Theorem: MeasureTheory.borel_eq_borel_of_le
File: Mathlib/MeasureTheory/Constructions/Polish/Basic.lean

Proof steps:
state_before: α✝ : Type u_1
ι : Type u_2
γ : Type u_3
α : Type u_4
β : Type u_5
tβ : TopologicalSpace β
inst✝² : T2Space β
inst✝¹ : MeasurableSpace β
inst✝ : MeasurableSpace α
s : Set γ
f : γ → β
t t' : TopologicalSpace γ
ht : PolishSpace γ
ht' : PolishSpace γ
hle : t ≤ t'
⊢ borel γ = borel γ
state_after: α✝ : Type u_1
ι : Type u_2
γ : Type u_3
α : Type u_4
β : Type u_5
tβ : TopologicalSpace β
inst✝² : T2Space β
inst✝¹ : MeasurableSpace β
inst✝ : MeasurableSpace α
s : Set γ
f : γ → β
t t' : TopologicalSpace γ
ht : PolishSpace γ
ht' : PolishSpace γ
hle : t ≤ t'
⊢ borel γ ≤ borel γ
tactic: refine le_antisymm ?_ (borel_anti hle)
state_before: α✝ : Type u_1
ι : Type u_2
γ : Type u_3
α : Type u_4
β : Type u_5
tβ : TopologicalSpace β
inst✝² : T2Space β
inst✝¹ : MeasurableSpace β
inst✝ : MeasurableSpace α
s : Set γ
f : γ → β
t t' : TopologicalSpace γ
ht : PolishSpace γ
ht' : PolishSpace γ
hle : t ≤ t'
⊢ borel γ ≤ borel γ
state_after: α✝ : Type u_1
ι : Type u_2
γ : Type u_3
α : Type u_4
β : Type u_5
tβ : TopologicalSpace β
inst✝² : T2Space β
inst✝¹ : MeasurableSpace β
inst✝ : MeasurableSpace α
s✝ : Set γ
f : γ → β
t t' : TopologicalSpace γ
ht : PolishSpace γ
ht' : PolishSpace γ
hle : t ≤ t'
s : Set γ
hs : MeasurableSet s
⊢ MeasurableSet s
tactic: intro s hs
state_before: α✝ : Type u_1
ι : Type u_2
γ : Type u_3
α : Type u_4
β : Type u_5
tβ : TopologicalSpace β
inst✝² : T2Space β
inst✝¹ : MeasurableSpace β
inst✝ : MeasurableSpace α
s✝ : Set γ
f : γ → β
t t' : TopologicalSpace γ
ht : PolishSpace γ
ht' : PolishSpace γ
hle : t ≤ t'
s : Set γ
hs : MeasurableSet s
⊢ MeasurableSet s
state_after: α✝ : Type u_1
ι : Type u_2
γ : Type u_3
α : Type u_4
β : Type u_5
tβ : TopologicalSpace β
inst✝² : T2Space β
inst✝¹ : MeasurableSpace β
inst✝ : MeasurableSpace α
s✝ : Set γ
f : γ → β
t t' : TopologicalSpace γ
ht : PolishSpace γ
ht' : PolishSpace γ
hle : t ≤ t'
s : Set γ
hs : MeasurableSet s
e : MeasurableEmbedding id
⊢ MeasurableSet s
tactic: have e := @Continuous.measurableEmbedding
    _ _ t' _ (@borel _ t') _ (@BorelSpace.mk _ _ (borel γ) rfl)
    t _ (@borel _ t) (@BorelSpace.mk _ t (@borel _ t) rfl) (continuous_id_of_le hle) injective_id
state_before: α✝ : Type u_1
ι : Type u_2
γ : Type u_3
α : Type u_4
β : Type u_5
tβ : TopologicalSpace β
inst✝² : T2Space β
inst✝¹ : MeasurableSpace β
inst✝ : MeasurableSpace α
s✝ : Set γ
f : γ → β
t t' : TopologicalSpace γ
ht : PolishSpace γ
ht' : PolishSpace γ
hle : t ≤ t'
s : Set γ
hs : MeasurableSet s
e : MeasurableEmbedding id
⊢ MeasurableSet s
state_after: case h.e'_3
α✝ : Type u_1
ι : Type u_2
γ : Type u_3
α : Type u_4
β : Type u_5
tβ : TopologicalSpace β
inst✝² : T2Space β
inst✝¹ : MeasurableSpace β
inst✝ : MeasurableSpace α
s✝ : Set γ
f : γ → β
t t' : TopologicalSpace γ
ht : PolishSpace γ
ht' : PolishSpace γ
hle : t ≤ t'
s : Set γ
hs : MeasurableSet s
e : MeasurableEmbedding id
⊢ s = id '' s
tactic: convert e.measurableSet_image.2 hs
state_before: case h.e'_3
α✝ : Type u_1
ι : Type u_2
γ : Type u_3
α : Type u_4
β : Type u_5
tβ : TopologicalSpace β
inst✝² : T2Space β
inst✝¹ : MeasurableSpace β
inst✝ : MeasurableSpace α
s✝ : Set γ
f : γ → β
t t' : TopologicalSpace γ
ht : PolishSpace γ
ht' : PolishSpace γ
hle : t ≤ t'
s : Set γ
hs : MeasurableSet s
e : MeasurableEmbedding id
⊢ s = id '' s
state_after: no goals
tactic: simp only [id_eq, image_id']