Theorem: MeasureTheory.integral_norm_eq_pos_sub_neg
File: Mathlib/MeasureTheory/Integral/SetIntegral.lean

Proof steps:
state_before: X : Type u_1
Y : Type u_2
E : Type u_3
F : Type u_4
inst✝² : MeasurableSpace X
inst✝¹ : NormedAddCommGroup E
inst✝ : NormedSpace ℝ E
f✝ g : X → E
s t : Set X
μ ν : Measure X
l l' : Filter X
f : X → ℝ
hfi : Integrable f μ
h_meas : NullMeasurableSet {x | 0 ≤ f x} μ
⊢ ∫ (x : X), ‖f x‖ ∂μ = ∫ (x : X) in {x | 0 ≤ f x}, ‖f x‖ ∂μ + ∫ (x : X) in {x | 0 ≤ f x}ᶜ, ‖f x‖ ∂μ
state_after: no goals
tactic: rw [← integral_add_compl₀ h_meas hfi.norm]
state_before: X : Type u_1
Y : Type u_2
E : Type u_3
F : Type u_4
inst✝² : MeasurableSpace X
inst✝¹ : NormedAddCommGroup E
inst✝ : NormedSpace ℝ E
f✝ g : X → E
s t : Set X
μ ν : Measure X
l l' : Filter X
f : X → ℝ
hfi : Integrable f μ
h_meas : NullMeasurableSet {x | 0 ≤ f x} μ
⊢ ∫ (x : X) in {x | 0 ≤ f x}, ‖f x‖ ∂μ + ∫ (x : X) in {x | 0 ≤ f x}ᶜ, ‖f x‖ ∂μ =
    ∫ (x : X) in {x | 0 ≤ f x}, f x ∂μ + ∫ (x : X) in {x | 0 ≤ f x}ᶜ, ‖f x‖ ∂μ
state_after: case e_a
X : Type u_1
Y : Type u_2
E : Type u_3
F : Type u_4
inst✝² : MeasurableSpace X
inst✝¹ : NormedAddCommGroup E
inst✝ : NormedSpace ℝ E
f✝ g : X → E
s t : Set X
μ ν : Measure X
l l' : Filter X
f : X → ℝ
hfi : Integrable f μ
h_meas : NullMeasurableSet {x | 0 ≤ f x} μ
⊢ ∫ (x : X) in {x | 0 ≤ f x}, ‖f x‖ ∂μ = ∫ (x : X) in {x | 0 ≤ f x}, f x ∂μ
tactic: congr 1
state_before: case e_a
X : Type u_1
Y : Type u_2
E : Type u_3
F : Type u_4
inst✝² : MeasurableSpace X
inst✝¹ : NormedAddCommGroup E
inst✝ : NormedSpace ℝ E
f✝ g : X → E
s t : Set X
μ ν : Measure X
l l' : Filter X
f : X → ℝ
hfi : Integrable f μ
h_meas : NullMeasurableSet {x | 0 ≤ f x} μ
⊢ ∫ (x : X) in {x | 0 ≤ f x}, ‖f x‖ ∂μ = ∫ (x : X) in {x | 0 ≤ f x}, f x ∂μ
state_after: case e_a
X : Type u_1
Y : Type u_2
E : Type u_3
F : Type u_4
inst✝² : MeasurableSpace X
inst✝¹ : NormedAddCommGroup E
inst✝ : NormedSpace ℝ E
f✝ g : X → E
s t : Set X
μ ν : Measure X
l l' : Filter X
f : X → ℝ
hfi : Integrable f μ
h_meas : NullMeasurableSet {x | 0 ≤ f x} μ
x : X
hx : x ∈ {x | 0 ≤ f x}
⊢ ‖f x‖ = f x
tactic: refine setIntegral_congr₀ h_meas fun x hx => ?_
state_before: case e_a
X : Type u_1
Y : Type u_2
E : Type u_3
F : Type u_4
inst✝² : MeasurableSpace X
inst✝¹ : NormedAddCommGroup E
inst✝ : NormedSpace ℝ E
f✝ g : X → E
s t : Set X
μ ν : Measure X
l l' : Filter X
f : X → ℝ
hfi : Integrable f μ
h_meas : NullMeasurableSet {x | 0 ≤ f x} μ
x : X
hx : x ∈ {x | 0 ≤ f x}
⊢ ‖f x‖ = f x
state_after: X : Type u_1
Y : Type u_2
E : Type u_3
F : Type u_4
inst✝² : MeasurableSpace X
inst✝¹ : NormedAddCommGroup E
inst✝ : NormedSpace ℝ E
f✝ g : X → E
s t : Set X
μ ν : Measure X
l l' : Filter X
f : X → ℝ
hfi : Integrable f μ
h_meas : NullMeasurableSet {x | 0 ≤ f x} μ
x : X
hx : x ∈ {x | 0 ≤ f x}
⊢ 0 ≤ f x
tactic: rw [Real.norm_eq_abs, abs_eq_self.mpr _]
state_before: X : Type u_1
Y : Type u_2
E : Type u_3
F : Type u_4
inst✝² : MeasurableSpace X
inst✝¹ : NormedAddCommGroup E
inst✝ : NormedSpace ℝ E
f✝ g : X → E
s t : Set X
μ ν : Measure X
l l' : Filter X
f : X → ℝ
hfi : Integrable f μ
h_meas : NullMeasurableSet {x | 0 ≤ f x} μ
x : X
hx : x ∈ {x | 0 ≤ f x}
⊢ 0 ≤ f x
state_after: no goals
tactic: exact hx
state_before: X : Type u_1
Y : Type u_2
E : Type u_3
F : Type u_4
inst✝² : MeasurableSpace X
inst✝¹ : NormedAddCommGroup E
inst✝ : NormedSpace ℝ E
f✝ g : X → E
s t : Set X
μ ν : Measure X
l l' : Filter X
f : X → ℝ
hfi : Integrable f μ
h_meas : NullMeasurableSet {x | 0 ≤ f x} μ
⊢ ∫ (x : X) in {x | 0 ≤ f x}, f x ∂μ + ∫ (x : X) in {x | 0 ≤ f x}ᶜ, ‖f x‖ ∂μ =
    ∫ (x : X) in {x | 0 ≤ f x}, f x ∂μ - ∫ (x : X) in {x | 0 ≤ f x}ᶜ, f x ∂μ
state_after: case e_a
X : Type u_1
Y : Type u_2
E : Type u_3
F : Type u_4
inst✝² : MeasurableSpace X
inst✝¹ : NormedAddCommGroup E
inst✝ : NormedSpace ℝ E
f✝ g : X → E
s t : Set X
μ ν : Measure X
l l' : Filter X
f : X → ℝ
hfi : Integrable f μ
h_meas : NullMeasurableSet {x | 0 ≤ f x} μ
⊢ ∫ (x : X) in {x | 0 ≤ f x}ᶜ, ‖f x‖ ∂μ = -∫ (x : X) in {x | 0 ≤ f x}ᶜ, f x ∂μ
tactic: congr 1
state_before: case e_a
X : Type u_1
Y : Type u_2
E : Type u_3
F : Type u_4
inst✝² : MeasurableSpace X
inst✝¹ : NormedAddCommGroup E
inst✝ : NormedSpace ℝ E
f✝ g : X → E
s t : Set X
μ ν : Measure X
l l' : Filter X
f : X → ℝ
hfi : Integrable f μ
h_meas : NullMeasurableSet {x | 0 ≤ f x} μ
⊢ ∫ (x : X) in {x | 0 ≤ f x}ᶜ, ‖f x‖ ∂μ = -∫ (x : X) in {x | 0 ≤ f x}ᶜ, f x ∂μ
state_after: case e_a
X : Type u_1
Y : Type u_2
E : Type u_3
F : Type u_4
inst✝² : MeasurableSpace X
inst✝¹ : NormedAddCommGroup E
inst✝ : NormedSpace ℝ E
f✝ g : X → E
s t : Set X
μ ν : Measure X
l l' : Filter X
f : X → ℝ
hfi : Integrable f μ
h_meas : NullMeasurableSet {x | 0 ≤ f x} μ
⊢ ∫ (x : X) in {x | 0 ≤ f x}ᶜ, ‖f x‖ ∂μ = ∫ (a : X) in {x | 0 ≤ f x}ᶜ, -f a ∂μ
tactic: rw [← integral_neg]
state_before: case e_a
X : Type u_1
Y : Type u_2
E : Type u_3
F : Type u_4
inst✝² : MeasurableSpace X
inst✝¹ : NormedAddCommGroup E
inst✝ : NormedSpace ℝ E
f✝ g : X → E
s t : Set X
μ ν : Measure X
l l' : Filter X
f : X → ℝ
hfi : Integrable f μ
h_meas : NullMeasurableSet {x | 0 ≤ f x} μ
⊢ ∫ (x : X) in {x | 0 ≤ f x}ᶜ, ‖f x‖ ∂μ = ∫ (a : X) in {x | 0 ≤ f x}ᶜ, -f a ∂μ
state_after: case e_a
X : Type u_1
Y : Type u_2
E : Type u_3
F : Type u_4
inst✝² : MeasurableSpace X
inst✝¹ : NormedAddCommGroup E
inst✝ : NormedSpace ℝ E
f✝ g : X → E
s t : Set X
μ ν : Measure X
l l' : Filter X
f : X → ℝ
hfi : Integrable f μ
h_meas : NullMeasurableSet {x | 0 ≤ f x} μ
x : X
hx : x ∈ {x | 0 ≤ f x}ᶜ
⊢ ‖f x‖ = -f x
tactic: refine setIntegral_congr₀ h_meas.compl fun x hx => ?_
state_before: case e_a
X : Type u_1
Y : Type u_2
E : Type u_3
F : Type u_4
inst✝² : MeasurableSpace X
inst✝¹ : NormedAddCommGroup E
inst✝ : NormedSpace ℝ E
f✝ g : X → E
s t : Set X
μ ν : Measure X
l l' : Filter X
f : X → ℝ
hfi : Integrable f μ
h_meas : NullMeasurableSet {x | 0 ≤ f x} μ
x : X
hx : x ∈ {x | 0 ≤ f x}ᶜ
⊢ ‖f x‖ = -f x
state_after: X : Type u_1
Y : Type u_2
E : Type u_3
F : Type u_4
inst✝² : MeasurableSpace X
inst✝¹ : NormedAddCommGroup E
inst✝ : NormedSpace ℝ E
f✝ g : X → E
s t : Set X
μ ν : Measure X
l l' : Filter X
f : X → ℝ
hfi : Integrable f μ
h_meas : NullMeasurableSet {x | 0 ≤ f x} μ
x : X
hx : x ∈ {x | 0 ≤ f x}ᶜ
⊢ f x ≤ 0
tactic: rw [Real.norm_eq_abs, abs_eq_neg_self.mpr _]
state_before: X : Type u_1
Y : Type u_2
E : Type u_3
F : Type u_4
inst✝² : MeasurableSpace X
inst✝¹ : NormedAddCommGroup E
inst✝ : NormedSpace ℝ E
f✝ g : X → E
s t : Set X
μ ν : Measure X
l l' : Filter X
f : X → ℝ
hfi : Integrable f μ
h_meas : NullMeasurableSet {x | 0 ≤ f x} μ
x : X
hx : x ∈ {x | 0 ≤ f x}ᶜ
⊢ f x ≤ 0
state_after: X : Type u_1
Y : Type u_2
E : Type u_3
F : Type u_4
inst✝² : MeasurableSpace X
inst✝¹ : NormedAddCommGroup E
inst✝ : NormedSpace ℝ E
f✝ g : X → E
s t : Set X
μ ν : Measure X
l l' : Filter X
f : X → ℝ
hfi : Integrable f μ
h_meas : NullMeasurableSet {x | 0 ≤ f x} μ
x : X
hx : ¬0 ≤ f x
⊢ f x ≤ 0
tactic: rw [Set.mem_compl_iff, Set.nmem_setOf_iff] at hx
state_before: X : Type u_1
Y : Type u_2
E : Type u_3
F : Type u_4
inst✝² : MeasurableSpace X
inst✝¹ : NormedAddCommGroup E
inst✝ : NormedSpace ℝ E
f✝ g : X → E
s t : Set X
μ ν : Measure X
l l' : Filter X
f : X → ℝ
hfi : Integrable f μ
h_meas : NullMeasurableSet {x | 0 ≤ f x} μ
x : X
hx : ¬0 ≤ f x
⊢ f x ≤ 0
state_after: no goals
tactic: linarith
state_before: X : Type u_1
Y : Type u_2
E : Type u_3
F : Type u_4
inst✝² : MeasurableSpace X
inst✝¹ : NormedAddCommGroup E
inst✝ : NormedSpace ℝ E
f✝ g : X → E
s t : Set X
μ ν : Measure X
l l' : Filter X
f : X → ℝ
hfi : Integrable f μ
h_meas : NullMeasurableSet {x | 0 ≤ f x} μ
⊢ ∫ (x : X) in {x | 0 ≤ f x}, f x ∂μ - ∫ (x : X) in {x | 0 ≤ f x}ᶜ, f x ∂μ =
    ∫ (x : X) in {x | 0 ≤ f x}, f x ∂μ - ∫ (x : X) in {x | f x ≤ 0}, f x ∂μ
state_after: X : Type u_1
Y : Type u_2
E : Type u_3
F : Type u_4
inst✝² : MeasurableSpace X
inst✝¹ : NormedAddCommGroup E
inst✝ : NormedSpace ℝ E
f✝ g : X → E
s t : Set X
μ ν : Measure X
l l' : Filter X
f : X → ℝ
hfi : Integrable f μ
h_meas : NullMeasurableSet {x | 0 ≤ f x} μ
⊢ ∫ (x : X) in {x | 0 ≤ f x}, f x ∂μ - ∫ (x : X) in {a | ¬0 ≤ f a}, f x ∂μ =
    ∫ (x : X) in {x | 0 ≤ f x}, f x ∂μ - ∫ (x : X) in {x | f x < 0}, f x ∂μ
tactic: rw [← setIntegral_neg_eq_setIntegral_nonpos hfi.1, compl_setOf]
state_before: X : Type u_1
Y : Type u_2
E : Type u_3
F : Type u_4
inst✝² : MeasurableSpace X
inst✝¹ : NormedAddCommGroup E
inst✝ : NormedSpace ℝ E
f✝ g : X → E
s t : Set X
μ ν : Measure X
l l' : Filter X
f : X → ℝ
hfi : Integrable f μ
h_meas : NullMeasurableSet {x | 0 ≤ f x} μ
⊢ ∫ (x : X) in {x | 0 ≤ f x}, f x ∂μ - ∫ (x : X) in {a | ¬0 ≤ f a}, f x ∂μ =
    ∫ (x : X) in {x | 0 ≤ f x}, f x ∂μ - ∫ (x : X) in {x | f x < 0}, f x ∂μ
state_after: no goals
tactic: simp only [not_le]