Theorem: MeasureTheory.Measure.integral_isMulLeftInvariant_eq_smul_of_hasCompactSupport
File: Mathlib/MeasureTheory/Measure/Haar/Unique.lean

tactic: rcases h'f.eq_zero_or_locallyCompactSpace_of_group hf with Hf|Hf
state_before: G : Type u_1
inst✝⁷ : TopologicalSpace G
inst✝⁶ : Group G
inst✝⁵ : TopologicalGroup G
inst✝⁴ : MeasurableSpace G
inst✝³ : BorelSpace G
μ' μ : Measure G
inst✝² : μ.IsHaarMeasure
inst✝¹ : IsFiniteMeasureOnCompacts μ'
inst✝ : μ'.IsMulLeftInvariant
f : G → ℝ
hf : Continuous f
h'f : HasCompactSupport f
⊢ ∫ (x : G), f x ∂μ' = ∫ (x : G), f x ∂μ'.haarScalarFactor μ • μ
state_after: case inl
G : Type u_1
inst✝⁷ : TopologicalSpace G
inst✝⁶ : Group G
inst✝⁵ : TopologicalGroup G
inst✝⁴ : MeasurableSpace G
inst✝³ : BorelSpace G
μ' μ : Measure G
inst✝² : μ.IsHaarMeasure
inst✝¹ : IsFiniteMeasureOnCompacts μ'
inst✝ : μ'.IsMulLeftInvariant
f : G → ℝ
hf : Continuous f
h'f : HasCompactSupport f
Hf : f = 0
⊢ ∫ (x : G), f x ∂μ' = ∫ (x : G), f x ∂μ'.haarScalarFactor μ • μ

case inr
G : Type u_1
inst✝⁷ : TopologicalSpace G
inst✝⁶ : Group G
inst✝⁵ : TopologicalGroup G
inst✝⁴ : MeasurableSpace G
inst✝³ : BorelSpace G
μ' μ : Measure G
inst✝² : μ.IsHaarMeasure
inst✝¹ : IsFiniteMeasureOnCompacts μ'
inst✝ : μ'.IsMulLeftInvariant
f : G → ℝ
hf : Continuous f
h'f : HasCompactSupport f
Hf : LocallyCompactSpace G
⊢ ∫ (x : G), f x ∂μ' = ∫ (x : G), f x ∂μ'.haarScalarFactor μ • μ

tactic: simp [Hf]
state_before: case inl
G : Type u_1
inst✝⁷ : TopologicalSpace G
inst✝⁶ : Group G
inst✝⁵ : TopologicalGroup G
inst✝⁴ : MeasurableSpace G
inst✝³ : BorelSpace G
μ' μ : Measure G
inst✝² : μ.IsHaarMeasure
inst✝¹ : IsFiniteMeasureOnCompacts μ'
inst✝ : μ'.IsMulLeftInvariant
f : G → ℝ
hf : Continuous f
h'f : HasCompactSupport f
Hf : f = 0
⊢ ∫ (x : G), f x ∂μ' = ∫ (x : G), f x ∂μ'.haarScalarFactor μ • μ
state_after: no goals

tactic: simp only [haarScalarFactor, Hf, not_true_eq_false, ite_false]
state_before: case inr
G : Type u_1
inst✝⁷ : TopologicalSpace G
inst✝⁶ : Group G
inst✝⁵ : TopologicalGroup G
inst✝⁴ : MeasurableSpace G
inst✝³ : BorelSpace G
μ' μ : Measure G
inst✝² : μ.IsHaarMeasure
inst✝¹ : IsFiniteMeasureOnCompacts μ'
inst✝ : μ'.IsMulLeftInvariant
f : G → ℝ
hf : Continuous f
h'f : HasCompactSupport f
Hf : LocallyCompactSpace G
⊢ ∫ (x : G), f x ∂μ' = ∫ (x : G), f x ∂μ'.haarScalarFactor μ • μ
state_after: case inr
G : Type u_1
inst✝⁷ : TopologicalSpace G
inst✝⁶ : Group G
inst✝⁵ : TopologicalGroup G
inst✝⁴ : MeasurableSpace G
inst✝³ : BorelSpace G
μ' μ : Measure G
inst✝² : μ.IsHaarMeasure
inst✝¹ : IsFiniteMeasureOnCompacts μ'
inst✝ : μ'.IsMulLeftInvariant
f : G → ℝ
hf : Continuous f
h'f : HasCompactSupport f
Hf : LocallyCompactSpace G
⊢ ∫ (x : G), f x ∂μ' = ∫ (x : G), f x ∂⋯.choose • μ

tactic: exact (exists_integral_isMulLeftInvariant_eq_smul_of_hasCompactSupport μ' μ).choose_spec
  f hf h'f
state_before: case inr
G : Type u_1
inst✝⁷ : TopologicalSpace G
inst✝⁶ : Group G
inst✝⁵ : TopologicalGroup G
inst✝⁴ : MeasurableSpace G
inst✝³ : BorelSpace G
μ' μ : Measure G
inst✝² : μ.IsHaarMeasure
inst✝¹ : IsFiniteMeasureOnCompacts μ'
inst✝ : μ'.IsMulLeftInvariant
f : G → ℝ
hf : Continuous f
h'f : HasCompactSupport f
Hf : LocallyCompactSpace G
⊢ ∫ (x : G), f x ∂μ' = ∫ (x : G), f x ∂⋯.choose • μ
state_after: no goals