-- Mathlib/MeasureTheory/Function/StronglyMeasurable/Basic.lean
theorem _root_.Measurable.stronglyMeasurable [TopologicalSpace β] [PseudoMetrizableSpace β]
    [SecondCountableTopology β] [OpensMeasurableSpace β] (hf : Measurable f) :
    StronglyMeasurable f

Proof state:
α : Type u_1
β : Type u_2
f : α → β
mα : MeasurableSpace α
inst✝⁴ : MeasurableSpace β
inst✝³ : TopologicalSpace β
inst✝² : PseudoMetrizableSpace β
inst✝¹ : SecondCountableTopology β
inst✝ : OpensMeasurableSpace β
hf : Measurable f
this : PseudoMetricSpace β := pseudoMetrizableSpacePseudoMetric β
a✝ : Nontrivial β
inhabited_h : Inhabited β
⊢ StronglyMeasurable f

Tactic:
exact ⟨SimpleFunc.approxOn f hf Set.univ default (Set.mem_univ _), fun x ↦
  SimpleFunc.tendsto_approxOn hf (Set.mem_univ _) (by rw [closure_univ]; simp)⟩

Result:
no goals

Proof state:
α : Type u_1
β : Type u_2
f : α → β
mα : MeasurableSpace α
inst✝⁴ : MeasurableSpace β
inst✝³ : TopologicalSpace β
inst✝² : PseudoMetrizableSpace β
inst✝¹ : SecondCountableTopology β
inst✝ : OpensMeasurableSpace β
hf : Measurable f
this : PseudoMetricSpace β := pseudoMetrizableSpacePseudoMetric β
a✝ : Nontrivial β
inhabited_h : Inhabited β
x : α
⊢ f x ∈ univ

Tactic:
simp

Result:
no goals

Proof state:
α : Type u_1
β : Type u_2
f : α → β
mα : MeasurableSpace α
inst✝⁴ : MeasurableSpace β
inst✝³ : TopologicalSpace β
inst✝² : PseudoMetrizableSpace β
inst✝¹ : SecondCountableTopology β
inst✝ : OpensMeasurableSpace β
hf : Measurable f
this : PseudoMetricSpace β := pseudoMetrizableSpacePseudoMetric β
a✝ : Nontrivial β
⊢ StronglyMeasurable f

Tactic:
inhabit β

Result:
α : Type u_1
β : Type u_2
f : α → β
mα : MeasurableSpace α
inst✝⁴ : MeasurableSpace β
inst✝³ : TopologicalSpace β
inst✝² : PseudoMetrizableSpace β
inst✝¹ : SecondCountableTopology β
inst✝ : OpensMeasurableSpace β
hf : Measurable f
this : PseudoMetricSpace β := pseudoMetrizableSpacePseudoMetric β
a✝ : Nontrivial β
inhabited_h : Inhabited β
⊢ StronglyMeasurable f

Proof state:
α : Type u_1
β : Type u_2
f : α → β
mα : MeasurableSpace α
inst✝⁴ : MeasurableSpace β
inst✝³ : TopologicalSpace β
inst✝² : PseudoMetrizableSpace β
inst✝¹ : SecondCountableTopology β
inst✝ : OpensMeasurableSpace β
hf : Measurable f
this : PseudoMetricSpace β := pseudoMetrizableSpacePseudoMetric β
⊢ StronglyMeasurable f

Tactic:
nontriviality β

Result:
α : Type u_1
β : Type u_2
f : α → β
mα : MeasurableSpace α
inst✝⁴ : MeasurableSpace β
inst✝³ : TopologicalSpace β
inst✝² : PseudoMetrizableSpace β
inst✝¹ : SecondCountableTopology β
inst✝ : OpensMeasurableSpace β
hf : Measurable f
this : PseudoMetricSpace β := pseudoMetrizableSpacePseudoMetric β
a✝ : Nontrivial β
⊢ StronglyMeasurable f

Proof state:
α : Type u_1
β : Type u_2
f : α → β
mα : MeasurableSpace α
inst✝⁴ : MeasurableSpace β
inst✝³ : TopologicalSpace β
inst✝² : PseudoMetrizableSpace β
inst✝¹ : SecondCountableTopology β
inst✝ : OpensMeasurableSpace β
hf : Measurable f
⊢ StronglyMeasurable f

Tactic:
letI := pseudoMetrizableSpacePseudoMetric β

Result:
α : Type u_1
β : Type u_2
f : α → β
mα : MeasurableSpace α
inst✝⁴ : MeasurableSpace β
inst✝³ : TopologicalSpace β
inst✝² : PseudoMetrizableSpace β
inst✝¹ : SecondCountableTopology β
inst✝ : OpensMeasurableSpace β
hf : Measurable f
this : PseudoMetricSpace β := pseudoMetrizableSpacePseudoMetric β
⊢ StronglyMeasurable f

Proof state:
α : Type u_1
β : Type u_2
f : α → β
mα : MeasurableSpace α
inst✝⁴ : MeasurableSpace β
inst✝³ : TopologicalSpace β
inst✝² : PseudoMetrizableSpace β
inst✝¹ : SecondCountableTopology β
inst✝ : OpensMeasurableSpace β
hf : Measurable f
this : PseudoMetricSpace β := pseudoMetrizableSpacePseudoMetric β
a✝ : Nontrivial β
inhabited_h : Inhabited β
x : α
⊢ f x ∈ closure univ

Tactic:
rw [closure_univ]

Result:
α : Type u_1
β : Type u_2
f : α → β
mα : MeasurableSpace α
inst✝⁴ : MeasurableSpace β
inst✝³ : TopologicalSpace β
inst✝² : PseudoMetrizableSpace β
inst✝¹ : SecondCountableTopology β
inst✝ : OpensMeasurableSpace β
hf : Measurable f
this : PseudoMetricSpace β := pseudoMetrizableSpacePseudoMetric β
a✝ : Nontrivial β
inhabited_h : Inhabited β
x : α
⊢ f x ∈ univ