-- Mathlib/Analysis/Convolution.lean
theorem _root_.BddAbove.convolutionExistsAt [MeasurableAdd₂ G] [SFinite μ] {x₀ : G} {s : Set G}
    (hbg : BddAbove ((fun i => ‖g i‖) '' ((fun t => x₀ - t) ⁻¹' s))) (hs : MeasurableSet s)
    (h2s : (support fun t => L (f t) (g (x₀ - t))) ⊆ s) (hf : IntegrableOn f s μ)
    (hmg : AEStronglyMeasurable g μ) : ConvolutionExistsAt f g x₀ L μ

Proof state:
𝕜 : Type u𝕜
G : Type uG
E : Type uE
E' : Type uE'
F : Type uF
inst✝¹² : NormedAddCommGroup E
inst✝¹¹ : NormedAddCommGroup E'
inst✝¹⁰ : NormedAddCommGroup F
f : G → E
g : G → E'
inst✝⁹ : NontriviallyNormedField 𝕜
inst✝⁸ : NormedSpace 𝕜 E
inst✝⁷ : NormedSpace 𝕜 E'
inst✝⁶ : NormedSpace 𝕜 F
L : E →L[𝕜] E' →L[𝕜] F
inst✝⁵ : MeasurableSpace G
μ : Measure G
inst✝⁴ : AddCommGroup G
inst✝³ : MeasurableNeg G
inst✝² : μ.IsAddLeftInvariant
inst✝¹ : MeasurableAdd₂ G
inst✝ : SFinite μ
x₀ : G
s : Set G
hbg : BddAbove ((fun i => ‖g i‖) '' ((fun t => x₀ - t) ⁻¹' s))
hs : MeasurableSet s
h2s : (support fun t => (L (f t)) (g (x₀ - t))) ⊆ s
hf : IntegrableOn f s μ
hmg : AEStronglyMeasurable g μ
⊢ ConvolutionExistsAt f g x₀ L μ

Tactic:
refine BddAbove.convolutionExistsAt' L ?_ hs h2s hf ?_

Result:
case refine_1
𝕜 : Type u𝕜
G : Type uG
E : Type uE
E' : Type uE'
F : Type uF
inst✝¹² : NormedAddCommGroup E
inst✝¹¹ : NormedAddCommGroup E'
inst✝¹⁰ : NormedAddCommGroup F
f : G → E
g : G → E'
inst✝⁹ : NontriviallyNormedField 𝕜
inst✝⁸ : NormedSpace 𝕜 E
inst✝⁷ : NormedSpace 𝕜 E'
inst✝⁶ : NormedSpace 𝕜 F
L : E →L[𝕜] E' →L[𝕜] F
inst✝⁵ : MeasurableSpace G
μ : Measure G
inst✝⁴ : AddCommGroup G
inst✝³ : MeasurableNeg G
inst✝² : μ.IsAddLeftInvariant
inst✝¹ : MeasurableAdd₂ G
inst✝ : SFinite μ
x₀ : G
s : Set G
hbg : BddAbove ((fun i => ‖g i‖) '' ((fun t => x₀ - t) ⁻¹' s))
hs : MeasurableSet s
h2s : (support fun t => (L (f t)) (g (x₀ - t))) ⊆ s
hf : IntegrableOn f s μ
hmg : AEStronglyMeasurable g μ
⊢ BddAbove ((fun i => ‖g i‖) '' ((fun t => -t + x₀) ⁻¹' s))

case refine_2
𝕜 : Type u𝕜
G : Type uG
E : Type uE
E' : Type uE'
F : Type uF
inst✝¹² : NormedAddCommGroup E
inst✝¹¹ : NormedAddCommGroup E'
inst✝¹⁰ : NormedAddCommGroup F
f : G → E
g : G → E'
inst✝⁹ : NontriviallyNormedField 𝕜
inst✝⁸ : NormedSpace 𝕜 E
inst✝⁷ : NormedSpace 𝕜 E'
inst✝⁶ : NormedSpace 𝕜 F
L : E →L[𝕜] E' →L[𝕜] F
inst✝⁵ : MeasurableSpace G
μ : Measure G
inst✝⁴ : AddCommGroup G
inst✝³ : MeasurableNeg G
inst✝² : μ.IsAddLeftInvariant
inst✝¹ : MeasurableAdd₂ G
inst✝ : SFinite μ
x₀ : G
s : Set G
hbg : BddAbove ((fun i => ‖g i‖) '' ((fun t => x₀ - t) ⁻¹' s))
hs : MeasurableSet s
h2s : (support fun t => (L (f t)) (g (x₀ - t))) ⊆ s
hf : IntegrableOn f s μ
hmg : AEStronglyMeasurable g μ
⊢ AEStronglyMeasurable g (Measure.map (fun t => x₀ - t) (μ.restrict s))

Proof state:
case refine_2
𝕜 : Type u𝕜
G : Type uG
E : Type uE
E' : Type uE'
F : Type uF
inst✝¹² : NormedAddCommGroup E
inst✝¹¹ : NormedAddCommGroup E'
inst✝¹⁰ : NormedAddCommGroup F
f : G → E
g : G → E'
inst✝⁹ : NontriviallyNormedField 𝕜
inst✝⁸ : NormedSpace 𝕜 E
inst✝⁷ : NormedSpace 𝕜 E'
inst✝⁶ : NormedSpace 𝕜 F
L : E →L[𝕜] E' →L[𝕜] F
inst✝⁵ : MeasurableSpace G
μ : Measure G
inst✝⁴ : AddCommGroup G
inst✝³ : MeasurableNeg G
inst✝² : μ.IsAddLeftInvariant
inst✝¹ : MeasurableAdd₂ G
inst✝ : SFinite μ
x₀ : G
s : Set G
hbg : BddAbove ((fun i => ‖g i‖) '' ((fun t => x₀ - t) ⁻¹' s))
hs : MeasurableSet s
h2s : (support fun t => (L (f t)) (g (x₀ - t))) ⊆ s
hf : IntegrableOn f s μ
hmg : AEStronglyMeasurable g μ
this : AEStronglyMeasurable g (Measure.map (fun t => x₀ - t) μ)
⊢ AEStronglyMeasurable g (Measure.map (fun t => x₀ - t) (μ.restrict s))

Tactic:
apply this.mono_measure

Result:
case refine_2
𝕜 : Type u𝕜
G : Type uG
E : Type uE
E' : Type uE'
F : Type uF
inst✝¹² : NormedAddCommGroup E
inst✝¹¹ : NormedAddCommGroup E'
inst✝¹⁰ : NormedAddCommGroup F
f : G → E
g : G → E'
inst✝⁹ : NontriviallyNormedField 𝕜
inst✝⁸ : NormedSpace 𝕜 E
inst✝⁷ : NormedSpace 𝕜 E'
inst✝⁶ : NormedSpace 𝕜 F
L : E →L[𝕜] E' →L[𝕜] F
inst✝⁵ : MeasurableSpace G
μ : Measure G
inst✝⁴ : AddCommGroup G
inst✝³ : MeasurableNeg G
inst✝² : μ.IsAddLeftInvariant
inst✝¹ : MeasurableAdd₂ G
inst✝ : SFinite μ
x₀ : G
s : Set G
hbg : BddAbove ((fun i => ‖g i‖) '' ((fun t => x₀ - t) ⁻¹' s))
hs : MeasurableSet s
h2s : (support fun t => (L (f t)) (g (x₀ - t))) ⊆ s
hf : IntegrableOn f s μ
hmg : AEStronglyMeasurable g μ
this : AEStronglyMeasurable g (Measure.map (fun t => x₀ - t) μ)
⊢ Measure.map (fun t => x₀ - t) (μ.restrict s) ≤ Measure.map (fun t => x₀ - t) μ

Proof state:
case refine_1
𝕜 : Type u𝕜
G : Type uG
E : Type uE
E' : Type uE'
F : Type uF
inst✝¹² : NormedAddCommGroup E
inst✝¹¹ : NormedAddCommGroup E'
inst✝¹⁰ : NormedAddCommGroup F
f : G → E
g : G → E'
inst✝⁹ : NontriviallyNormedField 𝕜
inst✝⁸ : NormedSpace 𝕜 E
inst✝⁷ : NormedSpace 𝕜 E'
inst✝⁶ : NormedSpace 𝕜 F
L : E →L[𝕜] E' →L[𝕜] F
inst✝⁵ : MeasurableSpace G
μ : Measure G
inst✝⁴ : AddCommGroup G
inst✝³ : MeasurableNeg G
inst✝² : μ.IsAddLeftInvariant
inst✝¹ : MeasurableAdd₂ G
inst✝ : SFinite μ
x₀ : G
s : Set G
hbg : BddAbove ((fun i => ‖g i‖) '' ((fun t => x₀ - t) ⁻¹' s))
hs : MeasurableSet s
h2s : (support fun t => (L (f t)) (g (x₀ - t))) ⊆ s
hf : IntegrableOn f s μ
hmg : AEStronglyMeasurable g μ
⊢ BddAbove ((fun i => ‖g i‖) '' ((fun t => -t + x₀) ⁻¹' s))

Tactic:
simp_rw [← sub_eq_neg_add, hbg]

Result:
no goals

Proof state:
case refine_2
𝕜 : Type u𝕜
G : Type uG
E : Type uE
E' : Type uE'
F : Type uF
inst✝¹² : NormedAddCommGroup E
inst✝¹¹ : NormedAddCommGroup E'
inst✝¹⁰ : NormedAddCommGroup F
f : G → E
g : G → E'
inst✝⁹ : NontriviallyNormedField 𝕜
inst✝⁸ : NormedSpace 𝕜 E
inst✝⁷ : NormedSpace 𝕜 E'
inst✝⁶ : NormedSpace 𝕜 F
L : E →L[𝕜] E' →L[𝕜] F
inst✝⁵ : MeasurableSpace G
μ : Measure G
inst✝⁴ : AddCommGroup G
inst✝³ : MeasurableNeg G
inst✝² : μ.IsAddLeftInvariant
inst✝¹ : MeasurableAdd₂ G
inst✝ : SFinite μ
x₀ : G
s : Set G
hbg : BddAbove ((fun i => ‖g i‖) '' ((fun t => x₀ - t) ⁻¹' s))
hs : MeasurableSet s
h2s : (support fun t => (L (f t)) (g (x₀ - t))) ⊆ s
hf : IntegrableOn f s μ
hmg : AEStronglyMeasurable g μ
this : AEStronglyMeasurable g (Measure.map (fun t => x₀ - t) μ)
⊢ Measure.map (fun t => x₀ - t) (μ.restrict s) ≤ Measure.map (fun t => x₀ - t) μ

Tactic:
exact map_mono restrict_le_self (measurable_const.sub measurable_id')

Result:
no goals