-- File: FoML/FoML/Rademacher.lean
Theorem statement:
theorem extracted_formal_statement_273.{u_1, w, u} {Ω : Type u} [inst : MeasurableSpace Ω] {Z : Type w} {n : ℕ}
  {ι : Type u_1} {f : ι → Z → ℝ} {μ : Measure Ω} [inst_1 : IsProbabilityMeasure μ] [inst_2 : Nonempty ι]
  [inst_3 : Countable ι] {X : Ω → Z} (hf : ∀ (i : ι), Measurable (f i ∘ X)) {b : ℝ}
  (hf' : ∀ (i : ι) (z : Z), |f i z| ≤ b) (ω : (Fin n → Ω) × (Fin n → Ω)) (σ : Signs n) (a : σ ∈ Finset.univ)
  (h_original_goal : |⨆ i, |∑ k, ↑↑(σ k) * f i (X (ω.1 k))|| ≤ ⨆ i, |∑ k, ↑↑(σ k) * f i (X (ω.1 k))|) (i : ι) :
  |(|∑ k, ↑↑(σ k) * f i (X (ω.1 k))|)| ≤ ⨆ i, |∑ k, ↑↑(σ k) * f i (X (ω.1 k))| := sorry

Tactic state before:
case h
Ω : Type u
inst✝³ : MeasurableSpace Ω
Z : Type w
n : ℕ
ι : Type u_1
f : ι → Z → ℝ
μ : Measure Ω
inst✝² : IsProbabilityMeasure μ
inst✝¹ : Nonempty ι
inst✝ : Countable ι
X : Ω → Z
hf : ∀ (i : ι), Measurable (f i ∘ X)
b : ℝ
hf' : ∀ (i : ι) (z : Z), |f i z| ≤ b
ω : (Fin n → Ω) × (Fin n → Ω)
σ : Signs n
a✝ : σ ∈ Finset.univ
⊢ |⨆ i, |∑ k, ↑↑(σ k) * f i (X (ω.1 k))|| ≤ ⨆ i, |∑ k, ↑↑(σ k) * f i (X (ω.1 k))|

Tactic: apply abs_iSup_le

Tactic state after:
[case h.hf
 Ω : Type u
 inst✝³ : MeasurableSpace Ω
 Z : Type w
 n : ℕ
 ι : Type u_1
 f : ι → Z → ℝ
 μ : Measure Ω
 inst✝² : IsProbabilityMeasure μ
 inst✝¹ : Nonempty ι
 inst✝ : Countable ι
 X : Ω → Z
 hf : ∀ (i : ι), Measurable (f i ∘ X)
 b : ℝ
 hf' : ∀ (i : ι) (z : Z), |f i z| ≤ b
 ω : (Fin n → Ω) × (Fin n → Ω)
 σ : Signs n
 a✝ : σ ∈ Finset.univ
 ⊢ ∀ (i : ι), |(|∑ k, ↑↑(σ k) * f i (X (ω.1 k))|)| ≤ ⨆ i, |∑ k, ↑↑(σ k) * f i (X (ω.1 k))|]

Premises used:
abs_iSup_le : ∀ {ι : Type v} [inst : Nonempty ι] {f : ι → ℝ} {a : ℝ}, (∀ (i : ι), |f i| ≤ a) → |⨆ i, f i| ≤ a