-- Mathlib/MeasureTheory/Integral/Lebesgue.lean
theorem univ_le_of_forall_fin_meas_le {μ : Measure α} (hm : m ≤ m0) [SigmaFinite (μ.trim hm)]
    (C : ℝ≥0∞) {f : Set α → ℝ≥0∞} (hf : ∀ s, MeasurableSet[m] s → μ s ≠ ∞ → f s ≤ C)
    (h_F_lim :
      ∀ S : ℕ → Set α, (∀ n, MeasurableSet[m] (S n)) → Monotone S → f (⋃ n, S n) ≤ ⨆ n, f (S n)) :
    f univ ≤ C

Proof state:
α : Type u_1
m m0 : MeasurableSpace α
μ : Measure α
hm : m ≤ m0
inst✝ : SigmaFinite (μ.trim hm)
C : ℝ≥0∞
f : Set α → ℝ≥0∞
hf : ∀ (s : Set α), MeasurableSet s → μ s ≠ ⊤ → f s ≤ C
h_F_lim : ∀ (S : ℕ → Set α), (∀ (n : ℕ), MeasurableSet (S n)) → Monotone S → f (⋃ n, S n) ≤ ⨆ n, f (S n)
S : ℕ → Set α := spanningSets (μ.trim hm)
hS_mono : Monotone S
hS_meas : ∀ (n : ℕ), MeasurableSet (S n)
⊢ f univ ≤ C

Tactic:
rw [← @iUnion_spanningSets _ m (μ.trim hm)]

Result:
α : Type u_1
m m0 : MeasurableSpace α
μ : Measure α
hm : m ≤ m0
inst✝ : SigmaFinite (μ.trim hm)
C : ℝ≥0∞
f : Set α → ℝ≥0∞
hf : ∀ (s : Set α), MeasurableSet s → μ s ≠ ⊤ → f s ≤ C
h_F_lim : ∀ (S : ℕ → Set α), (∀ (n : ℕ), MeasurableSet (S n)) → Monotone S → f (⋃ n, S n) ≤ ⨆ n, f (S n)
S : ℕ → Set α := spanningSets (μ.trim hm)
hS_mono : Monotone S
hS_meas : ∀ (n : ℕ), MeasurableSet (S n)
⊢ f (⋃ i, spanningSets (μ.trim hm) i) ≤ C

Proof state:
α : Type u_1
m m0 : MeasurableSpace α
μ : Measure α
hm : m ≤ m0
inst✝ : SigmaFinite (μ.trim hm)
C : ℝ≥0∞
f : Set α → ℝ≥0∞
hf : ∀ (s : Set α), MeasurableSet s → μ s ≠ ⊤ → f s ≤ C
h_F_lim : ∀ (S : ℕ → Set α), (∀ (n : ℕ), MeasurableSet (S n)) → Monotone S → f (⋃ n, S n) ≤ ⨆ n, f (S n)
⊢ f univ ≤ C

Tactic:
let S := @spanningSets _ m (μ.trim hm) _

Result:
α : Type u_1
m m0 : MeasurableSpace α
μ : Measure α
hm : m ≤ m0
inst✝ : SigmaFinite (μ.trim hm)
C : ℝ≥0∞
f : Set α → ℝ≥0∞
hf : ∀ (s : Set α), MeasurableSet s → μ s ≠ ⊤ → f s ≤ C
h_F_lim : ∀ (S : ℕ → Set α), (∀ (n : ℕ), MeasurableSet (S n)) → Monotone S → f (⋃ n, S n) ≤ ⨆ n, f (S n)
S : ℕ → Set α := spanningSets (μ.trim hm)
⊢ f univ ≤ C

Proof state:
α : Type u_1
m m0 : MeasurableSpace α
μ : Measure α
hm : m ≤ m0
inst✝ : SigmaFinite (μ.trim hm)
C : ℝ≥0∞
f : Set α → ℝ≥0∞
hf : ∀ (s : Set α), MeasurableSet s → μ s ≠ ⊤ → f s ≤ C
h_F_lim : ∀ (S : ℕ → Set α), (∀ (n : ℕ), MeasurableSet (S n)) → Monotone S → f (⋃ n, S n) ≤ ⨆ n, f (S n)
S : ℕ → Set α := spanningSets (μ.trim hm)
hS_mono : Monotone S
hS_meas : ∀ (n : ℕ), MeasurableSet (S n)
⊢ ⨆ n, f (S n) ≤ C

Tactic:
refine iSup_le fun n => hf (S n) (hS_meas n) ?_

Result:
α : Type u_1
m m0 : MeasurableSpace α
μ : Measure α
hm : m ≤ m0
inst✝ : SigmaFinite (μ.trim hm)
C : ℝ≥0∞
f : Set α → ℝ≥0∞
hf : ∀ (s : Set α), MeasurableSet s → μ s ≠ ⊤ → f s ≤ C
h_F_lim : ∀ (S : ℕ → Set α), (∀ (n : ℕ), MeasurableSet (S n)) → Monotone S → f (⋃ n, S n) ≤ ⨆ n, f (S n)
S : ℕ → Set α := spanningSets (μ.trim hm)
hS_mono : Monotone S
hS_meas : ∀ (n : ℕ), MeasurableSet (S n)
n : ℕ
⊢ μ (S n) ≠ ⊤

Proof state:
α : Type u_1
m m0 : MeasurableSpace α
μ : Measure α
hm : m ≤ m0
inst✝ : SigmaFinite (μ.trim hm)
C : ℝ≥0∞
f : Set α → ℝ≥0∞
hf : ∀ (s : Set α), MeasurableSet s → μ s ≠ ⊤ → f s ≤ C
h_F_lim : ∀ (S : ℕ → Set α), (∀ (n : ℕ), MeasurableSet (S n)) → Monotone S → f (⋃ n, S n) ≤ ⨆ n, f (S n)
S : ℕ → Set α := spanningSets (μ.trim hm)
hS_mono : Monotone S
⊢ f univ ≤ C

Tactic:
have hS_meas : ∀ n, MeasurableSet[m] (S n) := @measurableSet_spanningSets _ m (μ.trim hm) _

Result:
α : Type u_1
m m0 : MeasurableSpace α
μ : Measure α
hm : m ≤ m0
inst✝ : SigmaFinite (μ.trim hm)
C : ℝ≥0∞
f : Set α → ℝ≥0∞
hf : ∀ (s : Set α), MeasurableSet s → μ s ≠ ⊤ → f s ≤ C
h_F_lim : ∀ (S : ℕ → Set α), (∀ (n : ℕ), MeasurableSet (S n)) → Monotone S → f (⋃ n, S n) ≤ ⨆ n, f (S n)
S : ℕ → Set α := spanningSets (μ.trim hm)
hS_mono : Monotone S
hS_meas : ∀ (n : ℕ), MeasurableSet (S n)
⊢ f univ ≤ C

Proof state:
α : Type u_1
m m0 : MeasurableSpace α
μ : Measure α
hm : m ≤ m0
inst✝ : SigmaFinite (μ.trim hm)
C : ℝ≥0∞
f : Set α → ℝ≥0∞
hf : ∀ (s : Set α), MeasurableSet s → μ s ≠ ⊤ → f s ≤ C
h_F_lim : ∀ (S : ℕ → Set α), (∀ (n : ℕ), MeasurableSet (S n)) → Monotone S → f (⋃ n, S n) ≤ ⨆ n, f (S n)
S : ℕ → Set α := spanningSets (μ.trim hm)
⊢ f univ ≤ C

Tactic:
have hS_mono : Monotone S := @monotone_spanningSets _ m (μ.trim hm) _

Result:
α : Type u_1
m m0 : MeasurableSpace α
μ : Measure α
hm : m ≤ m0
inst✝ : SigmaFinite (μ.trim hm)
C : ℝ≥0∞
f : Set α → ℝ≥0∞
hf : ∀ (s : Set α), MeasurableSet s → μ s ≠ ⊤ → f s ≤ C
h_F_lim : ∀ (S : ℕ → Set α), (∀ (n : ℕ), MeasurableSet (S n)) → Monotone S → f (⋃ n, S n) ≤ ⨆ n, f (S n)
S : ℕ → Set α := spanningSets (μ.trim hm)
hS_mono : Monotone S
⊢ f univ ≤ C

Proof state:
α : Type u_1
m m0 : MeasurableSpace α
μ : Measure α
hm : m ≤ m0
inst✝ : SigmaFinite (μ.trim hm)
C : ℝ≥0∞
f : Set α → ℝ≥0∞
hf : ∀ (s : Set α), MeasurableSet s → μ s ≠ ⊤ → f s ≤ C
h_F_lim : ∀ (S : ℕ → Set α), (∀ (n : ℕ), MeasurableSet (S n)) → Monotone S → f (⋃ n, S n) ≤ ⨆ n, f (S n)
S : ℕ → Set α := spanningSets (μ.trim hm)
hS_mono : Monotone S
hS_meas : ∀ (n : ℕ), MeasurableSet (S n)
n : ℕ
⊢ μ (S n) ≠ ⊤

Tactic:
exact ((le_trim hm).trans_lt (@measure_spanningSets_lt_top _ m (μ.trim hm) _ n)).ne

Result:
no goals

Proof state:
α : Type u_1
m m0 : MeasurableSpace α
μ : Measure α
hm : m ≤ m0
inst✝ : SigmaFinite (μ.trim hm)
C : ℝ≥0∞
f : Set α → ℝ≥0∞
hf : ∀ (s : Set α), MeasurableSet s → μ s ≠ ⊤ → f s ≤ C
h_F_lim : ∀ (S : ℕ → Set α), (∀ (n : ℕ), MeasurableSet (S n)) → Monotone S → f (⋃ n, S n) ≤ ⨆ n, f (S n)
S : ℕ → Set α := spanningSets (μ.trim hm)
hS_mono : Monotone S
hS_meas : ∀ (n : ℕ), MeasurableSet (S n)
⊢ f (⋃ i, spanningSets (μ.trim hm) i) ≤ C

Tactic:
refine (h_F_lim S hS_meas hS_mono).trans ?_

Result:
α : Type u_1
m m0 : MeasurableSpace α
μ : Measure α
hm : m ≤ m0
inst✝ : SigmaFinite (μ.trim hm)
C : ℝ≥0∞
f : Set α → ℝ≥0∞
hf : ∀ (s : Set α), MeasurableSet s → μ s ≠ ⊤ → f s ≤ C
h_F_lim : ∀ (S : ℕ → Set α), (∀ (n : ℕ), MeasurableSet (S n)) → Monotone S → f (⋃ n, S n) ≤ ⨆ n, f (S n)
S : ℕ → Set α := spanningSets (μ.trim hm)
hS_mono : Monotone S
hS_meas : ∀ (n : ℕ), MeasurableSet (S n)
⊢ ⨆ n, f (S n) ≤ C