-- Mathlib/Probability/StrongLaw.lean
theorem sum_prob_mem_Ioc_le {X : Ω → ℝ} (hint : Integrable X) (hnonneg : 0 ≤ X) {K : ℕ} {N : ℕ}
    (hKN : K ≤ N) :
    ∑ j ∈ range K, ℙ {ω | X ω ∈ Set.Ioc (j : ℝ) N} ≤ ENNReal.ofReal (𝔼[X] + 1)

Proof state:
Ω : Type u_1
inst✝¹ : MeasureSpace Ω
inst✝ : IsProbabilityMeasure ℙ
X : Ω → ℝ
hint : Integrable X ℙ
hnonneg : 0 ≤ X
K N : ℕ
hKN : K ≤ N
ρ : Measure ℝ := Measure.map X ℙ
this : IsProbabilityMeasure ρ
A : ∑ j ∈ range K, ∫ (x : ℝ) in ↑j..↑N, 1 ∂ρ ≤ (∫ (a : Ω), X a) + 1
⊢ ∑ j ∈ range K, ℙ {ω | X ω ∈ Set.Ioc ↑j ↑N} ≤ ENNReal.ofReal ((∫ (a : Ω), X a) + 1)

Tactic:
have B : ∀ a b, ℙ {ω | X ω ∈ Set.Ioc a b} = ENNReal.ofReal (∫ _ in Set.Ioc a b, (1 : ℝ) ∂ρ) := by
  intro a b
  rw [ofReal_setIntegral_one ρ _,
    Measure.map_apply_of_aemeasurable hint.aemeasurable measurableSet_Ioc]
  rfl

Result:
Ω : Type u_1
inst✝¹ : MeasureSpace Ω
inst✝ : IsProbabilityMeasure ℙ
X : Ω → ℝ
hint : Integrable X ℙ
hnonneg : 0 ≤ X
K N : ℕ
hKN : K ≤ N
ρ : Measure ℝ := Measure.map X ℙ
this : IsProbabilityMeasure ρ
A : ∑ j ∈ range K, ∫ (x : ℝ) in ↑j..↑N, 1 ∂ρ ≤ (∫ (a : Ω), X a) + 1
B : ∀ (a b : ℝ), ℙ {ω | X ω ∈ Set.Ioc a b} = ENNReal.ofReal (∫ (x : ℝ) in Set.Ioc a b, 1 ∂ρ)
⊢ ∑ j ∈ range K, ℙ {ω | X ω ∈ Set.Ioc ↑j ↑N} ≤ ENNReal.ofReal ((∫ (a : Ω), X a) + 1)

Proof state:
Ω : Type u_1
inst✝¹ : MeasureSpace Ω
inst✝ : IsProbabilityMeasure ℙ
X : Ω → ℝ
hint : Integrable X ℙ
hnonneg : 0 ≤ X
K N : ℕ
hKN : K ≤ N
ρ : Measure ℝ := Measure.map X ℙ
this : IsProbabilityMeasure ρ
⊢ (ρ (Set.Ioc 0 ↑N)).toReal ≤ ENNReal.toReal 1

Tactic:
exact ENNReal.toReal_mono ENNReal.one_ne_top prob_le_one

Result:
no goals

Proof state:
Ω : Type u_1
inst✝¹ : MeasureSpace Ω
inst✝ : IsProbabilityMeasure ℙ
X : Ω → ℝ
hint : Integrable X ℙ
hnonneg : 0 ≤ X
K N : ℕ
hKN : K ≤ N
ρ : Measure ℝ := Measure.map X ℙ
this : IsProbabilityMeasure ρ
⊢ ∫ (x : ℝ) in 0 ..↑N, x ∂ρ + ∫ (x : ℝ) in 0 ..↑N, 1 ∂ρ = (∫ (a : Ω), truncation X (↑N) a) + ∫ (x : ℝ) in 0 ..↑N, 1 ∂ρ

Tactic:
rw [integral_truncation_eq_intervalIntegral_of_nonneg hint.1 hnonneg]

Result:
no goals

Proof state:
Ω : Type u_1
inst✝¹ : MeasureSpace Ω
inst✝ : IsProbabilityMeasure ℙ
X : Ω → ℝ
hint : Integrable X ℙ
hnonneg : 0 ≤ X
K N : ℕ
hKN : K ≤ N
ρ : Measure ℝ := Measure.map X ℙ
this : IsProbabilityMeasure ρ
i : ℕ
x✝ : i ∈ range N
⊢ ∑ j ∈ range ((i + 1) ⊓ K), ∫ (x : ℝ) in ↑i..↑(i + 1), 1 ∂ρ ≤ (↑i + 1) * ∫ (x : ℝ) in ↑i..↑(i + 1), 1 ∂ρ

Tactic:
simp only [Nat.cast_add, Nat.cast_one, sum_const, card_range, nsmul_eq_mul, Nat.cast_min]

Result:
Ω : Type u_1
inst✝¹ : MeasureSpace Ω
inst✝ : IsProbabilityMeasure ℙ
X : Ω → ℝ
hint : Integrable X ℙ
hnonneg : 0 ≤ X
K N : ℕ
hKN : K ≤ N
ρ : Measure ℝ := Measure.map X ℙ
this : IsProbabilityMeasure ρ
i : ℕ
x✝ : i ∈ range N
⊢ ((↑i + 1) ⊓ ↑K) * ∫ (x : ℝ) in ↑i..↑i + 1, 1 ∂ρ ≤ (↑i + 1) * ∫ (x : ℝ) in ↑i..↑i + 1, 1 ∂ρ

Proof state:
case e_r
Ω : Type u_1
inst✝¹ : MeasureSpace Ω
inst✝ : IsProbabilityMeasure ℙ
X : Ω → ℝ
hint : Integrable X ℙ
hnonneg : 0 ≤ X
K N : ℕ
hKN : K ≤ N
ρ : Measure ℝ := Measure.map X ℙ
this : IsProbabilityMeasure ρ
A : ∑ j ∈ range K, ∫ (x : ℝ) in ↑j..↑N, 1 ∂ρ ≤ (∫ (a : Ω), X a) + 1
B : ∀ (a b : ℝ), ℙ {ω | X ω ∈ Set.Ioc a b} = ENNReal.ofReal (∫ (x : ℝ) in Set.Ioc a b, 1 ∂ρ)
j : ℕ
hj : j ∈ range K
⊢ ∫ (x : ℝ) in Set.Ioc ↑j ↑N, 1 ∂ρ = ∫ (x : ℝ) in ↑j..↑N, 1 ∂ρ

Tactic:
rw [intervalIntegral.integral_of_le (Nat.cast_le.2 ((mem_range.1 hj).le.trans hKN))]

Result:
no goals

Proof state:
case hf
Ω : Type u_1
inst✝¹ : MeasureSpace Ω
inst✝ : IsProbabilityMeasure ℙ
X : Ω → ℝ
hint : Integrable X ℙ
hnonneg : 0 ≤ X
K N : ℕ
hKN : K ≤ N
ρ : Measure ℝ := Measure.map X ℙ
this : IsProbabilityMeasure ρ
i : ℕ
x✝ : i ∈ range N
⊢ ∀ u ∈ Set.Icc (↑i) (↑i + 1), 0 ≤ 1

Tactic:
simp only [zero_le_one, imp_true_iff]

Result:
no goals

Proof state:
case hg
Ω : Type u_1
inst✝¹ : MeasureSpace Ω
inst✝ : IsProbabilityMeasure ℙ
X : Ω → ℝ
hint : Integrable X ℙ
hnonneg : 0 ≤ X
K N : ℕ
hKN : K ≤ N
ρ : Measure ℝ := Measure.map X ℙ
this : IsProbabilityMeasure ρ
i : ℕ
x✝ : i ∈ range N
I : ↑i ≤ ↑(i + 1)
⊢ IntegrableOn (fun x => x + 1) (Set.Ioc ↑i ↑(i + 1)) ρ

Tactic:
exact (continuous_id.add continuous_const).integrableOn_Ioc

Result:
no goals

Proof state:
Ω : Type u_1
inst✝¹ : MeasureSpace Ω
inst✝ : IsProbabilityMeasure ℙ
X : Ω → ℝ
hint : Integrable X ℙ
hnonneg : 0 ≤ X
K N : ℕ
hKN : K ≤ N
ρ : Measure ℝ := Measure.map X ℙ
this : IsProbabilityMeasure ρ
⊢ ∑ i ∈ range N, ∑ j ∈ range ((i + 1) ⊓ K), ∫ (x : ℝ) in ↑i..↑(i + 1), 1 ∂ρ ≤
    ∑ i ∈ range N, (↑i + 1) * ∫ (x : ℝ) in ↑i..↑(i + 1), 1 ∂ρ

Tactic:
apply sum_le_sum fun i _ => ?_

Result:
Ω : Type u_1
inst✝¹ : MeasureSpace Ω
inst✝ : IsProbabilityMeasure ℙ
X : Ω → ℝ
hint : Integrable X ℙ
hnonneg : 0 ≤ X
K N : ℕ
hKN : K ≤ N
ρ : Measure ℝ := Measure.map X ℙ
this : IsProbabilityMeasure ρ
i : ℕ
x✝ : i ∈ range N
⊢ ∑ j ∈ range ((i + 1) ⊓ K), ∫ (x : ℝ) in ↑i..↑(i + 1), 1 ∂ρ ≤ (↑i + 1) * ∫ (x : ℝ) in ↑i..↑(i + 1), 1 ∂ρ

Proof state:
Ω : Type u_1
inst✝¹ : MeasureSpace Ω
inst✝ : IsProbabilityMeasure ℙ
X : Ω → ℝ
hint : Integrable X ℙ
hnonneg : 0 ≤ X
K N : ℕ
hKN : K ≤ N
ρ : Measure ℝ := Measure.map X ℙ
this : IsProbabilityMeasure ρ
i : ℕ
x✝ : i ∈ range N
⊢ ↑i ≤ ↑(i + 1)

Tactic:
simp only [Nat.cast_add, Nat.cast_one, le_add_iff_nonneg_right, zero_le_one]

Result:
no goals

Proof state:
Ω : Type u_1
inst✝¹ : MeasureSpace Ω
inst✝ : IsProbabilityMeasure ℙ
X : Ω → ℝ
hint : Integrable X ℙ
hnonneg : 0 ≤ X
K N : ℕ
hKN : K ≤ N
ρ : Measure ℝ := Measure.map X ℙ
this : IsProbabilityMeasure ρ
j : ℕ
hj : j ∈ range K
k : ℕ
a✝ : k ∈ Set.Ico j N
⊢ IntervalIntegrable (fun x => 1) ρ ↑k ↑(k + 1)

Tactic:
exact continuous_const.intervalIntegrable _ _

Result:
no goals

Proof state:
Ω : Type u_1
inst✝¹ : MeasureSpace Ω
inst✝ : IsProbabilityMeasure ℙ
X : Ω → ℝ
hint : Integrable X ℙ
hnonneg : 0 ≤ X
K N : ℕ
hKN : K ≤ N
ρ : Measure ℝ := Measure.map X ℙ
this : IsProbabilityMeasure ρ
A : ∑ j ∈ range K, ∫ (x : ℝ) in ↑j..↑N, 1 ∂ρ ≤ (∫ (a : Ω), X a) + 1
a b : ℝ
⊢ ℙ {ω | X ω ∈ Set.Ioc a b} = ENNReal.ofReal (∫ (x : ℝ) in Set.Ioc a b, 1 ∂ρ)

Tactic:
rw [ofReal_setIntegral_one ρ _,
  Measure.map_apply_of_aemeasurable hint.aemeasurable measurableSet_Ioc]

Result:
Ω : Type u_1
inst✝¹ : MeasureSpace Ω
inst✝ : IsProbabilityMeasure ℙ
X : Ω → ℝ
hint : Integrable X ℙ
hnonneg : 0 ≤ X
K N : ℕ
hKN : K ≤ N
ρ : Measure ℝ := Measure.map X ℙ
this : IsProbabilityMeasure ρ
A : ∑ j ∈ range K, ∫ (x : ℝ) in ↑j..↑N, 1 ∂ρ ≤ (∫ (a : Ω), X a) + 1
a b : ℝ
⊢ ℙ {ω | X ω ∈ Set.Ioc a b} = ℙ (X ⁻¹' Set.Ioc a b)

Proof state:
case hs
Ω : Type u_1
inst✝¹ : MeasureSpace Ω
inst✝ : IsProbabilityMeasure ℙ
X : Ω → ℝ
hint : Integrable X ℙ
hnonneg : 0 ≤ X
K N : ℕ
hKN : K ≤ N
ρ : Measure ℝ := Measure.map X ℙ
this : IsProbabilityMeasure ρ
i : ℕ
x✝ : i ∈ range N
I : ↑i ≤ ↑(i + 1)
⊢ MeasurableSet (Set.Ioc ↑i ↑(i + 1))

Tactic:
exact measurableSet_Ioc

Result:
no goals

Proof state:
Ω : Type u_1
inst✝¹ : MeasureSpace Ω
inst✝ : IsProbabilityMeasure ℙ
X : Ω → ℝ
hint : Integrable X ℙ
hnonneg : 0 ≤ X
K N : ℕ
hKN : K ≤ N
ρ : Measure ℝ := Measure.map X ℙ
this : IsProbabilityMeasure ρ
A : ∑ j ∈ range K, ∫ (x : ℝ) in ↑j..↑N, 1 ∂ρ ≤ (∫ (a : Ω), X a) + 1
⊢ ∀ (a b : ℝ), ℙ {ω | X ω ∈ Set.Ioc a b} = ENNReal.ofReal (∫ (x : ℝ) in Set.Ioc a b, 1 ∂ρ)

Tactic:
intro a b

Result:
Ω : Type u_1
inst✝¹ : MeasureSpace Ω
inst✝ : IsProbabilityMeasure ℙ
X : Ω → ℝ
hint : Integrable X ℙ
hnonneg : 0 ≤ X
K N : ℕ
hKN : K ≤ N
ρ : Measure ℝ := Measure.map X ℙ
this : IsProbabilityMeasure ρ
A : ∑ j ∈ range K, ∫ (x : ℝ) in ↑j..↑N, 1 ∂ρ ≤ (∫ (a : Ω), X a) + 1
a b : ℝ
⊢ ℙ {ω | X ω ∈ Set.Ioc a b} = ENNReal.ofReal (∫ (x : ℝ) in Set.Ioc a b, 1 ∂ρ)