-- Mathlib/Analysis/Calculus/FDeriv/Extend.lean
theorem hasDerivWithinAt_Iic_of_tendsto_deriv {s : Set ℝ} {e : E} {a : ℝ}
    {f : ℝ → E} (f_diff : DifferentiableOn ℝ f s) (f_lim : ContinuousWithinAt f s a)
    (hs : s ∈ 𝓝[<] a) (f_lim' : Tendsto (fun x => deriv f x) (𝓝[<] a) (𝓝 e)) :
    HasDerivWithinAt f e (Iic a) a

Proof state:
case intro.intro
E : Type u_1
inst✝¹ : NormedAddCommGroup E
inst✝ : NormedSpace ℝ E
s : Set ℝ
e : E
a : ℝ
f : ℝ → E
f_diff : DifferentiableOn ℝ f s
f_lim : ContinuousWithinAt f s a
hs : s ∈ 𝓝[<] a
f_lim' : Tendsto (fun x => deriv f x) (𝓝[<] a) (𝓝 e)
b : ℝ
ba : b ∈ Iio a
sab : Ico b a ⊆ s
t : Set ℝ := Ioo b a
ts : t ⊆ s
t_diff : DifferentiableOn ℝ f t
⊢ HasDerivWithinAt f e (Iic a) a

Tactic:
have t_conv : Convex ℝ t := convex_Ioo b a

Result:
case intro.intro
E : Type u_1
inst✝¹ : NormedAddCommGroup E
inst✝ : NormedSpace ℝ E
s : Set ℝ
e : E
a : ℝ
f : ℝ → E
f_diff : DifferentiableOn ℝ f s
f_lim : ContinuousWithinAt f s a
hs : s ∈ 𝓝[<] a
f_lim' : Tendsto (fun x => deriv f x) (𝓝[<] a) (𝓝 e)
b : ℝ
ba : b ∈ Iio a
sab : Ico b a ⊆ s
t : Set ℝ := Ioo b a
ts : t ⊆ s
t_diff : DifferentiableOn ℝ f t
t_conv : Convex ℝ t
⊢ HasDerivWithinAt f e (Iic a) a

Proof state:
case intro.intro
E : Type u_1
inst✝¹ : NormedAddCommGroup E
inst✝ : NormedSpace ℝ E
s : Set ℝ
e : E
a : ℝ
f : ℝ → E
f_diff : DifferentiableOn ℝ f s
f_lim : ContinuousWithinAt f s a
hs : s ∈ 𝓝[<] a
f_lim' : Tendsto (fun x => deriv f x) (𝓝[<] a) (𝓝 e)
b : ℝ
ba : b ∈ Iio a
sab : Ico b a ⊆ s
t : Set ℝ := Ioo b a
ts : t ⊆ s
t_diff : DifferentiableOn ℝ f t
t_conv : Convex ℝ t
t_open : IsOpen t
t_closure : closure t = Icc b a
t_cont : ∀ y ∈ closure t, ContinuousWithinAt f t y
t_diff' : Tendsto (fun x => fderiv ℝ f x) (𝓝[t] a) (𝓝 (smulRight 1 e))
this : HasDerivWithinAt f e (Icc b a) a
⊢ HasDerivWithinAt f e (Iic a) a

Tactic:
exact this.mono_of_mem_nhdsWithin (Icc_mem_nhdsLE ba)

Result:
no goals

Proof state:
E : Type u_1
inst✝¹ : NormedAddCommGroup E
inst✝ : NormedSpace ℝ E
s : Set ℝ
e : E
a : ℝ
f : ℝ → E
f_diff : DifferentiableOn ℝ f s
f_lim : ContinuousWithinAt f s a
hs : s ∈ 𝓝[<] a
f_lim' : Tendsto (fun x => deriv f x) (𝓝[<] a) (𝓝 e)
b : ℝ
ba : b ∈ Iio a
sab : Ico b a ⊆ s
t : Set ℝ := Ioo b a
ts : t ⊆ s
t_diff : DifferentiableOn ℝ f t
t_conv : Convex ℝ t
t_open : IsOpen t
t_closure : closure t = Icc b a
t_cont : ∀ y ∈ closure t, ContinuousWithinAt f t y
t_diff' : Tendsto (fun x => fderiv ℝ f x) (𝓝[t] a) (𝓝 (smulRight 1 e))
⊢ HasFDerivWithinAt f (smulRight 1 e) (closure t) a

Tactic:
exact hasFDerivWithinAt_closure_of_tendsto_fderiv t_diff t_conv t_open t_cont t_diff'

Result:
no goals

Proof state:
case intro.intro
E : Type u_1
inst✝¹ : NormedAddCommGroup E
inst✝ : NormedSpace ℝ E
s : Set ℝ
e : E
a : ℝ
f : ℝ → E
f_diff : DifferentiableOn ℝ f s
f_lim : ContinuousWithinAt f s a
hs : s ∈ 𝓝[<] a
f_lim' : Tendsto (fun x => deriv f x) (𝓝[<] a) (𝓝 e)
b : ℝ
ba : b ∈ Iio a
sab : Ico b a ⊆ s
t : Set ℝ := Ioo b a
ts : t ⊆ s
t_diff : DifferentiableOn ℝ f t
t_conv : Convex ℝ t
t_open : IsOpen t
t_closure : closure t = Icc b a
t_cont : ∀ y ∈ closure t, ContinuousWithinAt f t y
⊢ HasDerivWithinAt f e (Iic a) a

Tactic:
have t_diff' : Tendsto (fun x => fderiv ℝ f x) (𝓝[t] a) (𝓝 (smulRight (1 : ℝ →L[ℝ] ℝ) e)) := by
  simp only [deriv_fderiv.symm]
  exact Tendsto.comp
    (isBoundedBilinearMap_smulRight : IsBoundedBilinearMap ℝ _).continuous_right.continuousAt
    (tendsto_nhdsWithin_mono_left Ioo_subset_Iio_self f_lim')

Result:
case intro.intro
E : Type u_1
inst✝¹ : NormedAddCommGroup E
inst✝ : NormedSpace ℝ E
s : Set ℝ
e : E
a : ℝ
f : ℝ → E
f_diff : DifferentiableOn ℝ f s
f_lim : ContinuousWithinAt f s a
hs : s ∈ 𝓝[<] a
f_lim' : Tendsto (fun x => deriv f x) (𝓝[<] a) (𝓝 e)
b : ℝ
ba : b ∈ Iio a
sab : Ico b a ⊆ s
t : Set ℝ := Ioo b a
ts : t ⊆ s
t_diff : DifferentiableOn ℝ f t
t_conv : Convex ℝ t
t_open : IsOpen t
t_closure : closure t = Icc b a
t_cont : ∀ y ∈ closure t, ContinuousWithinAt f t y
t_diff' : Tendsto (fun x => fderiv ℝ f x) (𝓝[t] a) (𝓝 (smulRight 1 e))
⊢ HasDerivWithinAt f e (Iic a) a

Proof state:
case pos
E : Type u_1
inst✝¹ : NormedAddCommGroup E
inst✝ : NormedSpace ℝ E
s : Set ℝ
e : E
a : ℝ
f : ℝ → E
f_diff : DifferentiableOn ℝ f s
f_lim : ContinuousWithinAt f s a
hs : s ∈ 𝓝[<] a
f_lim' : Tendsto (fun x => deriv f x) (𝓝[<] a) (𝓝 e)
b : ℝ
ba : b ∈ Iio a
sab : Ico b a ⊆ s
t : Set ℝ := Ioo b a
ts : t ⊆ s
t_diff : DifferentiableOn ℝ f t
t_conv : Convex ℝ t
t_open : IsOpen t
t_closure : closure t = Icc b a
y : ℝ
hy : y ∈ Icc b a
h : y = a
⊢ ContinuousWithinAt f t y

Tactic:
rw [h]

Result:
case pos
E : Type u_1
inst✝¹ : NormedAddCommGroup E
inst✝ : NormedSpace ℝ E
s : Set ℝ
e : E
a : ℝ
f : ℝ → E
f_diff : DifferentiableOn ℝ f s
f_lim : ContinuousWithinAt f s a
hs : s ∈ 𝓝[<] a
f_lim' : Tendsto (fun x => deriv f x) (𝓝[<] a) (𝓝 e)
b : ℝ
ba : b ∈ Iio a
sab : Ico b a ⊆ s
t : Set ℝ := Ioo b a
ts : t ⊆ s
t_diff : DifferentiableOn ℝ f t
t_conv : Convex ℝ t
t_open : IsOpen t
t_closure : closure t = Icc b a
y : ℝ
hy : y ∈ Icc b a
h : y = a
⊢ ContinuousWithinAt f t a

Proof state:
E : Type u_1
inst✝¹ : NormedAddCommGroup E
inst✝ : NormedSpace ℝ E
s : Set ℝ
e : E
a : ℝ
f : ℝ → E
f_diff : DifferentiableOn ℝ f s
f_lim : ContinuousWithinAt f s a
hs : s ∈ 𝓝[<] a
f_lim' : Tendsto (fun x => deriv f x) (𝓝[<] a) (𝓝 e)
b : ℝ
ba : b ∈ Iio a
sab : Ico b a ⊆ s
t : Set ℝ := Ioo b a
ts : t ⊆ s
t_diff : DifferentiableOn ℝ f t
t_conv : Convex ℝ t
t_open : IsOpen t
t_closure : closure t = Icc b a
t_cont : ∀ y ∈ closure t, ContinuousWithinAt f t y
t_diff' : Tendsto (fun x => fderiv ℝ f x) (𝓝[t] a) (𝓝 (smulRight 1 e))
⊢ HasDerivWithinAt f e (Icc b a) a

Tactic:
rw [hasDerivWithinAt_iff_hasFDerivWithinAt, ← t_closure]

Result:
E : Type u_1
inst✝¹ : NormedAddCommGroup E
inst✝ : NormedSpace ℝ E
s : Set ℝ
e : E
a : ℝ
f : ℝ → E
f_diff : DifferentiableOn ℝ f s
f_lim : ContinuousWithinAt f s a
hs : s ∈ 𝓝[<] a
f_lim' : Tendsto (fun x => deriv f x) (𝓝[<] a) (𝓝 e)
b : ℝ
ba : b ∈ Iio a
sab : Ico b a ⊆ s
t : Set ℝ := Ioo b a
ts : t ⊆ s
t_diff : DifferentiableOn ℝ f t
t_conv : Convex ℝ t
t_open : IsOpen t
t_closure : closure t = Icc b a
t_cont : ∀ y ∈ closure t, ContinuousWithinAt f t y
t_diff' : Tendsto (fun x => fderiv ℝ f x) (𝓝[t] a) (𝓝 (smulRight 1 e))
⊢ HasFDerivWithinAt f (smulRight 1 e) (closure t) a

Proof state:
E : Type u_1
inst✝¹ : NormedAddCommGroup E
inst✝ : NormedSpace ℝ E
s : Set ℝ
e : E
a : ℝ
f : ℝ → E
f_diff : DifferentiableOn ℝ f s
f_lim : ContinuousWithinAt f s a
hs : s ∈ 𝓝[<] a
f_lim' : Tendsto (fun x => deriv f x) (𝓝[<] a) (𝓝 e)
b : ℝ
ba : b ∈ Iio a
sab : Ico b a ⊆ s
t : Set ℝ := Ioo b a
ts : t ⊆ s
t_diff : DifferentiableOn ℝ f t
t_conv : Convex ℝ t
t_open : IsOpen t
t_closure : closure t = Icc b a
⊢ ∀ y ∈ closure t, ContinuousWithinAt f t y

Tactic:
rw [t_closure]

Result:
E : Type u_1
inst✝¹ : NormedAddCommGroup E
inst✝ : NormedSpace ℝ E
s : Set ℝ
e : E
a : ℝ
f : ℝ → E
f_diff : DifferentiableOn ℝ f s
f_lim : ContinuousWithinAt f s a
hs : s ∈ 𝓝[<] a
f_lim' : Tendsto (fun x => deriv f x) (𝓝[<] a) (𝓝 e)
b : ℝ
ba : b ∈ Iio a
sab : Ico b a ⊆ s
t : Set ℝ := Ioo b a
ts : t ⊆ s
t_diff : DifferentiableOn ℝ f t
t_conv : Convex ℝ t
t_open : IsOpen t
t_closure : closure t = Icc b a
⊢ ∀ y ∈ Icc b a, ContinuousWithinAt f t y

Proof state:
E : Type u_1
inst✝¹ : NormedAddCommGroup E
inst✝ : NormedSpace ℝ E
s : Set ℝ
e : E
a : ℝ
f : ℝ → E
f_diff : DifferentiableOn ℝ f s
f_lim : ContinuousWithinAt f s a
hs : s ∈ 𝓝[<] a
f_lim' : Tendsto (fun x => deriv f x) (𝓝[<] a) (𝓝 e)
b : ℝ
ba : b ∈ Iio a
sab : Ico b a ⊆ s
t : Set ℝ := Ioo b a
ts : t ⊆ s
t_diff : DifferentiableOn ℝ f t
t_conv : Convex ℝ t
t_open : IsOpen t
t_closure : closure t = Icc b a
t_cont : ∀ y ∈ closure t, ContinuousWithinAt f t y
⊢ Tendsto (fun x => smulRight 1 (deriv f x)) (𝓝[t] a) (𝓝 (smulRight 1 e))

Tactic:
exact Tendsto.comp
  (isBoundedBilinearMap_smulRight : IsBoundedBilinearMap ℝ _).continuous_right.continuousAt
  (tendsto_nhdsWithin_mono_left Ioo_subset_Iio_self f_lim')

Result:
no goals