Theorem: MeasureTheory.lintegral_mono_ae
File: Mathlib/MeasureTheory/Integral/Lebesgue.lean

Proof steps:
state_before: α : Type u_1
β : Type u_2
γ : Type u_3
δ : Type u_4
m : MeasurableSpace α
μ ν : Measure α
f g : α → ℝ≥0∞
h : ∀ᵐ (a : α) ∂μ, f a ≤ g a
⊢ ∫⁻ (a : α), f a ∂μ ≤ ∫⁻ (a : α), g a ∂μ
state_after: case intro.intro.intro
α : Type u_1
β : Type u_2
γ : Type u_3
δ : Type u_4
m : MeasurableSpace α
μ ν : Measure α
f g : α → ℝ≥0∞
h : ∀ᵐ (a : α) ∂μ, f a ≤ g a
t : Set α
hts : {x | (fun a => f a ≤ g a) x}ᶜ ⊆ t
ht : MeasurableSet t
ht0 : μ t = 0
⊢ ∫⁻ (a : α), f a ∂μ ≤ ∫⁻ (a : α), g a ∂μ
tactic: rcases exists_measurable_superset_of_null h with ⟨t, hts, ht, ht0⟩
state_before: case intro.intro.intro
α : Type u_1
β : Type u_2
γ : Type u_3
δ : Type u_4
m : MeasurableSpace α
μ ν : Measure α
f g : α → ℝ≥0∞
h : ∀ᵐ (a : α) ∂μ, f a ≤ g a
t : Set α
hts : {x | (fun a => f a ≤ g a) x}ᶜ ⊆ t
ht : MeasurableSet t
ht0 : μ t = 0
⊢ ∫⁻ (a : α), f a ∂μ ≤ ∫⁻ (a : α), g a ∂μ
state_after: case intro.intro.intro
α : Type u_1
β : Type u_2
γ : Type u_3
δ : Type u_4
m : MeasurableSpace α
μ ν : Measure α
f g : α → ℝ≥0∞
h : ∀ᵐ (a : α) ∂μ, f a ≤ g a
t : Set α
hts : {x | (fun a => f a ≤ g a) x}ᶜ ⊆ t
ht : MeasurableSet t
ht0 : μ t = 0
this : ∀ᵐ (x : α) ∂μ, x ∉ t
⊢ ∫⁻ (a : α), f a ∂μ ≤ ∫⁻ (a : α), g a ∂μ
tactic: have : ∀ᵐ x ∂μ, x ∉ t := measure_zero_iff_ae_nmem.1 ht0
state_before: case intro.intro.intro
α : Type u_1
β : Type u_2
γ : Type u_3
δ : Type u_4
m : MeasurableSpace α
μ ν : Measure α
f g : α → ℝ≥0∞
h : ∀ᵐ (a : α) ∂μ, f a ≤ g a
t : Set α
hts : {x | (fun a => f a ≤ g a) x}ᶜ ⊆ t
ht : MeasurableSet t
ht0 : μ t = 0
this : ∀ᵐ (x : α) ∂μ, x ∉ t
⊢ ∫⁻ (a : α), f a ∂μ ≤ ∫⁻ (a : α), g a ∂μ
state_after: case intro.intro.intro
α : Type u_1
β : Type u_2
γ : Type u_3
δ : Type u_4
m : MeasurableSpace α
μ ν : Measure α
f g : α → ℝ≥0∞
h : ∀ᵐ (a : α) ∂μ, f a ≤ g a
t : Set α
hts : {x | (fun a => f a ≤ g a) x}ᶜ ⊆ t
ht : MeasurableSet t
ht0 : μ t = 0
this : ∀ᵐ (x : α) ∂μ, x ∉ t
⊢ ⨆ g, ⨆ (_ : ↑g ≤ fun a => f a), g.lintegral μ ≤ ⨆ g_1, ⨆ (_ : ↑g_1 ≤ fun a => g a), g_1.lintegral μ
tactic: rw [lintegral, lintegral]
state_before: case intro.intro.intro
α : Type u_1
β : Type u_2
γ : Type u_3
δ : Type u_4
m : MeasurableSpace α
μ ν : Measure α
f g : α → ℝ≥0∞
h : ∀ᵐ (a : α) ∂μ, f a ≤ g a
t : Set α
hts : {x | (fun a => f a ≤ g a) x}ᶜ ⊆ t
ht : MeasurableSet t
ht0 : μ t = 0
this : ∀ᵐ (x : α) ∂μ, x ∉ t
⊢ ⨆ g, ⨆ (_ : ↑g ≤ fun a => f a), g.lintegral μ ≤ ⨆ g_1, ⨆ (_ : ↑g_1 ≤ fun a => g a), g_1.lintegral μ
state_after: case intro.intro.intro.refine_1
α : Type u_1
β : Type u_2
γ : Type u_3
δ : Type u_4
m : MeasurableSpace α
μ ν : Measure α
f g : α → ℝ≥0∞
h : ∀ᵐ (a : α) ∂μ, f a ≤ g a
t : Set α
hts : {x | (fun a => f a ≤ g a) x}ᶜ ⊆ t
ht : MeasurableSet t
ht0 : μ t = 0
this : ∀ᵐ (x : α) ∂μ, x ∉ t
s : α →ₛ ℝ≥0∞
hfs : ↑s ≤ fun a => f a
⊢ ↑(s.restrict tᶜ) ≤ fun a => g a

case intro.intro.intro.refine_2
α : Type u_1
β : Type u_2
γ : Type u_3
δ : Type u_4
m : MeasurableSpace α
μ ν : Measure α
f g : α → ℝ≥0∞
h : ∀ᵐ (a : α) ∂μ, f a ≤ g a
t : Set α
hts : {x | (fun a => f a ≤ g a) x}ᶜ ⊆ t
ht : MeasurableSet t
ht0 : μ t = 0
this : ∀ᵐ (x : α) ∂μ, x ∉ t
s : α →ₛ ℝ≥0∞
hfs : ↑s ≤ fun a => f a
⊢ s.lintegral μ ≤ (s.restrict tᶜ).lintegral μ
tactic: refine iSup_le fun s => iSup_le fun hfs => le_iSup_of_le (s.restrict tᶜ) <| le_iSup_of_le ?_ ?_