Theorem: AEMeasurable.subtype_mk
File: Mathlib/MeasureTheory/Measure/AEMeasurable.lean

tactic: nontriviality α
state_before: ι : Type u_1
α : Type u_2
β : Type u_3
γ : Type u_4
δ : Type u_5
R : Type u_6
m0 : MeasurableSpace α
inst✝² : MeasurableSpace β
inst✝¹ : MeasurableSpace γ
inst✝ : MeasurableSpace δ
f g : α → β
μ ν : Measure α
h : AEMeasurable f μ
s : Set β
hfs : ∀ (x : α), f x ∈ s
⊢ AEMeasurable (codRestrict f s hfs) μ
state_after: ι : Type u_1
α : Type u_2
β : Type u_3
γ : Type u_4
δ : Type u_5
R : Type u_6
m0 : MeasurableSpace α
inst✝² : MeasurableSpace β
inst✝¹ : MeasurableSpace γ
inst✝ : MeasurableSpace δ
f g : α → β
μ ν : Measure α
h : AEMeasurable f μ
s : Set β
hfs : ∀ (x : α), f x ∈ s
a✝ : Nontrivial α
⊢ AEMeasurable (codRestrict f s hfs) μ

tactic: inhabit α
state_before: ι : Type u_1
α : Type u_2
β : Type u_3
γ : Type u_4
δ : Type u_5
R : Type u_6
m0 : MeasurableSpace α
inst✝² : MeasurableSpace β
inst✝¹ : MeasurableSpace γ
inst✝ : MeasurableSpace δ
f g : α → β
μ ν : Measure α
h : AEMeasurable f μ
s : Set β
hfs : ∀ (x : α), f x ∈ s
a✝ : Nontrivial α
⊢ AEMeasurable (codRestrict f s hfs) μ
state_after: ι : Type u_1
α : Type u_2
β : Type u_3
γ : Type u_4
δ : Type u_5
R : Type u_6
m0 : MeasurableSpace α
inst✝² : MeasurableSpace β
inst✝¹ : MeasurableSpace γ
inst✝ : MeasurableSpace δ
f g : α → β
μ ν : Measure α
h : AEMeasurable f μ
s : Set β
hfs : ∀ (x : α), f x ∈ s
a✝ : Nontrivial α
inhabited_h : Inhabited α
⊢ AEMeasurable (codRestrict f s hfs) μ

tactic: obtain ⟨g, g_meas, hg, fg⟩ : ∃ g : α → β, Measurable g ∧ range g ⊆ s ∧ f =ᵐ[μ] g :=
  h.exists_ae_eq_range_subset (eventually_of_forall hfs) ⟨_, hfs default⟩
state_before: ι : Type u_1
α : Type u_2
β : Type u_3
γ : Type u_4
δ : Type u_5
R : Type u_6
m0 : MeasurableSpace α
inst✝² : MeasurableSpace β
inst✝¹ : MeasurableSpace γ
inst✝ : MeasurableSpace δ
f g : α → β
μ ν : Measure α
h : AEMeasurable f μ
s : Set β
hfs : ∀ (x : α), f x ∈ s
a✝ : Nontrivial α
inhabited_h : Inhabited α
⊢ AEMeasurable (codRestrict f s hfs) μ
state_after: case intro.intro.intro
ι : Type u_1
α : Type u_2
β : Type u_3
γ : Type u_4
δ : Type u_5
R : Type u_6
m0 : MeasurableSpace α
inst✝² : MeasurableSpace β
inst✝¹ : MeasurableSpace γ
inst✝ : MeasurableSpace δ
f g✝ : α → β
μ ν : Measure α
h : AEMeasurable f μ
s : Set β
hfs : ∀ (x : α), f x ∈ s
a✝ : Nontrivial α
inhabited_h : Inhabited α
g : α → β
g_meas : Measurable g
hg : range g ⊆ s
fg : f =ᶠ[ae μ] g
⊢ AEMeasurable (codRestrict f s hfs) μ

tactic: refine ⟨codRestrict g s fun x => hg (mem_range_self _), Measurable.subtype_mk g_meas, ?_⟩
state_before: case intro.intro.intro
ι : Type u_1
α : Type u_2
β : Type u_3
γ : Type u_4
δ : Type u_5
R : Type u_6
m0 : MeasurableSpace α
inst✝² : MeasurableSpace β
inst✝¹ : MeasurableSpace γ
inst✝ : MeasurableSpace δ
f g✝ : α → β
μ ν : Measure α
h : AEMeasurable f μ
s : Set β
hfs : ∀ (x : α), f x ∈ s
a✝ : Nontrivial α
inhabited_h : Inhabited α
g : α → β
g_meas : Measurable g
hg : range g ⊆ s
fg : f =ᶠ[ae μ] g
⊢ AEMeasurable (codRestrict f s hfs) μ
state_after: case intro.intro.intro
ι : Type u_1
α : Type u_2
β : Type u_3
γ : Type u_4
δ : Type u_5
R : Type u_6
m0 : MeasurableSpace α
inst✝² : MeasurableSpace β
inst✝¹ : MeasurableSpace γ
inst✝ : MeasurableSpace δ
f g✝ : α → β
μ ν : Measure α
h : AEMeasurable f μ
s : Set β
hfs : ∀ (x : α), f x ∈ s
a✝ : Nontrivial α
inhabited_h : Inhabited α
g : α → β
g_meas : Measurable g
hg : range g ⊆ s
fg : f =ᶠ[ae μ] g
⊢ codRestrict f s hfs =ᶠ[ae μ] codRestrict g s ⋯

tactic: filter_upwards [fg] with x hx
state_before: case intro.intro.intro
ι : Type u_1
α : Type u_2
β : Type u_3
γ : Type u_4
δ : Type u_5
R : Type u_6
m0 : MeasurableSpace α
inst✝² : MeasurableSpace β
inst✝¹ : MeasurableSpace γ
inst✝ : MeasurableSpace δ
f g✝ : α → β
μ ν : Measure α
h : AEMeasurable f μ
s : Set β
hfs : ∀ (x : α), f x ∈ s
a✝ : Nontrivial α
inhabited_h : Inhabited α
g : α → β
g_meas : Measurable g
hg : range g ⊆ s
fg : f =ᶠ[ae μ] g
⊢ codRestrict f s hfs =ᶠ[ae μ] codRestrict g s ⋯
state_after: case h
ι : Type u_1
α : Type u_2
β : Type u_3
γ : Type u_4
δ : Type u_5
R : Type u_6
m0 : MeasurableSpace α
inst✝² : MeasurableSpace β
inst✝¹ : MeasurableSpace γ
inst✝ : MeasurableSpace δ
f g✝ : α → β
μ ν : Measure α
h : AEMeasurable f μ
s : Set β
hfs : ∀ (x : α), f x ∈ s
a✝ : Nontrivial α
inhabited_h : Inhabited α
g : α → β
g_meas : Measurable g
hg : range g ⊆ s
fg : f =ᶠ[ae μ] g
x : α
hx : f x = g x
⊢ codRestrict f s hfs x = codRestrict g s ⋯ x

tactic: simpa [Subtype.ext_iff]
state_before: case h
ι : Type u_1
α : Type u_2
β : Type u_3
γ : Type u_4
δ : Type u_5
R : Type u_6
m0 : MeasurableSpace α
inst✝² : MeasurableSpace β
inst✝¹ : MeasurableSpace γ
inst✝ : MeasurableSpace δ
f g✝ : α → β
μ ν : Measure α
h : AEMeasurable f μ
s : Set β
hfs : ∀ (x : α), f x ∈ s
a✝ : Nontrivial α
inhabited_h : Inhabited α
g : α → β
g_meas : Measurable g
hg : range g ⊆ s
fg : f =ᶠ[ae μ] g
x : α
hx : f x = g x
⊢ codRestrict f s hfs x = codRestrict g s ⋯ x
state_after: no goals