Theorem: has_unit_speed_naturalParameterization
File: Mathlib/Analysis/ConstantSpeed.lean

Proof steps:
state_before: α : Type u_1
inst✝¹ : LinearOrder α
E : Type u_2
inst✝ : PseudoEMetricSpace E
f✝ : ℝ → E
s✝ : Set ℝ
l : ℝ≥0
f : α → E
s : Set α
hf : LocallyBoundedVariationOn f s
a : α
as : a ∈ s
⊢ HasUnitSpeedOn (naturalParameterization f s a) (variationOnFromTo f s a '' s)
state_after: α : Type u_1
inst✝¹ : LinearOrder α
E : Type u_2
inst✝ : PseudoEMetricSpace E
f✝ : ℝ → E
s✝ : Set ℝ
l : ℝ≥0
f : α → E
s : Set α
hf : LocallyBoundedVariationOn f s
a : α
as : a ∈ s
⊢ HasConstantSpeedOnWith (naturalParameterization f s a) (variationOnFromTo f s a '' s) 1
tactic: dsimp only [HasUnitSpeedOn]
state_before: α : Type u_1
inst✝¹ : LinearOrder α
E : Type u_2
inst✝ : PseudoEMetricSpace E
f✝ : ℝ → E
s✝ : Set ℝ
l : ℝ≥0
f : α → E
s : Set α
hf : LocallyBoundedVariationOn f s
a : α
as : a ∈ s
⊢ HasConstantSpeedOnWith (naturalParameterization f s a) (variationOnFromTo f s a '' s) 1
state_after: α : Type u_1
inst✝¹ : LinearOrder α
E : Type u_2
inst✝ : PseudoEMetricSpace E
f✝ : ℝ → E
s✝ : Set ℝ
l : ℝ≥0
f : α → E
s : Set α
hf : LocallyBoundedVariationOn f s
a : α
as : a ∈ s
⊢ ∀ ⦃x : ℝ⦄,
    x ∈ variationOnFromTo f s a '' s →
      ∀ ⦃y : ℝ⦄,
        y ∈ variationOnFromTo f s a '' s →
          x ≤ y →
            eVariationOn (naturalParameterization f s a) (variationOnFromTo f s a '' s ∩ Icc x y) =
              ENNReal.ofReal (↑1 * (y - x))
tactic: rw [hasConstantSpeedOnWith_iff_ordered]
state_before: α : Type u_1
inst✝¹ : LinearOrder α
E : Type u_2
inst✝ : PseudoEMetricSpace E
f✝ : ℝ → E
s✝ : Set ℝ
l : ℝ≥0
f : α → E
s : Set α
hf : LocallyBoundedVariationOn f s
a : α
as : a ∈ s
⊢ ∀ ⦃x : ℝ⦄,
    x ∈ variationOnFromTo f s a '' s →
      ∀ ⦃y : ℝ⦄,
        y ∈ variationOnFromTo f s a '' s →
          x ≤ y →
            eVariationOn (naturalParameterization f s a) (variationOnFromTo f s a '' s ∩ Icc x y) =
              ENNReal.ofReal (↑1 * (y - x))
state_after: case intro.intro.intro.intro
α : Type u_1
inst✝¹ : LinearOrder α
E : Type u_2
inst✝ : PseudoEMetricSpace E
f✝ : ℝ → E
s✝ : Set ℝ
l : ℝ≥0
f : α → E
s : Set α
hf : LocallyBoundedVariationOn f s
a : α
as : a ∈ s
b : α
bs : b ∈ s
c : α
cs : c ∈ s
h : variationOnFromTo f s a b ≤ variationOnFromTo f s a c
⊢ eVariationOn (naturalParameterization f s a)
      (variationOnFromTo f s a '' s ∩ Icc (variationOnFromTo f s a b) (variationOnFromTo f s a c)) =
    ENNReal.ofReal (↑1 * (variationOnFromTo f s a c - variationOnFromTo f s a b))
tactic: rintro _ ⟨b, bs, rfl⟩ _ ⟨c, cs, rfl⟩ h
state_before: case intro.intro.intro.intro
α : Type u_1
inst✝¹ : LinearOrder α
E : Type u_2
inst✝ : PseudoEMetricSpace E
f✝ : ℝ → E
s✝ : Set ℝ
l : ℝ≥0
f : α → E
s : Set α
hf : LocallyBoundedVariationOn f s
a : α
as : a ∈ s
b : α
bs : b ∈ s
c : α
cs : c ∈ s
h : variationOnFromTo f s a b ≤ variationOnFromTo f s a c
⊢ eVariationOn (naturalParameterization f s a)
      (variationOnFromTo f s a '' s ∩ Icc (variationOnFromTo f s a b) (variationOnFromTo f s a c)) =
    ENNReal.ofReal (↑1 * (variationOnFromTo f s a c - variationOnFromTo f s a b))
state_after: case intro.intro.intro.intro.inl
α : Type u_1
inst✝¹ : LinearOrder α
E : Type u_2
inst✝ : PseudoEMetricSpace E
f✝ : ℝ → E
s✝ : Set ℝ
l : ℝ≥0
f : α → E
s : Set α
hf : LocallyBoundedVariationOn f s
a : α
as : a ∈ s
b : α
bs : b ∈ s
c : α
cs : c ∈ s
h : variationOnFromTo f s a b ≤ variationOnFromTo f s a c
cb : c ≤ b
⊢ eVariationOn (naturalParameterization f s a)
      (variationOnFromTo f s a '' s ∩ Icc (variationOnFromTo f s a b) (variationOnFromTo f s a c)) =
    ENNReal.ofReal (↑1 * (variationOnFromTo f s a c - variationOnFromTo f s a b))

case intro.intro.intro.intro.inr
α : Type u_1
inst✝¹ : LinearOrder α
E : Type u_2
inst✝ : PseudoEMetricSpace E
f✝ : ℝ → E
s✝ : Set ℝ
l : ℝ≥0
f : α → E
s : Set α
hf : LocallyBoundedVariationOn f s
a : α
as : a ∈ s
b : α
bs : b ∈ s
c : α
cs : c ∈ s
h : variationOnFromTo f s a b ≤ variationOnFromTo f s a c
bc : b ≤ c
⊢ eVariationOn (naturalParameterization f s a)
      (variationOnFromTo f s a '' s ∩ Icc (variationOnFromTo f s a b) (variationOnFromTo f s a c)) =
    ENNReal.ofReal (↑1 * (variationOnFromTo f s a c - variationOnFromTo f s a b))
tactic: rcases le_total c b with (cb | bc)