Theorem: Field.primitive_element_inf_aux_exists_c
File: Mathlib/FieldTheory/PrimitiveElement.lean

tactic: let sf := (f.map ϕ).roots
state_before: F : Type u_1
inst✝² : Field F
inst✝¹ : Infinite F
E : Type u_2
inst✝ : Field E
ϕ : F →+* E
α β : E
f g : F[X]
⊢ ∃ c, ∀ α' ∈ (Polynomial.map ϕ f).roots, ∀ β' ∈ (Polynomial.map ϕ g).roots, -(α' - α) / (β' - β) ≠ ϕ c
state_after: F : Type u_1
inst✝² : Field F
inst✝¹ : Infinite F
E : Type u_2
inst✝ : Field E
ϕ : F →+* E
α β : E
f g : F[X]
sf : Multiset E := (Polynomial.map ϕ f).roots
⊢ ∃ c, ∀ α' ∈ (Polynomial.map ϕ f).roots, ∀ β' ∈ (Polynomial.map ϕ g).roots, -(α' - α) / (β' - β) ≠ ϕ c

tactic: let sg := (g.map ϕ).roots
state_before: F : Type u_1
inst✝² : Field F
inst✝¹ : Infinite F
E : Type u_2
inst✝ : Field E
ϕ : F →+* E
α β : E
f g : F[X]
sf : Multiset E := (Polynomial.map ϕ f).roots
⊢ ∃ c, ∀ α' ∈ (Polynomial.map ϕ f).roots, ∀ β' ∈ (Polynomial.map ϕ g).roots, -(α' - α) / (β' - β) ≠ ϕ c
state_after: F : Type u_1
inst✝² : Field F
inst✝¹ : Infinite F
E : Type u_2
inst✝ : Field E
ϕ : F →+* E
α β : E
f g : F[X]
sf : Multiset E := (Polynomial.map ϕ f).roots
sg : Multiset E := (Polynomial.map ϕ g).roots
⊢ ∃ c, ∀ α' ∈ (Polynomial.map ϕ f).roots, ∀ β' ∈ (Polynomial.map ϕ g).roots, -(α' - α) / (β' - β) ≠ ϕ c

tactic: let s := (sf.bind fun α' => sg.map fun β' => -(α' - α) / (β' - β)).toFinset
state_before: F : Type u_1
inst✝² : Field F
inst✝¹ : Infinite F
E : Type u_2
inst✝ : Field E
ϕ : F →+* E
α β : E
f g : F[X]
sf : Multiset E := (Polynomial.map ϕ f).roots
sg : Multiset E := (Polynomial.map ϕ g).roots
⊢ ∃ c, ∀ α' ∈ (Polynomial.map ϕ f).roots, ∀ β' ∈ (Polynomial.map ϕ g).roots, -(α' - α) / (β' - β) ≠ ϕ c
state_after: F : Type u_1
inst✝² : Field F
inst✝¹ : Infinite F
E : Type u_2
inst✝ : Field E
ϕ : F →+* E
α β : E
f g : F[X]
sf : Multiset E := (Polynomial.map ϕ f).roots
sg : Multiset E := (Polynomial.map ϕ g).roots
s : Finset E := (sf.bind fun α' => Multiset.map (fun β' => -(α' - α) / (β' - β)) sg).toFinset
⊢ ∃ c, ∀ α' ∈ (Polynomial.map ϕ f).roots, ∀ β' ∈ (Polynomial.map ϕ g).roots, -(α' - α) / (β' - β) ≠ ϕ c

tactic: let s' := s.preimage ϕ fun x _ y _ h => ϕ.injective h
state_before: F : Type u_1
inst✝² : Field F
inst✝¹ : Infinite F
E : Type u_2
inst✝ : Field E
ϕ : F →+* E
α β : E
f g : F[X]
sf : Multiset E := (Polynomial.map ϕ f).roots
sg : Multiset E := (Polynomial.map ϕ g).roots
s : Finset E := (sf.bind fun α' => Multiset.map (fun β' => -(α' - α) / (β' - β)) sg).toFinset
⊢ ∃ c, ∀ α' ∈ (Polynomial.map ϕ f).roots, ∀ β' ∈ (Polynomial.map ϕ g).roots, -(α' - α) / (β' - β) ≠ ϕ c
state_after: F : Type u_1
inst✝² : Field F
inst✝¹ : Infinite F
E : Type u_2
inst✝ : Field E
ϕ : F →+* E
α β : E
f g : F[X]
sf : Multiset E := (Polynomial.map ϕ f).roots
sg : Multiset E := (Polynomial.map ϕ g).roots
s : Finset E := (sf.bind fun α' => Multiset.map (fun β' => -(α' - α) / (β' - β)) sg).toFinset
s' : Finset F := s.preimage ⇑ϕ ⋯
⊢ ∃ c, ∀ α' ∈ (Polynomial.map ϕ f).roots, ∀ β' ∈ (Polynomial.map ϕ g).roots, -(α' - α) / (β' - β) ≠ ϕ c

tactic: obtain ⟨c, hc⟩ := Infinite.exists_not_mem_finset s'
state_before: F : Type u_1
inst✝² : Field F
inst✝¹ : Infinite F
E : Type u_2
inst✝ : Field E
ϕ : F →+* E
α β : E
f g : F[X]
sf : Multiset E := (Polynomial.map ϕ f).roots
sg : Multiset E := (Polynomial.map ϕ g).roots
s : Finset E := (sf.bind fun α' => Multiset.map (fun β' => -(α' - α) / (β' - β)) sg).toFinset
s' : Finset F := s.preimage ⇑ϕ ⋯
⊢ ∃ c, ∀ α' ∈ (Polynomial.map ϕ f).roots, ∀ β' ∈ (Polynomial.map ϕ g).roots, -(α' - α) / (β' - β) ≠ ϕ c
state_after: case intro
F : Type u_1
inst✝² : Field F
inst✝¹ : Infinite F
E : Type u_2
inst✝ : Field E
ϕ : F →+* E
α β : E
f g : F[X]
sf : Multiset E := (Polynomial.map ϕ f).roots
sg : Multiset E := (Polynomial.map ϕ g).roots
s : Finset E := (sf.bind fun α' => Multiset.map (fun β' => -(α' - α) / (β' - β)) sg).toFinset
s' : Finset F := s.preimage ⇑ϕ ⋯
c : F
hc : c ∉ s'
⊢ ∃ c, ∀ α' ∈ (Polynomial.map ϕ f).roots, ∀ β' ∈ (Polynomial.map ϕ g).roots, -(α' - α) / (β' - β) ≠ ϕ c

tactic: simp_rw [s', s, Finset.mem_preimage, Multiset.mem_toFinset, Multiset.mem_bind, Multiset.mem_map]
  at hc
state_before: case intro
F : Type u_1
inst✝² : Field F
inst✝¹ : Infinite F
E : Type u_2
inst✝ : Field E
ϕ : F →+* E
α β : E
f g : F[X]
sf : Multiset E := (Polynomial.map ϕ f).roots
sg : Multiset E := (Polynomial.map ϕ g).roots
s : Finset E := (sf.bind fun α' => Multiset.map (fun β' => -(α' - α) / (β' - β)) sg).toFinset
s' : Finset F := s.preimage ⇑ϕ ⋯
c : F
hc : c ∉ s'
⊢ ∃ c, ∀ α' ∈ (Polynomial.map ϕ f).roots, ∀ β' ∈ (Polynomial.map ϕ g).roots, -(α' - α) / (β' - β) ≠ ϕ c
state_after: case intro
F : Type u_1
inst✝² : Field F
inst✝¹ : Infinite F
E : Type u_2
inst✝ : Field E
ϕ : F →+* E
α β : E
f g : F[X]
sf : Multiset E := (Polynomial.map ϕ f).roots
sg : Multiset E := (Polynomial.map ϕ g).roots
s : Finset E := (sf.bind fun α' => Multiset.map (fun β' => -(α' - α) / (β' - β)) sg).toFinset
s' : Finset F := s.preimage ⇑ϕ ⋯
c : F
hc : ¬∃ a ∈ sf, ∃ a_1 ∈ sg, -(a - α) / (a_1 - β) = ϕ c
⊢ ∃ c, ∀ α' ∈ (Polynomial.map ϕ f).roots, ∀ β' ∈ (Polynomial.map ϕ g).roots, -(α' - α) / (β' - β) ≠ ϕ c

tactic: push_neg at hc
state_before: case intro
F : Type u_1
inst✝² : Field F
inst✝¹ : Infinite F
E : Type u_2
inst✝ : Field E
ϕ : F →+* E
α β : E
f g : F[X]
sf : Multiset E := (Polynomial.map ϕ f).roots
sg : Multiset E := (Polynomial.map ϕ g).roots
s : Finset E := (sf.bind fun α' => Multiset.map (fun β' => -(α' - α) / (β' - β)) sg).toFinset
s' : Finset F := s.preimage ⇑ϕ ⋯
c : F
hc : ¬∃ a ∈ sf, ∃ a_1 ∈ sg, -(a - α) / (a_1 - β) = ϕ c
⊢ ∃ c, ∀ α' ∈ (Polynomial.map ϕ f).roots, ∀ β' ∈ (Polynomial.map ϕ g).roots, -(α' - α) / (β' - β) ≠ ϕ c
state_after: case intro
F : Type u_1
inst✝² : Field F
inst✝¹ : Infinite F
E : Type u_2
inst✝ : Field E
ϕ : F →+* E
α β : E
f g : F[X]
sf : Multiset E := (Polynomial.map ϕ f).roots
sg : Multiset E := (Polynomial.map ϕ g).roots
s : Finset E := (sf.bind fun α' => Multiset.map (fun β' => -(α' - α) / (β' - β)) sg).toFinset
s' : Finset F := s.preimage ⇑ϕ ⋯
c : F
hc : ∀ a ∈ sf, ∀ a_1 ∈ sg, -(a - α) / (a_1 - β) ≠ ϕ c
⊢ ∃ c, ∀ α' ∈ (Polynomial.map ϕ f).roots, ∀ β' ∈ (Polynomial.map ϕ g).roots, -(α' - α) / (β' - β) ≠ ϕ c

tactic: exact ⟨c, hc⟩
state_before: case intro
F : Type u_1
inst✝² : Field F
inst✝¹ : Infinite F
E : Type u_2
inst✝ : Field E
ϕ : F →+* E
α β : E
f g : F[X]
sf : Multiset E := (Polynomial.map ϕ f).roots
sg : Multiset E := (Polynomial.map ϕ g).roots
s : Finset E := (sf.bind fun α' => Multiset.map (fun β' => -(α' - α) / (β' - β)) sg).toFinset
s' : Finset F := s.preimage ⇑ϕ ⋯
c : F
hc : ∀ a ∈ sf, ∀ a_1 ∈ sg, -(a - α) / (a_1 - β) ≠ ϕ c
⊢ ∃ c, ∀ α' ∈ (Polynomial.map ϕ f).roots, ∀ β' ∈ (Polynomial.map ϕ g).roots, -(α' - α) / (β' - β) ≠ ϕ c
state_after: no goals