-- Mathlib/Analysis/Calculus/Rademacher.lean
theorem integral_inv_smul_sub_mul_tendsto_integral_lineDeriv_mul
    (hf : LipschitzWith C f) (hg : Integrable g μ) (v : E) :
    Tendsto (fun (t : ℝ) ↦ ∫ x, (t⁻¹ • (f (x + t • v) - f x)) * g x ∂μ) (𝓝[>] 0)
      (𝓝 (∫ x, lineDeriv ℝ f x v * g x ∂μ))

Proof state:
case h_lim
E : Type u_1
inst✝⁵ : NormedAddCommGroup E
inst✝⁴ : NormedSpace ℝ E
inst✝³ : MeasurableSpace E
inst✝² : BorelSpace E
C : ℝ≥0
f g : E → ℝ
μ : Measure E
inst✝¹ : FiniteDimensional ℝ E
inst✝ : μ.IsAddHaarMeasure
hf : LipschitzWith C f
hg : Integrable g μ
v : E
⊢ ∀ᵐ (a : E) ∂μ, Tendsto (fun n => n⁻¹ • (f (a + n • v) - f a) * g a) (𝓝[>] 0) (𝓝 (lineDeriv ℝ f a v * g a))

Tactic:
filter_upwards [hf.ae_lineDifferentiableAt v] with x hx

Result:
case h
E : Type u_1
inst✝⁵ : NormedAddCommGroup E
inst✝⁴ : NormedSpace ℝ E
inst✝³ : MeasurableSpace E
inst✝² : BorelSpace E
C : ℝ≥0
f g : E → ℝ
μ : Measure E
inst✝¹ : FiniteDimensional ℝ E
inst✝ : μ.IsAddHaarMeasure
hf : LipschitzWith C f
hg : Integrable g μ
v x : E
hx : LineDifferentiableAt ℝ f x v
⊢ Tendsto (fun n => n⁻¹ • (f (x + n • v) - f x) * g x) (𝓝[>] 0) (𝓝 (lineDeriv ℝ f x v * g x))

Proof state:
E : Type u_1
inst✝⁵ : NormedAddCommGroup E
inst✝⁴ : NormedSpace ℝ E
inst✝³ : MeasurableSpace E
inst✝² : BorelSpace E
C : ℝ≥0
f g : E → ℝ
μ : Measure E
inst✝¹ : FiniteDimensional ℝ E
inst✝ : μ.IsAddHaarMeasure
hf : LipschitzWith C f
hg : Integrable g μ
v : E
t : ℝ
ht : 0 < t
x : E
⊢ ↑C * (t * ‖v‖) * |g x| = ↑C * ‖v‖ * |g x| * t

Tactic:
ring

Result:
no goals

Proof state:
E : Type u_1
inst✝⁵ : NormedAddCommGroup E
inst✝⁴ : NormedSpace ℝ E
inst✝³ : MeasurableSpace E
inst✝² : BorelSpace E
C : ℝ≥0
f g : E → ℝ
μ : Measure E
inst✝¹ : FiniteDimensional ℝ E
inst✝ : μ.IsAddHaarMeasure
hf : LipschitzWith C f
hg : Integrable g μ
v : E
t : ℝ
⊢ AEStronglyMeasurable (fun x => f (x + t • v) - f x) μ

Tactic:
apply AEStronglyMeasurable.sub _ hf.continuous.measurable.aestronglyMeasurable

Result:
E : Type u_1
inst✝⁵ : NormedAddCommGroup E
inst✝⁴ : NormedSpace ℝ E
inst✝³ : MeasurableSpace E
inst✝² : BorelSpace E
C : ℝ≥0
f g : E → ℝ
μ : Measure E
inst✝¹ : FiniteDimensional ℝ E
inst✝ : μ.IsAddHaarMeasure
hf : LipschitzWith C f
hg : Integrable g μ
v : E
t : ℝ
⊢ AEStronglyMeasurable (fun x => f (x + t • v)) μ

Proof state:
case h_bound
E : Type u_1
inst✝⁵ : NormedAddCommGroup E
inst✝⁴ : NormedSpace ℝ E
inst✝³ : MeasurableSpace E
inst✝² : BorelSpace E
C : ℝ≥0
f g : E → ℝ
μ : Measure E
inst✝¹ : FiniteDimensional ℝ E
inst✝ : μ.IsAddHaarMeasure
hf : LipschitzWith C f
hg : Integrable g μ
v : E
⊢ ∀ᶠ (n : ℝ) in 𝓝[>] 0, ∀ᵐ (a : E) ∂μ, ‖n⁻¹ • (f (a + n • v) - f a) * g a‖ ≤ ↑C * ‖v‖ * ‖g a‖

Tactic:
filter_upwards [self_mem_nhdsWithin] with t (ht : 0 < t)

Result:
case h
E : Type u_1
inst✝⁵ : NormedAddCommGroup E
inst✝⁴ : NormedSpace ℝ E
inst✝³ : MeasurableSpace E
inst✝² : BorelSpace E
C : ℝ≥0
f g : E → ℝ
μ : Measure E
inst✝¹ : FiniteDimensional ℝ E
inst✝ : μ.IsAddHaarMeasure
hf : LipschitzWith C f
hg : Integrable g μ
v : E
t : ℝ
ht : 0 < t
⊢ ∀ᵐ (a : E) ∂μ, ‖t⁻¹ • (f (a + t • v) - f a) * g a‖ ≤ ↑C * ‖v‖ * ‖g a‖

Proof state:
case hf
E : Type u_1
inst✝⁵ : NormedAddCommGroup E
inst✝⁴ : NormedSpace ℝ E
inst✝³ : MeasurableSpace E
inst✝² : BorelSpace E
C : ℝ≥0
f g : E → ℝ
μ : Measure E
inst✝¹ : FiniteDimensional ℝ E
inst✝ : μ.IsAddHaarMeasure
hf : LipschitzWith C f
hg : Integrable g μ
v : E
t : ℝ
⊢ AEMeasurable (fun x => f (x + t • v)) μ

Tactic:
exact hf.continuous.measurable.comp_aemeasurable' (aemeasurable_id'.add_const _)

Result:
no goals

Proof state:
E : Type u_1
inst✝⁵ : NormedAddCommGroup E
inst✝⁴ : NormedSpace ℝ E
inst✝³ : MeasurableSpace E
inst✝² : BorelSpace E
C : ℝ≥0
f g : E → ℝ
μ : Measure E
inst✝¹ : FiniteDimensional ℝ E
inst✝ : μ.IsAddHaarMeasure
hf : LipschitzWith C f
hg : Integrable g μ
v : E
t : ℝ
ht : 0 < t
x : E
⊢ t⁻¹ * (↑C * ‖x + t • v - x‖) * ‖g x‖ = ↑C * ‖v‖ * ‖g x‖

Tactic:
field_simp [norm_smul, abs_of_nonneg ht.le]

Result:
E : Type u_1
inst✝⁵ : NormedAddCommGroup E
inst✝⁴ : NormedSpace ℝ E
inst✝³ : MeasurableSpace E
inst✝² : BorelSpace E
C : ℝ≥0
f g : E → ℝ
μ : Measure E
inst✝¹ : FiniteDimensional ℝ E
inst✝ : μ.IsAddHaarMeasure
hf : LipschitzWith C f
hg : Integrable g μ
v : E
t : ℝ
ht : 0 < t
x : E
⊢ ↑C * (t * ‖v‖) * |g x| = ↑C * ‖v‖ * |g x| * t

Proof state:
case h.h
E : Type u_1
inst✝⁵ : NormedAddCommGroup E
inst✝⁴ : NormedSpace ℝ E
inst✝³ : MeasurableSpace E
inst✝² : BorelSpace E
C : ℝ≥0
f g : E → ℝ
μ : Measure E
inst✝¹ : FiniteDimensional ℝ E
inst✝ : μ.IsAddHaarMeasure
hf : LipschitzWith C f
hg : Integrable g μ
v : E
t : ℝ
ht : 0 < t
x : E
⊢ ‖f (x + t • v) - f x‖ ≤ ↑C * ‖x + t • v - x‖

Tactic:
exact LipschitzWith.norm_sub_le hf (x + t • v) x

Result:
no goals

Proof state:
E : Type u_1
inst✝⁵ : NormedAddCommGroup E
inst✝⁴ : NormedSpace ℝ E
inst✝³ : MeasurableSpace E
inst✝² : BorelSpace E
C : ℝ≥0
f g : E → ℝ
μ : Measure E
inst✝¹ : FiniteDimensional ℝ E
inst✝ : μ.IsAddHaarMeasure
hf : LipschitzWith C f
hg : Integrable g μ
v : E
t : ℝ
⊢ AEStronglyMeasurable (fun x => f (x + t • v)) μ

Tactic:
apply AEMeasurable.aestronglyMeasurable

Result:
case hf
E : Type u_1
inst✝⁵ : NormedAddCommGroup E
inst✝⁴ : NormedSpace ℝ E
inst✝³ : MeasurableSpace E
inst✝² : BorelSpace E
C : ℝ≥0
f g : E → ℝ
μ : Measure E
inst✝¹ : FiniteDimensional ℝ E
inst✝ : μ.IsAddHaarMeasure
hf : LipschitzWith C f
hg : Integrable g μ
v : E
t : ℝ
⊢ AEMeasurable (fun x => f (x + t • v)) μ

Proof state:
case h
E : Type u_1
inst✝⁵ : NormedAddCommGroup E
inst✝⁴ : NormedSpace ℝ E
inst✝³ : MeasurableSpace E
inst✝² : BorelSpace E
C : ℝ≥0
f g : E → ℝ
μ : Measure E
inst✝¹ : FiniteDimensional ℝ E
inst✝ : μ.IsAddHaarMeasure
hf : LipschitzWith C f
hg : Integrable g μ
v : E
t : ℝ
ht : 0 < t
⊢ ∀ᵐ (a : E) ∂μ, ‖t⁻¹ • (f (a + t • v) - f a) * g a‖ ≤ ↑C * ‖v‖ * ‖g a‖

Tactic:
filter_upwards with x

Result:
case h.h
E : Type u_1
inst✝⁵ : NormedAddCommGroup E
inst✝⁴ : NormedSpace ℝ E
inst✝³ : MeasurableSpace E
inst✝² : BorelSpace E
C : ℝ≥0
f g : E → ℝ
μ : Measure E
inst✝¹ : FiniteDimensional ℝ E
inst✝ : μ.IsAddHaarMeasure
hf : LipschitzWith C f
hg : Integrable g μ
v : E
t : ℝ
ht : 0 < t
x : E
⊢ ‖t⁻¹ • (f (x + t • v) - f x) * g x‖ ≤ ↑C * ‖v‖ * ‖g x‖

Proof state:
case h
E : Type u_1
inst✝⁵ : NormedAddCommGroup E
inst✝⁴ : NormedSpace ℝ E
inst✝³ : MeasurableSpace E
inst✝² : BorelSpace E
C : ℝ≥0
f g : E → ℝ
μ : Measure E
inst✝¹ : FiniteDimensional ℝ E
inst✝ : μ.IsAddHaarMeasure
hf : LipschitzWith C f
hg : Integrable g μ
v x : E
hx : LineDifferentiableAt ℝ f x v
⊢ Tendsto (fun n => n⁻¹ • (f (x + n • v) - f x) * g x) (𝓝[>] 0) (𝓝 (lineDeriv ℝ f x v * g x))

Tactic:
exact hx.hasLineDerivAt.tendsto_slope_zero_right.mul tendsto_const_nhds

Result:
no goals

Proof state:
case hF_meas
E : Type u_1
inst✝⁵ : NormedAddCommGroup E
inst✝⁴ : NormedSpace ℝ E
inst✝³ : MeasurableSpace E
inst✝² : BorelSpace E
C : ℝ≥0
f g : E → ℝ
μ : Measure E
inst✝¹ : FiniteDimensional ℝ E
inst✝ : μ.IsAddHaarMeasure
hf : LipschitzWith C f
hg : Integrable g μ
v : E
⊢ ∀ᶠ (n : ℝ) in 𝓝[>] 0, AEStronglyMeasurable (fun a => n⁻¹ • (f (a + n • v) - f a) * g a) μ

Tactic:
filter_upwards with t

Result:
case hF_meas.h
E : Type u_1
inst✝⁵ : NormedAddCommGroup E
inst✝⁴ : NormedSpace ℝ E
inst✝³ : MeasurableSpace E
inst✝² : BorelSpace E
C : ℝ≥0
f g : E → ℝ
μ : Measure E
inst✝¹ : FiniteDimensional ℝ E
inst✝ : μ.IsAddHaarMeasure
hf : LipschitzWith C f
hg : Integrable g μ
v : E
t : ℝ
⊢ AEStronglyMeasurable (fun a => t⁻¹ • (f (a + t • v) - f a) * g a) μ