial.map ιFE g).SplittingField) /
          HSub.hSub (β := (Polynomial.map ιFE g).SplittingField) β'
            ((ιEE' : (a : E) → (Polynomial.map ιFE g).SplittingField) β : (Polynomial.map ιFE g).SplittingField) ≠
        (ιEE'.comp ιFE : (a : F) → (Polynomial.map ιFE g).SplittingField) c
γ : E := α + c • β
p : (↥F⟮γ⟯)[X] :=
  EuclideanDomain.gcd
    (comp (Polynomial.map (algebraMap F ↥F⟮γ⟯) f)
      (HSub.hSub (α := (↥F⟮γ⟯)[X]) ((C : (a : ↥F⟮γ⟯) → (↥F⟮γ⟯)[X]) (AdjoinSimple.gen F γ) : (↥F⟮γ⟯)[X])
        (HMul.hMul (α := (↥F⟮γ⟯)[X]) (β := (↥F⟮γ⟯)[X])
          ((C : (a : ↥F⟮γ⟯) → (↥F⟮γ⟯)[X])
              (Subtype.mk (p := fun (x : E) ↦ Membership.mem (γ := IntermediateField F E) F⟮γ⟯ x)
                ((algebraMap F E : (a : F) → E) c) ⋯) :
            (↥F⟮γ⟯)[X])
          X)))
    (Polynomial.map (algebraMap F ↥F⟮γ⟯) g)
h : E[X] :=
  EuclideanDomain.gcd
    ((Polynomial.map ιFE f).comp
      (HSub.hSub (α := E[X]) ((C : (a : E) → E[X]) γ : E[X])
        (HMul.hMul (α := E[X]) (β := E[X]) ((C : (a : E) → E[X]) ((ιFE : (a : F) → E) c) : E[X]) X)))
    (Polynomial.map ιFE g)
map_g_ne_zero : Polynomial.map ιFE g ≠ 0
h_ne_zero : h ≠ 0
h_sep : h.Separable
hf :
  eval β
      ((Polynomial.map ιFE f).comp
        (HSub.hSub (α := E[X]) ((C : (a : E) → E[X]) γ : E[X])
          (HMul.hMul (α := E[X]) (β := E[X]) ((C : (a : E) → E[X]) ((ιFE : (a : F) → E) c) : E[X]) X))) =
    0
⊢ eval β h = 0
have hg : eval β (Polynomial.map ιFE g) = 0
Tactic: apply eval_gcd_eq_zero
-- Lean 4 proof step from Mathlib.FieldTheory.PrimitiveElement (goal)
Goal:
F : Type u_1
inst : Field F
inst_1 : Infinite F
E : Type u_2
inst_2 : Field E
α β : E
inst_3 : Algebra F E
inst_4 : Algebra.IsSeparable F E
hα : IsIntegral F α
hβ : IsIntegral F β
f : F[X] := minpoly F α
g : F[X] := minpoly F β
ιFE : F →+* E := algebraMap F E
ιEE' : E →+* (Polynomial.map ιFE g).SplittingField := algebraMap E (Polynomial.map ιFE g).SplittingField
c : F
hc :
  ∀ α' ∈ (Polynomial.map (ιEE'.comp ιFE) f).roots,
    ∀ β' ∈ (Polynomial.map (ιEE'.comp ιFE) g).roots,
      -HSub.hSub (β := (Polynomial.map ιFE g).SplittingField) α'
              ((ιEE' : (a : E) → (Polynomial.map ιFE g).SplittingField) α : (Polynomial.map ιFE g).SplittingField) /
          HSub.hSub (β := (Polynomial.map ιFE g).SplittingField) β'
            ((ιEE' : (a : E) → (Polynomial.map ιFE g).SplittingField) β : (Polynomial.map ιFE g).SplittingField) ≠
        (ιEE'.comp ιFE : (a : F) → (Polynomial.map ιFE g).SplittingField) c
γ : E := α + c • β
p : (↥F⟮γ⟯)[X] :=
  EuclideanDomain.gcd
    (comp (Polynomial.map (algebraMap F ↥F⟮γ⟯) f)
      (HSub.hSub (α := (↥F⟮γ⟯)[X]) ((C : (a : ↥F⟮γ⟯) → (↥F⟮γ⟯)[X]) (AdjoinSimple.gen F γ) : (↥F⟮γ⟯)[X])
        (HMul.hMul (α := (↥F⟮γ⟯)[X]) (β := (↥F⟮γ⟯)[X])
          ((C : (a : ↥F⟮γ⟯) → (↥F⟮γ⟯)[X])
              (Subtype.mk (p := fun (x : E) ↦ Membership.mem (γ := IntermediateField F E) F⟮γ⟯ x)
                ((algebraMap F E : (a : F) → E) c) ⋯) :
            (↥F⟮γ⟯)[X])
          X)))
    (Polynomial.map (algebraMap F ↥F⟮γ⟯) g)
h : E[X] :=
  EuclideanDomain.gcd
    ((Polynomial.map ιFE f).comp
      (HSub.hSub (α := E[X]) ((C : (a : E) → E[X]) γ : E[X])
        (HMul.hMul (α := E[X]) (β := E[X]) ((C : (a : E) → E[X]) ((ιFE : (a : F) → E) c) : E[X]) X)))
    (Polynomial.map ιFE g)
map_g_ne_zero : Polynomial.map ιFE g ≠ 0
h_ne_zero : h ≠ 0
h_sep : h.Separable
⊢ eval β
      ((Polynomial.map ιFE f).comp
        (HSub.hSub (α := E[X]) ((C : (a : E) → E[X]) γ : E[X])
          (HMul.hMul (α := E[X]) (β := E[X]) ((C : (a : E) → E[X]) ((ιFE : (a : F) → E) c) : E[X]) X))) =
    0
have hf : eval
    (eval β
      (HSub.hSub (α := E[X]) ((C : (a : E) → E[X]) γ : E[X])
        (HMul.hMul (α := E[X]) (β := E[X]) ((C : (a : E) → E[X]) ((ιFE : (a : F) → E) c) : E[X]) X)))
    (Polynomial.map ιFE f) =
  0
Tactic: rw [eval_comp, eval_sub, eval_mul, eval_C, eval_C, eval_X, eval_map_algebraMap, ←
        Algebra.smul_def, add_sub_cancel_right, minpoly.aeval]