Theorem: Complex.liouville_theorem_aux
File: Mathlib/Analysis/Complex/Liouville.lean

Proof steps:
state_before: E : Type u
inst✝³ : NormedAddCommGroup E
inst✝² : NormedSpace ℂ E
F : Type v
inst✝¹ : NormedAddCommGroup F
inst✝ : NormedSpace ℂ F
f : ℂ → F
hf : Differentiable ℂ f
hb : Bornology.IsBounded (range f)
z w : ℂ
⊢ f z = f w
state_after: E : Type u
inst✝³ : NormedAddCommGroup E
inst✝² : NormedSpace ℂ E
F : Type v
inst✝¹ : NormedAddCommGroup F
inst✝ : NormedSpace ℂ F
f : ℂ → F
hf : Differentiable ℂ f
hb : Bornology.IsBounded (range f)
z w : ℂ
⊢ ∀ (c : ℂ), deriv f c = 0
tactic: suffices ∀ c, deriv f c = 0 from is_const_of_deriv_eq_zero hf this z w
state_before: E : Type u
inst✝³ : NormedAddCommGroup E
inst✝² : NormedSpace ℂ E
F : Type v
inst✝¹ : NormedAddCommGroup F
inst✝ : NormedSpace ℂ F
f : ℂ → F
hf : Differentiable ℂ f
hb : Bornology.IsBounded (range f)
z w : ℂ
⊢ ∀ (c : ℂ), deriv f c = 0
state_after: E : Type u
inst✝³ : NormedAddCommGroup E
inst✝² : NormedSpace ℂ E
F : Type v
inst✝¹ : NormedAddCommGroup F
inst✝ : NormedSpace ℂ F
f : ℂ → F
hf : Differentiable ℂ f
hb : Bornology.IsBounded (range f)
⊢ ∀ (c : ℂ), deriv f c = 0
tactic: clear z w
state_before: E : Type u
inst✝³ : NormedAddCommGroup E
inst✝² : NormedSpace ℂ E
F : Type v
inst✝¹ : NormedAddCommGroup F
inst✝ : NormedSpace ℂ F
f : ℂ → F
hf : Differentiable ℂ f
hb : Bornology.IsBounded (range f)
⊢ ∀ (c : ℂ), deriv f c = 0
state_after: E : Type u
inst✝³ : NormedAddCommGroup E
inst✝² : NormedSpace ℂ E
F : Type v
inst✝¹ : NormedAddCommGroup F
inst✝ : NormedSpace ℂ F
f : ℂ → F
hf : Differentiable ℂ f
hb : Bornology.IsBounded (range f)
c : ℂ
⊢ deriv f c = 0
tactic: intro c
state_before: E : Type u
inst✝³ : NormedAddCommGroup E
inst✝² : NormedSpace ℂ E
F : Type v
inst✝¹ : NormedAddCommGroup F
inst✝ : NormedSpace ℂ F
f : ℂ → F
hf : Differentiable ℂ f
hb : Bornology.IsBounded (range f)
c : ℂ
⊢ deriv f c = 0
state_after: case intro.intro
E : Type u
inst✝³ : NormedAddCommGroup E
inst✝² : NormedSpace ℂ E
F : Type v
inst✝¹ : NormedAddCommGroup F
inst✝ : NormedSpace ℂ F
f : ℂ → F
hf : Differentiable ℂ f
hb : Bornology.IsBounded (range f)
c : ℂ
C : ℝ
C₀ : C > 0
hC : ∀ (z : ℂ), ‖f z‖ ≤ C
⊢ deriv f c = 0
tactic: obtain ⟨C, C₀, hC⟩ : ∃ C > (0 : ℝ), ∀ z, ‖f z‖ ≤ C := by
    rcases isBounded_iff_forall_norm_le.1 hb with ⟨C, hC⟩
    exact
      ⟨max C 1, lt_max_iff.2 (Or.inr zero_lt_one), fun z =>
        (hC (f z) (mem_range_self _)).trans (le_max_left _ _)⟩
state_before: case intro.intro
E : Type u
inst✝³ : NormedAddCommGroup E
inst✝² : NormedSpace ℂ E
F : Type v
inst✝¹ : NormedAddCommGroup F
inst✝ : NormedSpace ℂ F
f : ℂ → F
hf : Differentiable ℂ f
hb : Bornology.IsBounded (range f)
c : ℂ
C : ℝ
C₀ : C > 0
hC : ∀ (z : ℂ), ‖f z‖ ≤ C
⊢ deriv f c = 0
state_after: case intro.intro
E : Type u
inst✝³ : NormedAddCommGroup E
inst✝² : NormedSpace ℂ E
F : Type v
inst✝¹ : NormedAddCommGroup F
inst✝ : NormedSpace ℂ F
f : ℂ → F
hf : Differentiable ℂ f
hb : Bornology.IsBounded (range f)
c : ℂ
C : ℝ
C₀ : C > 0
hC : ∀ (z : ℂ), ‖f z‖ ≤ C
ε : ℝ
ε₀ : 0 < ε
⊢ ‖deriv f c‖ ≤ ε
tactic: refine norm_le_zero_iff.1 (le_of_forall_le_of_dense fun ε ε₀ => ?_)
state_before: case intro.intro
E : Type u
inst✝³ : NormedAddCommGroup E
inst✝² : NormedSpace ℂ E
F : Type v
inst✝¹ : NormedAddCommGroup F
inst✝ : NormedSpace ℂ F
f : ℂ → F
hf : Differentiable ℂ f
hb : Bornology.IsBounded (range f)
c : ℂ
C : ℝ
C₀ : C > 0
hC : ∀ (z : ℂ), ‖f z‖ ≤ C
ε : ℝ
ε₀ : 0 < ε
⊢ ‖deriv f c‖ ≤ ε
state_after: no goals
tactic: calc
    ‖deriv f c‖ ≤ C / (C / ε) :=
      norm_deriv_le_of_forall_mem_sphere_norm_le (div_pos C₀ ε₀) hf.diffContOnCl fun z _ => hC z
    _ = ε := div_div_cancel' C₀.lt.ne'