Theorem: MeasureTheory.Measure.ext_of_Ico_finite
File: Mathlib/MeasureTheory/Constructions/BorelSpace/Order.lean

Proof steps:
state_before: α✝ : Type u_1
β : Type u_2
γ : Type u_3
δ : Type u_4
ι : Sort y
s t u : Set α✝
inst✝¹¹ : TopologicalSpace α✝
inst✝¹⁰ : MeasurableSpace α✝
inst✝⁹ : OpensMeasurableSpace α✝
inst✝⁸ : MeasurableSpace δ
inst✝⁷ : LinearOrder α✝
inst✝⁶ : OrderClosedTopology α✝
a b x : α✝
α : Type u_5
inst✝⁵ : TopologicalSpace α
m : MeasurableSpace α
inst✝⁴ : SecondCountableTopology α
inst✝³ : LinearOrder α
inst✝² : OrderTopology α
inst✝¹ : BorelSpace α
μ ν : Measure α
inst✝ : IsFiniteMeasure μ
hμν : μ univ = ν univ
h : ∀ ⦃a b : α⦄, a < b → μ (Ico a b) = ν (Ico a b)
⊢ μ = ν
state_after: α✝ : Type u_1
β : Type u_2
γ : Type u_3
δ : Type u_4
ι : Sort y
s t u : Set α✝
inst✝¹¹ : TopologicalSpace α✝
inst✝¹⁰ : MeasurableSpace α✝
inst✝⁹ : OpensMeasurableSpace α✝
inst✝⁸ : MeasurableSpace δ
inst✝⁷ : LinearOrder α✝
inst✝⁶ : OrderClosedTopology α✝
a b x : α✝
α : Type u_5
inst✝⁵ : TopologicalSpace α
m : MeasurableSpace α
inst✝⁴ : SecondCountableTopology α
inst✝³ : LinearOrder α
inst✝² : OrderTopology α
inst✝¹ : BorelSpace α
μ ν : Measure α
inst✝ : IsFiniteMeasure μ
hμν : μ univ = ν univ
h : ∀ ⦃a b : α⦄, a < b → μ (Ico a b) = ν (Ico a b)
⊢ ∀ s ∈ {S | ∃ l u, l < u ∧ Ico l u = S}, μ s = ν s
tactic: refine
    ext_of_generate_finite _ (BorelSpace.measurable_eq.trans (borel_eq_generateFrom_Ico α))
      (isPiSystem_Ico (id : α → α) id) ?_ hμν
state_before: α✝ : Type u_1
β : Type u_2
γ : Type u_3
δ : Type u_4
ι : Sort y
s t u : Set α✝
inst✝¹¹ : TopologicalSpace α✝
inst✝¹⁰ : MeasurableSpace α✝
inst✝⁹ : OpensMeasurableSpace α✝
inst✝⁸ : MeasurableSpace δ
inst✝⁷ : LinearOrder α✝
inst✝⁶ : OrderClosedTopology α✝
a b x : α✝
α : Type u_5
inst✝⁵ : TopologicalSpace α
m : MeasurableSpace α
inst✝⁴ : SecondCountableTopology α
inst✝³ : LinearOrder α
inst✝² : OrderTopology α
inst✝¹ : BorelSpace α
μ ν : Measure α
inst✝ : IsFiniteMeasure μ
hμν : μ univ = ν univ
h : ∀ ⦃a b : α⦄, a < b → μ (Ico a b) = ν (Ico a b)
⊢ ∀ s ∈ {S | ∃ l u, l < u ∧ Ico l u = S}, μ s = ν s
state_after: case intro.intro.intro
α✝ : Type u_1
β : Type u_2
γ : Type u_3
δ : Type u_4
ι : Sort y
s t u : Set α✝
inst✝¹¹ : TopologicalSpace α✝
inst✝¹⁰ : MeasurableSpace α✝
inst✝⁹ : OpensMeasurableSpace α✝
inst✝⁸ : MeasurableSpace δ
inst✝⁷ : LinearOrder α✝
inst✝⁶ : OrderClosedTopology α✝
a✝ b✝ x : α✝
α : Type u_5
inst✝⁵ : TopologicalSpace α
m : MeasurableSpace α
inst✝⁴ : SecondCountableTopology α
inst✝³ : LinearOrder α
inst✝² : OrderTopology α
inst✝¹ : BorelSpace α
μ ν : Measure α
inst✝ : IsFiniteMeasure μ
hμν : μ univ = ν univ
h : ∀ ⦃a b : α⦄, a < b → μ (Ico a b) = ν (Ico a b)
a b : α
hlt : a < b
⊢ μ (Ico a b) = ν (Ico a b)
tactic: rintro - ⟨a, b, hlt, rfl⟩
state_before: case intro.intro.intro
α✝ : Type u_1
β : Type u_2
γ : Type u_3
δ : Type u_4
ι : Sort y
s t u : Set α✝
inst✝¹¹ : TopologicalSpace α✝
inst✝¹⁰ : MeasurableSpace α✝
inst✝⁹ : OpensMeasurableSpace α✝
inst✝⁸ : MeasurableSpace δ
inst✝⁷ : LinearOrder α✝
inst✝⁶ : OrderClosedTopology α✝
a✝ b✝ x : α✝
α : Type u_5
inst✝⁵ : TopologicalSpace α
m : MeasurableSpace α
inst✝⁴ : SecondCountableTopology α
inst✝³ : LinearOrder α
inst✝² : OrderTopology α
inst✝¹ : BorelSpace α
μ ν : Measure α
inst✝ : IsFiniteMeasure μ
hμν : μ univ = ν univ
h : ∀ ⦃a b : α⦄, a < b → μ (Ico a b) = ν (Ico a b)
a b : α
hlt : a < b
⊢ μ (Ico a b) = ν (Ico a b)
state_after: no goals
tactic: exact h hlt