-- Mathlib/MeasureTheory/Function/ConditionalExpectation/Indicator.lean
theorem condExp_ae_eq_restrict_of_measurableSpace_eq_on {m m₂ m0 : MeasurableSpace α}
    {μ : Measure α} (hm : m ≤ m0) (hm₂ : m₂ ≤ m0) [SigmaFinite (μ.trim hm)]
    [SigmaFinite (μ.trim hm₂)] (hs_m : MeasurableSet[m] s)
    (hs : ∀ t, MeasurableSet[m] (s ∩ t) ↔ MeasurableSet[m₂] (s ∩ t)) :
    μ[f|m] =ᵐ[μ.restrict s] μ[f|m₂]

Proof state:
case pos.refine_2
α : Type u_1
E : Type u_2
inst✝⁴ : NormedAddCommGroup E
inst✝³ : NormedSpace ℝ E
inst✝² : CompleteSpace E
f : α → E
s : Set α
m m₂ m0 : MeasurableSpace α
μ : Measure α
hm : m ≤ m0
hm₂ : m₂ ≤ m0
inst✝¹ : SigmaFinite (μ.trim hm)
inst✝ : SigmaFinite (μ.trim hm₂)
hs_m : MeasurableSet s
hs : ∀ (t : Set α), MeasurableSet (s ∩ t) ↔ MeasurableSet (s ∩ t)
hs_m₂ : MeasurableSet s
hf_int : Integrable f μ
this : StronglyMeasurable (μ[s.indicator f|m])
⊢ μ[s.indicator f|m] =ᶠ[ae (μ.restrict sᶜ)] 0

Tactic:
exact condExp_ae_eq_restrict_zero hs_m.compl (indicator_ae_eq_restrict_compl (hm _ hs_m))

Result:
no goals

Proof state:
case pos
α : Type u_1
E : Type u_2
inst✝⁴ : NormedAddCommGroup E
inst✝³ : NormedSpace ℝ E
inst✝² : CompleteSpace E
f : α → E
s : Set α
m m₂ m0 : MeasurableSpace α
μ : Measure α
hm : m ≤ m0
hm₂ : m₂ ≤ m0
inst✝¹ : SigmaFinite (μ.trim hm)
inst✝ : SigmaFinite (μ.trim hm₂)
hs_m : MeasurableSet s
hs : ∀ (t : Set α), MeasurableSet (s ∩ t) ↔ MeasurableSet (s ∩ t)
hs_m₂ : MeasurableSet s
hf_int : Integrable f μ
⊢ s.indicator (μ[f|m]) =ᶠ[ae μ] s.indicator (μ[f|m₂])

Tactic:
refine ((condExp_indicator hf_int hs_m).symm.trans ?_).trans (condExp_indicator hf_int hs_m₂)

Result:
case pos
α : Type u_1
E : Type u_2
inst✝⁴ : NormedAddCommGroup E
inst✝³ : NormedSpace ℝ E
inst✝² : CompleteSpace E
f : α → E
s : Set α
m m₂ m0 : MeasurableSpace α
μ : Measure α
hm : m ≤ m0
hm₂ : m₂ ≤ m0
inst✝¹ : SigmaFinite (μ.trim hm)
inst✝ : SigmaFinite (μ.trim hm₂)
hs_m : MeasurableSet s
hs : ∀ (t : Set α), MeasurableSet (s ∩ t) ↔ MeasurableSet (s ∩ t)
hs_m₂ : MeasurableSet s
hf_int : Integrable f μ
⊢ μ[s.indicator f|m] =ᶠ[ae μ] μ[s.indicator f|m₂]

Proof state:
α : Type u_1
E : Type u_2
inst✝⁴ : NormedAddCommGroup E
inst✝³ : NormedSpace ℝ E
inst✝² : CompleteSpace E
f : α → E
s : Set α
m m₂ m0 : MeasurableSpace α
μ : Measure α
hm : m ≤ m0
hm₂ : m₂ ≤ m0
inst✝¹ : SigmaFinite (μ.trim hm)
inst✝ : SigmaFinite (μ.trim hm₂)
hs_m : MeasurableSet s
hs : ∀ (t : Set α), MeasurableSet (s ∩ t) ↔ MeasurableSet (s ∩ t)
⊢ μ[f|m] =ᶠ[ae (μ.restrict s)] μ[f|m₂]

Tactic:
rw [ae_eq_restrict_iff_indicator_ae_eq (hm _ hs_m)]

Result:
α : Type u_1
E : Type u_2
inst✝⁴ : NormedAddCommGroup E
inst✝³ : NormedSpace ℝ E
inst✝² : CompleteSpace E
f : α → E
s : Set α
m m₂ m0 : MeasurableSpace α
μ : Measure α
hm : m ≤ m0
hm₂ : m₂ ≤ m0
inst✝¹ : SigmaFinite (μ.trim hm)
inst✝ : SigmaFinite (μ.trim hm₂)
hs_m : MeasurableSet s
hs : ∀ (t : Set α), MeasurableSet (s ∩ t) ↔ MeasurableSet (s ∩ t)
⊢ s.indicator (μ[f|m]) =ᶠ[ae μ] s.indicator (μ[f|m₂])

Proof state:
case pos.refine_1
α : Type u_1
E : Type u_2
inst✝⁴ : NormedAddCommGroup E
inst✝³ : NormedSpace ℝ E
inst✝² : CompleteSpace E
f : α → E
s : Set α
m m₂ m0 : MeasurableSpace α
μ : Measure α
hm : m ≤ m0
hm₂ : m₂ ≤ m0
inst✝¹ : SigmaFinite (μ.trim hm)
inst✝ : SigmaFinite (μ.trim hm₂)
hs_m : MeasurableSet s
hs : ∀ (t : Set α), MeasurableSet (s ∩ t) ↔ MeasurableSet (s ∩ t)
hs_m₂ : MeasurableSet s
hf_int : Integrable f μ
⊢ ∀ (s_1 : Set α),
    MeasurableSet s_1 →
      μ s_1 < ⊤ → ∫ (x : α) in s_1, (μ[s.indicator f|m]) x ∂μ = ∫ (x : α) in s_1, (μ[s.indicator f|m₂]) x ∂μ

case pos.refine_2
α : Type u_1
E : Type u_2
inst✝⁴ : NormedAddCommGroup E
inst✝³ : NormedSpace ℝ E
inst✝² : CompleteSpace E
f : α → E
s : Set α
m m₂ m0 : MeasurableSpace α
μ : Measure α
hm : m ≤ m0
hm₂ : m₂ ≤ m0
inst✝¹ : SigmaFinite (μ.trim hm)
inst✝ : SigmaFinite (μ.trim hm₂)
hs_m : MeasurableSet s
hs : ∀ (t : Set α), MeasurableSet (s ∩ t) ↔ MeasurableSet (s ∩ t)
hs_m₂ : MeasurableSet s
hf_int : Integrable f μ
⊢ AEStronglyMeasurable (μ[s.indicator f|m]) μ

Tactic:
swap

Result:
case pos.refine_2
α : Type u_1
E : Type u_2
inst✝⁴ : NormedAddCommGroup E
inst✝³ : NormedSpace ℝ E
inst✝² : CompleteSpace E
f : α → E
s : Set α
m m₂ m0 : MeasurableSpace α
μ : Measure α
hm : m ≤ m0
hm₂ : m₂ ≤ m0
inst✝¹ : SigmaFinite (μ.trim hm)
inst✝ : SigmaFinite (μ.trim hm₂)
hs_m : MeasurableSet s
hs : ∀ (t : Set α), MeasurableSet (s ∩ t) ↔ MeasurableSet (s ∩ t)
hs_m₂ : MeasurableSet s
hf_int : Integrable f μ
⊢ AEStronglyMeasurable (μ[s.indicator f|m]) μ

case pos.refine_1
α : Type u_1
E : Type u_2
inst✝⁴ : NormedAddCommGroup E
inst✝³ : NormedSpace ℝ E
inst✝² : CompleteSpace E
f : α → E
s : Set α
m m₂ m0 : MeasurableSpace α
μ : Measure α
hm : m ≤ m0
hm₂ : m₂ ≤ m0
inst✝¹ : SigmaFinite (μ.trim hm)
inst✝ : SigmaFinite (μ.trim hm₂)
hs_m : MeasurableSet s
hs : ∀ (t : Set α), MeasurableSet (s ∩ t) ↔ MeasurableSet (s ∩ t)
hs_m₂ : MeasurableSet s
hf_int : Integrable f μ
⊢ ∀ (s_1 : Set α),
    MeasurableSet s_1 →
      μ s_1 < ⊤ → ∫ (x : α) in s_1, (μ[s.indicator f|m]) x ∂μ = ∫ (x : α) in s_1, (μ[s.indicator f|m₂]) x ∂μ

Proof state:
α : Type u_1
E : Type u_2
inst✝⁴ : NormedAddCommGroup E
inst✝³ : NormedSpace ℝ E
inst✝² : CompleteSpace E
f : α → E
s : Set α
m m₂ m0 : MeasurableSpace α
μ : Measure α
hm : m ≤ m0
hm₂ : m₂ ≤ m0
inst✝¹ : SigmaFinite (μ.trim hm)
inst✝ : SigmaFinite (μ.trim hm₂)
hs_m : MeasurableSet s
hs : ∀ (t : Set α), MeasurableSet (s ∩ t) ↔ MeasurableSet (s ∩ t)
hs_m₂ : MeasurableSet s
hf_int : Integrable f μ
t : Set α
ht : MeasurableSet t
a✝ : μ t < ⊤
⊢ μ[s.indicator f|m] =ᶠ[ae (μ.restrict sᶜ)] 0

Tactic:
refine condExp_ae_eq_restrict_zero hs_m.compl ?_

Result:
α : Type u_1
E : Type u_2
inst✝⁴ : NormedAddCommGroup E
inst✝³ : NormedSpace ℝ E
inst✝² : CompleteSpace E
f : α → E
s : Set α
m m₂ m0 : MeasurableSpace α
μ : Measure α
hm : m ≤ m0
hm₂ : m₂ ≤ m0
inst✝¹ : SigmaFinite (μ.trim hm)
inst✝ : SigmaFinite (μ.trim hm₂)
hs_m : MeasurableSet s
hs : ∀ (t : Set α), MeasurableSet (s ∩ t) ↔ MeasurableSet (s ∩ t)
hs_m₂ : MeasurableSet s
hf_int : Integrable f μ
t : Set α
ht : MeasurableSet t
a✝ : μ t < ⊤
⊢ s.indicator f =ᶠ[ae (μ.restrict sᶜ)] 0

Proof state:
case pos.refine_2
α : Type u_1
E : Type u_2
inst✝⁴ : NormedAddCommGroup E
inst✝³ : NormedSpace ℝ E
inst✝² : CompleteSpace E
f : α → E
s : Set α
m m₂ m0 : MeasurableSpace α
μ : Measure α
hm : m ≤ m0
hm₂ : m₂ ≤ m0
inst✝¹ : SigmaFinite (μ.trim hm)
inst✝ : SigmaFinite (μ.trim hm₂)
hs_m : MeasurableSet s
hs : ∀ (t : Set α), MeasurableSet (s ∩ t) ↔ MeasurableSet (s ∩ t)
hs_m₂ : MeasurableSet s
hf_int : Integrable f μ
⊢ AEStronglyMeasurable (μ[s.indicator f|m]) μ

Tactic:
have : StronglyMeasurable[m] (μ[s.indicator f|m]) := stronglyMeasurable_condExp

Result:
case pos.refine_2
α : Type u_1
E : Type u_2
inst✝⁴ : NormedAddCommGroup E
inst✝³ : NormedSpace ℝ E
inst✝² : CompleteSpace E
f : α → E
s : Set α
m m₂ m0 : MeasurableSpace α
μ : Measure α
hm : m ≤ m0
hm₂ : m₂ ≤ m0
inst✝¹ : SigmaFinite (μ.trim hm)
inst✝ : SigmaFinite (μ.trim hm₂)
hs_m : MeasurableSet s
hs : ∀ (t : Set α), MeasurableSet (s ∩ t) ↔ MeasurableSet (s ∩ t)
hs_m₂ : MeasurableSet s
hf_int : Integrable f μ
this : StronglyMeasurable (μ[s.indicator f|m])
⊢ AEStronglyMeasurable (μ[s.indicator f|m]) μ