Module: Mathlib.Analysis.Calculus.LineDeriv.IntegrationByParts

Goal state before:
pp: E : Type u_1
F : Type u_2
G : Type u_3
W : Type u_4
inst✝⁹ : NormedAddCommGroup E
inst✝⁸ : NormedSpace ℝ E
inst✝⁷ : NormedAddCommGroup F
inst✝⁶ : NormedSpace ℝ F
inst✝⁵ : NormedAddCommGroup G
inst✝⁴ : NormedSpace ℝ G
inst✝³ : NormedAddCommGroup W
inst✝² : NormedSpace ℝ W
inst✝¹ : MeasurableSpace E
μ : Measure E
inst✝ : SigmaFinite μ
f f' : E × ℝ → F
g g' : E × ℝ → G
B : F →L[ℝ] G →L[ℝ] W
hf'g : Integrable (fun x ↦ (B (f' x)) (g x)) (μ.prod volume)
hfg' : Integrable (fun x ↦ (B (f x)) (g' x)) (μ.prod volume)
hfg : Integrable (fun x ↦ (B (f x)) (g x)) (μ.prod volume)
hf : ∀ x ∈ tsupport g, HasLineDerivAt ℝ f (f' x) x (0, 1)
hg : ∀ x ∈ tsupport f, HasLineDerivAt ℝ g (g' x) x (0, 1)
x : E
hf'gx : Integrable (fun y ↦ (B (f' (x, y))) (g (x, y))) volume
hfg'x : Integrable (fun y ↦ (B (f (x, y))) (g' (x, y))) volume
hfgx : Integrable (fun y ↦ (B (f (x, y))) (g (x, y))) volume
⊢ ∀ x_1 ∈ tsupport fun x_2 ↦ g (x, x_2), HasDerivAt (fun x_2 ↦ f (x, x_2)) (f' (x, x_1)) x_1

pp: E : Type u_1
F : Type u_2
G : Type u_3
W : Type u_4
inst✝⁹ : NormedAddCommGroup E
inst✝⁸ : NormedSpace ℝ E
inst✝⁷ : NormedAddCommGroup F
inst✝⁶ : NormedSpace ℝ F
inst✝⁵ : NormedAddCommGroup G
inst✝⁴ : NormedSpace ℝ G
inst✝³ : NormedAddCommGroup W
inst✝² : NormedSpace ℝ W
inst✝¹ : MeasurableSpace E
μ : Measure E
inst✝ : SigmaFinite μ
f f' : E × ℝ → F
g g' : E × ℝ → G
B : F →L[ℝ] G →L[ℝ] W
hf'g : Integrable (fun x ↦ (B (f' x)) (g x)) (μ.prod volume)
hfg' : Integrable (fun x ↦ (B (f x)) (g' x)) (μ.prod volume)
hfg : Integrable (fun x ↦ (B (f x)) (g x)) (μ.prod volume)
hf : ∀ x ∈ tsupport g, HasLineDerivAt ℝ f (f' x) x (0, 1)
hg : ∀ x ∈ tsupport f, HasLineDerivAt ℝ g (g' x) x (0, 1)
x : E
hf'gx : Integrable (fun y ↦ (B (f' (x, y))) (g (x, y))) volume
hfg'x : Integrable (fun y ↦ (B (f (x, y))) (g' (x, y))) volume
hfgx : Integrable (fun y ↦ (B (f (x, y))) (g (x, y))) volume
⊢ ∀ x_1 ∈ tsupport fun x_2 ↦ f (x, x_2), HasDerivAt (fun x_2 ↦ g (x, x_2)) (g' (x, x_1)) x_1

Tactic:
· intro t ht
      have : (x, t) ∈ tsupport g :=
        tsupport_comp_subset_preimage (f := fun y ↦ (x, y)) g (by fun_prop) ht
      convert! (hf (x, t) this).scomp_of_eq t ((hasDerivAt_id t).add (hasDerivAt_const t (-t)))
        (by simp) <;> simp

Goal state after:
E : Type u_1
F : Type u_2
G : Type u_3
W : Type u_4
inst✝⁹ : NormedAddCommGroup E
inst✝⁸ : NormedSpace ℝ E
inst✝⁷ : NormedAddCommGroup F
inst✝⁶ : NormedSpace ℝ F
inst✝⁵ : NormedAddCommGroup G
inst✝⁴ : NormedSpace ℝ G
inst✝³ : NormedAddCommGroup W
inst✝² : NormedSpace ℝ W
inst✝¹ : MeasurableSpace E
μ : Measure E
inst✝ : SigmaFinite μ
f f' : E × ℝ → F
g g' : E × ℝ → G
B : F →L[ℝ] G →L[ℝ] W
hf'g : Integrable (fun x ↦ (B (f' x)) (g x)) (μ.prod volume)
hfg' : Integrable (fun x ↦ (B (f x)) (g' x)) (μ.prod volume)
hfg : Integrable (fun x ↦ (B (f x)) (g x)) (μ.prod volume)
hf : ∀ x ∈ tsupport g, HasLineDerivAt ℝ f (f' x) x (0, 1)
hg : ∀ x ∈ tsupport f, HasLineDerivAt ℝ g (g' x) x (0, 1)
x : E
hf'gx : Integrable (fun y ↦ (B (f' (x, y))) (g (x, y))) volume
hfg'x : Integrable (fun y ↦ (B (f (x, y))) (g' (x, y))) volume
hfgx : Integrable (fun y ↦ (B (f (x, y))) (g (x, y))) volume
⊢ ∀ x_1 ∈ tsupport fun x_2 ↦ f (x, x_2), HasDerivAt (fun x_2 ↦ g (x, x_2)) (g' (x, x_1)) x_1