l3lab/ntp-mathlib huggingface dataset:
theorem ae_eq_zero_of_forall_dual_of_isSeparable [NormedAddCommGroup E] [NormedSpace 𝕜 E]
    {t : Set E} (ht : TopologicalSpace.IsSeparable t) {f : α → E}
    (hf : ∀ c : Dual 𝕜 E, (fun x => ⟪f x, c⟫) =ᵐ[μ] 0) (h't : ∀ᵐ x ∂μ, f x ∈ t) : f =ᵐ[μ] 0 := by
  rcases ht with ⟨d, d_count, hd⟩
  haveI : Encodable d := d_count.toEncodable
  have : ∀ x : d, ∃ g : E →L[𝕜] 𝕜, ‖g‖ ≤ 1 ∧ g x = ‖(x : E)‖ :=
    fun x => exists_dual_vector'' 𝕜 (x : E)
  choose s hs using this
  have A : ∀ a : E, a ∈ t → (∀ x, ⟪a, s x⟫ = (0 : 𝕜)) → a = 0 := by
    intro a hat ha
    contrapose! ha
    have a_pos : 0 < ‖a‖ := by simp only [ha, norm_pos_iff, Ne.def, not_false_iff]
    have a_mem : a ∈ closure d := hd hat
    obtain ⟨x, hx⟩ : ∃ x : d, dist a x < ‖a‖ / 2 := by
      rcases Metric.mem_closure_iff.1 a_mem (‖a‖ / 2) (half_pos a_pos) with ⟨x, h'x, hx⟩
      exact ⟨⟨x, h'x⟩, hx⟩
    use x
    have I : ‖a‖ / 2 < ‖(x : E)‖ := by
      have : ‖a‖ ≤ ‖(x : E)‖ + ‖a - x‖ := norm_le_insert' _ _
      have : ‖a - x‖ < ‖a‖ / 2 := by rwa [dist_eq_norm] at hx
      linarith
    intro h
    

Proof state:
case h
α : Type u_1
E : Type u_2
𝕜 : Type u_3
m : MeasurableSpace α
μ : Measure α
inst✝² : IsROrC 𝕜
inst✝¹ : NormedAddCommGroup E
inst✝ : NormedSpace 𝕜 E
t : Set E
f : α → E
hf : ∀ (c : Dual 𝕜 E), (fun x => c (f x)) =ᵐ[μ] 0
h't : ∀ᵐ (x : α) ∂μ, f x ∈ t
d : Set E
d_count : Set.Countable d
hd : t ⊆ closure d
this : Encodable ↑d
s : ↑d → E →L[𝕜] 𝕜
hs : ∀ (x : ↑d), ‖s x‖ ≤ 1 ∧ (s x) ↑x = ↑‖↑x‖
a : E
hat : a ∈ t
ha : a ≠ 0
a_pos : 0 < ‖a‖
a_mem : a ∈ closure d
x : ↑d
hx : dist a ↑x < ‖a‖ / 2
I : ‖a‖ / 2 < ‖↑x‖
h : (s x) a = 0
⊢ False

Next tactic:
apply lt_irrefl ‖s x x‖
theorem ae_eq_zero_of_forall_dual_of_isSeparable [NormedAddCommGroup E] [NormedSpace 𝕜 E]
    {t : Set E} (ht : TopologicalSpace.IsSeparable t) {f : α → E}
    (hf : ∀ c : Dual 𝕜 E, (fun x => ⟪f x, c⟫) =ᵐ[μ] 0) (h't : ∀ᵐ x ∂μ, f x ∈ t) : f =ᵐ[μ] 0 := by
  rcases ht with ⟨d, d_count, hd⟩
  haveI : Encodable d := d_count.toEncodable
  have : ∀ x : d, ∃ g : E →L[𝕜] 𝕜, ‖g‖ ≤ 1 ∧ g x = ‖(x : E)‖ :=
    fun x => exists_dual_vector'' 𝕜 (x : E)
  choose s hs using this
  have A : ∀ a : E, a ∈ t → (∀ x, ⟪a, s x⟫ = (0 : 𝕜)) → a = 0 := by
    intro a hat ha
    contrapose! ha
    have a_pos : 0 < ‖a‖ := by simp only [ha, norm_pos_iff, Ne.def, not_false_iff]
    have a_mem : a ∈ closure d := hd hat
    obtain ⟨x, hx⟩ : ∃ x : d, dist a x < ‖a‖ / 2 := by
      rcases Metric.mem_closure_iff.1 a_mem (‖a‖ / 2) (half_pos a_pos) with ⟨x, h'x, hx⟩
      exact ⟨⟨x, h'x⟩, hx⟩
    use x
    have I : ‖a‖ / 2 < ‖(x : E)‖ := by
      have : ‖a‖ ≤ ‖(x : E)‖ + ‖a - x‖ := norm_le_insert' _ _
      have : ‖a - x‖ < ‖a‖ / 2 := by rwa [dist_eq_norm] at hx
      linarith
    intro h
    apply lt_irrefl ‖s x x‖
    

Proof state:
case h
α : Type u_1
E : Type u_2
𝕜 : Type u_3
m : MeasurableSpace α
μ : Measure α
inst✝² : IsROrC 𝕜
inst✝¹ : NormedAddCommGroup E
inst✝ : NormedSpace 𝕜 E
t : Set E
f : α → E
hf : ∀ (c : Dual 𝕜 E), (fun x => c (f x)) =ᵐ[μ] 0
h't : ∀ᵐ (x : α) ∂μ, f x ∈ t
d : Set E
d_count : Set.Countable d
hd : t ⊆ closure d
this : Encodable ↑d
s : ↑d → E →L[𝕜] 𝕜
hs : ∀ (x : ↑d), ‖s x‖ ≤ 1 ∧ (s x) ↑x = ↑‖↑x‖
a : E
hat : a ∈ t
ha : a ≠ 0
a_pos : 0 < ‖a‖
a_mem : a ∈ closure d
x : ↑d
hx : dist a ↑x < ‖a‖ / 2
I : ‖a‖ / 2 < ‖↑x‖
h : (s x) a = 0
⊢ ‖(s x) ↑x‖ < ‖(s x) ↑x‖

Next tactic:
calc
      ‖s x x‖ = ‖s x (x - a)‖ := by simp only [h, sub_zero, ContinuousLinearMap.map_sub]
      _ ≤ 1 * ‖(x : E) - a‖ := (ContinuousLinearMap.le_of_op_norm_le _ (hs x).1 _)
      _ < ‖a‖ / 2 := by rw [one_mul]; rwa [dist_eq_norm'] at hx
      _ < ‖(x : E)‖ := I
      _ = ‖s x x‖ := by rw [(hs x).2, IsROrC.norm_coe_norm]
theorem ae_eq_zero_of_forall_dual_of_isSeparable [NormedAddCommGroup E] [NormedSpace 𝕜 E]
    {t : Set E} (ht : TopologicalSpace.IsSeparable t) {f : α → E}
    (hf : ∀ c : Dual 𝕜 E, (fun x => ⟪f x, c⟫) =ᵐ[μ] 0) (h't : ∀ᵐ x ∂μ, f x ∈ t) : f =ᵐ[μ] 0 := by
  rcases ht with ⟨d, d_count, hd⟩
  haveI : Encodable d := d_count.toEncodable
  have : ∀ x : d, ∃ g : E →L[𝕜] 𝕜, ‖g‖ ≤ 1 ∧ g x = ‖(x : E)‖ :=
    fun x => exists_dual_vector'' 𝕜 (x : E)
  choose s hs using this
  have A : ∀ a : E, a ∈ t → (∀ x, ⟪a, s x⟫ = (0 : 𝕜)) → a = 0 := by
    intro a hat ha
    contrapose! ha
    have a_pos : 0 < ‖a‖ := by simp only [ha, norm_pos_iff, Ne.def, not_false_iff]
    have a_mem : a ∈ closure d := hd hat
    obtain ⟨x, hx⟩ : ∃ x : d, dist a x < ‖a‖ / 2 := by
      rcases Metric.mem_closure_iff.1 a_mem (‖a‖ / 2) (half_pos a_pos) with ⟨x, h'x, hx⟩
      exact ⟨⟨x, h'x⟩, hx⟩
    use x
    have I : ‖a‖ / 2 < ‖(x : E)‖ := by
      have : ‖a‖ ≤ ‖(x : E)‖ + ‖a - x‖ := norm_le_insert' _ _
      have : ‖a - x‖ < ‖a‖ / 2 := by rwa [dist_eq_norm] at hx
      linarith
    intro h
    apply lt_irrefl ‖s x x‖
    calc
      ‖s x x‖ = ‖s x (x - a)‖ := by 

Proof state:
α : Type u_1
E : Type u_2
𝕜 : Type u_3
m : MeasurableSpace α
μ : Measure α
inst✝² : IsROrC 𝕜
inst✝¹ : NormedAddCommGroup E
inst✝ : NormedSpace 𝕜 E
t : Set E
f : α → E
hf : ∀ (c : Dual 𝕜 E), (fun x => c (f x)) =ᵐ[μ] 0
h't : ∀ᵐ (x : α) ∂μ, f x ∈ t
d : Set E
d_count : Set.Countable d
hd : t ⊆ closure d
this : Encodable ↑d
s : ↑d → E →L[𝕜] 𝕜
hs : ∀ (x : ↑d), ‖s x‖ ≤ 1 ∧ (s x) ↑x = ↑‖↑x‖
a : E
hat : a ∈ t
ha : a ≠ 0
a_pos : 0 < ‖a‖
a_mem : a ∈ closure d
x : ↑d
hx : dist a ↑x < ‖a‖ / 2
I : ‖a‖ / 2 < ‖↑x‖
h : (s x) a = 0
⊢ ‖(s x) ↑x‖ = ‖(s x) (↑x - a)‖

Next tactic:
simp only [h, sub_zero, ContinuousLinearMap.map_sub]
theorem ae_eq_zero_of_forall_dual_of_isSeparable [NormedAddCommGroup E] [NormedSpace 𝕜 E]
    {t : Set E} (ht : TopologicalSpace.IsSeparable t) {f : α → E}
    (hf : ∀ c : Dual 𝕜 E, (fun x => ⟪f x, c⟫) =ᵐ[μ] 0) (h't : ∀ᵐ x ∂μ, f x ∈ t) : f =ᵐ[μ] 0 := by
  rcases ht with ⟨d, d_count, hd⟩
  haveI : Encodable d := d_count.toEncodable
  have : ∀ x : d, ∃ g : E →L[𝕜] 𝕜, ‖g‖ ≤ 1 ∧ g x = ‖(x : E)‖ :=
    fun x => exists_dual_vector'' 𝕜 (x : E)
  choose s hs using this
  have A : ∀ a : E, a ∈ t → (∀ x, ⟪a, s x⟫ = (0 : 𝕜)) → a = 0 := by
    intro a hat ha
    contrapose! ha
    have a_pos : 0 < ‖a‖ := by simp only [ha, norm_pos_iff, Ne.def, not_false_iff]
    have a_mem : a ∈ closure d := hd hat
    obtain ⟨x, hx⟩ : ∃ x : d, dist a x < ‖a‖ / 2 := by
      rcases Metric.mem_closure_iff.1 a_mem (‖a‖ / 2) (half_pos a_pos) with ⟨x, h'x, hx⟩
      exact ⟨⟨x, h'x⟩, hx⟩
    use x
    have I : ‖a‖ / 2 < ‖(x : E)‖ := by
      have : ‖a‖ ≤ ‖(x : E)‖ + ‖a - x‖ := norm_le_insert' _ _
      have : ‖a - x‖ < ‖a‖ / 2 := by rwa [dist_eq_norm] at hx
      linarith
    intro h
    apply lt_irrefl ‖s x x‖
    calc
      ‖s x x‖ = ‖s x (x - a)‖ := by simp only [h, sub_zero, ContinuousLinearMap.map_sub]
      _ ≤ 1 * ‖(x : E) - a‖ := (ContinuousLinearMap.le_of_op_norm_le _ (hs x).1 _)
      _ < ‖a‖ / 2 := by 

Proof state:
α : Type u_1
E : Type u_2
𝕜 : Type u_3
m : MeasurableSpace α
μ : Measure α
inst✝² : IsROrC 𝕜
inst✝¹ : NormedAddCommGroup E
inst✝ : NormedSpace 𝕜 E
t : Set E
f : α → E
hf : ∀ (c : Dual 𝕜 E), (fun x => c (f x)) =ᵐ[μ] 0
h't : ∀ᵐ (x : α) ∂μ, f x ∈ t
d : Set E
d_count : Set.Countable d
hd : t ⊆ closure d
this : Encodable ↑d
s : ↑d → E →L[𝕜] 𝕜
hs : ∀ (x : ↑d), ‖s x‖ ≤ 1 ∧ (s x) ↑x = ↑‖↑x‖
a : E
hat : a ∈ t
ha : a ≠ 0
a_pos : 0 < ‖a‖
a_mem : a ∈ closure d
x : ↑d
hx : dist a ↑x < ‖a‖ / 2
I : ‖a‖ / 2 < ‖↑x‖
h : (s x) a = 0
⊢ 1 * ‖↑x - a‖ < ‖a‖ / 2

Next tactic:
rw [one_mul]
theorem ae_eq_zero_of_forall_dual_of_isSeparable [NormedAddCommGroup E] [NormedSpace 𝕜 E]
    {t : Set E} (ht : TopologicalSpace.IsSeparable t) {f : α → E}
    (hf : ∀ c : Dual 𝕜 E, (fun x => ⟪f x, c⟫) =ᵐ[μ] 0) (h't : ∀ᵐ x ∂μ, f x ∈ t) : f =ᵐ[μ] 0 := by
  rcases ht with ⟨d, d_count, hd⟩
  haveI : Encodable d := d_count.toEncodable
  have : ∀ x : d, ∃ g : E →L[𝕜] 𝕜, ‖g‖ ≤ 1 ∧ g x = ‖(x : E)‖ :=
    fun x => exists_dual_vector'' 𝕜 (x : E)
  choose s hs using this
  have A : ∀ a : E, a ∈ t → (∀ x, ⟪a, s x⟫ = (0 : 𝕜)) → a = 0 := by
    intro a hat ha
    contrapose! ha
    have a_pos : 0 < ‖a‖ := by simp only [ha, norm_pos_iff, Ne.def, not_false_iff]
    have a_mem : a ∈ closure d := hd hat
    obtain ⟨x, hx⟩ : ∃ x : d, dist a x < ‖a‖ / 2 := by
      rcases Metric.mem_closure_iff.1 a_mem (‖a‖ / 2) (half_pos a_pos) with ⟨x, h'x, hx⟩
      exact ⟨⟨x, h'x⟩, hx⟩
    use x
    have I : ‖a‖ / 2 < ‖(x : E)‖ := by
      have : ‖a‖ ≤ ‖(x : E)‖ + ‖a - x‖ := norm_le_insert' _ _
      have : ‖a - x‖ < ‖a‖ / 2 := by rwa [dist_eq_norm] at hx
      linarith
    intro h
    apply lt_irrefl ‖s x x‖
    calc
      ‖s x x‖ = ‖s x (x - a)‖ := by simp only [h, sub_zero, ContinuousLinearMap.map_sub]
      _ ≤ 1 * ‖(x : E) - a‖ := (ContinuousLinearMap.le_of_op_norm_le _ (hs x).1 _)
      _ < ‖a‖ / 2 := by rw [one_mul]; 

Proof state:
α : Type u_1
E : Type u_2
𝕜 : Type u_3
m : MeasurableSpace α
μ : Measure α
inst✝² : IsROrC 𝕜
inst✝¹ : NormedAddCommGroup E
inst✝ : NormedSpace 𝕜 E
t : Set E
f : α → E
hf : ∀ (c : Dual 𝕜 E), (fun x => c (f x)) =ᵐ[μ] 0
h't : ∀ᵐ (x : α) ∂μ, f x ∈ t
d : Set E
d_count : Set.Countable d
hd : t ⊆ closure d
this : Encodable ↑d
s : ↑d → E →L[𝕜] 𝕜
hs : ∀ (x : ↑d), ‖s x‖ ≤ 1 ∧ (s x) ↑x = ↑‖↑x‖
a : E
hat : a ∈ t
ha : a ≠ 0
a_pos : 0 < ‖a‖
a_mem : a ∈ closure d
x : ↑d
hx : dist a ↑x < ‖a‖ / 2
I : ‖a‖ / 2 < ‖↑x‖
h : (s x) a = 0
⊢ ‖↑x - a‖ < ‖a‖ / 2

Next tactic:
rwa [dist_eq_norm'] at hx
theorem ae_eq_zero_of_forall_dual_of_isSeparable [NormedAddCommGroup E] [NormedSpace 𝕜 E]
    {t : Set E} (ht : TopologicalSpace.IsSeparable t) {f : α → E}
    (hf : ∀ c : Dual 𝕜 E, (fun x => ⟪f x, c⟫) =ᵐ[μ] 0) (h't : ∀ᵐ x ∂μ, f x ∈ t) : f =ᵐ[μ] 0 := by
  rcases ht with ⟨d, d_count, hd⟩
  haveI : Encodable d := d_count.toEncodable
  have : ∀ x : d, ∃ g : E →L[𝕜] 𝕜, ‖g‖ ≤ 1 ∧ g x = ‖(x : E)‖ :=
    fun x => exists_dual_vector'' 𝕜 (x : E)
  choose s hs using this
  have A : ∀ a : E, a ∈ t → (∀ x, ⟪a, s x⟫ = (0 : 𝕜)) → a = 0 := by
    intro a hat ha
    contrapose! ha
    have a_pos : 0 < ‖a‖ := by simp only [ha, norm_pos_iff, Ne.def, not_false_iff]
    have a_mem : a ∈ closure d := hd hat
    obtain ⟨x, hx⟩ : ∃ x : d, dist a x < ‖a‖ / 2 := by
      rcases Metric.mem_closure_iff.1 a_mem (‖a‖ / 2) (half_pos a_pos) with ⟨x, h'x, hx⟩
      exact ⟨⟨x, h'x⟩, hx⟩
    use x
    have I : ‖a‖ / 2 < ‖(x : E)‖ := by
      have : ‖a‖ ≤ ‖(x : E)‖ + ‖a - x‖ := norm_le_insert' _ _
      have : ‖a - x‖ < ‖a‖ / 2 := by rwa [dist_eq_norm] at hx
      linarith
    intro h
    apply lt_irrefl ‖s x x‖
    calc
      ‖s x x‖ = ‖s x (x - a)‖ := by simp only [h, sub_zero, ContinuousLinearMap.map_sub]
      _ ≤ 1 * ‖(x : E) - a‖ := (ContinuousLinearMap.le_of_op_norm_le _ (hs x).1 _)
      _ < ‖a‖ / 2 := by rw [one_mul]; rwa [dist_eq_norm'] at hx
      _ < ‖(x : E)‖ := I
      _ = ‖s x x‖ := by 

Proof state:
α : Type u_1
E : Type u_2
𝕜 : Type u_3
m : MeasurableSpace α
μ : Measure α
inst✝² : IsROrC 𝕜
inst✝¹ : NormedAddCommGroup E
inst✝ : NormedSpace 𝕜 E
t : Set E
f : α → E
hf : ∀ (c : Dual 𝕜 E), (fun x => c (f x)) =ᵐ[μ] 0
h't : ∀ᵐ (x : α) ∂μ, f x ∈ t
d : Set E
d_count : Set.Countable d
hd : t ⊆ closure d
this : Encodable ↑d
s : ↑d → E →L[𝕜] 𝕜
hs : ∀ (x : ↑d), ‖s x‖ ≤ 1 ∧ (s x) ↑x = ↑‖↑x‖
a : E
hat : a ∈ t
ha : a ≠ 0
a_pos : 0 < ‖a‖
a_mem : a ∈ closure d
x : ↑d
hx : dist a ↑x < ‖a‖ / 2
I : ‖a‖ / 2 < ‖↑x‖
h : (s x) a = 0
⊢ ‖↑x‖ = ‖(s x) ↑x‖

Next tactic:
rw [(hs x).2, IsROrC.norm_coe_norm]
theorem ae_eq_zero_of_forall_dual_of_isSeparable [NormedAddCommGroup E] [NormedSpace 𝕜 E]
    {t : Set E} (ht : TopologicalSpace.IsSeparable t) {f : α → E}
    (hf : ∀ c : Dual 𝕜 E, (fun x => ⟪f x, c⟫) =ᵐ[μ] 0) (h't : ∀ᵐ x ∂μ, f x ∈ t) : f =ᵐ[μ] 0 := by
  rcases ht with ⟨d, d_count, hd⟩
  haveI : Encodable d := d_count.toEncodable
  have : ∀ x : d, ∃ g : E →L[𝕜] 𝕜, ‖g‖ ≤ 1 ∧ g x = ‖(x : E)‖ :=
    fun x => exists_dual_vector'' 𝕜 (x : E)
  choose s hs using this
  have A : ∀ a : E, a ∈ t → (∀ x, ⟪a, s x⟫ = (0 : 𝕜)) → a = 0 := by
    intro a hat ha
    contrapose! ha
    have a_pos : 0 < ‖a‖ := by simp only [ha, norm_pos_iff, Ne.def, not_false_iff]
    have a_mem : a ∈ closure d := hd hat
    obtain ⟨x, hx⟩ : ∃ x : d, dist a x < ‖a‖ / 2 := by
      rcases Metric.mem_closure_iff.1 a_mem (‖a‖ / 2) (half_pos a_pos) with ⟨x, h'x, hx⟩
      exact ⟨⟨x, h'x⟩, hx⟩
    use x
    have I : ‖a‖ / 2 < ‖(x : E)‖ := by
      have : ‖a‖ ≤ ‖(x : E)‖ + ‖a - x‖ := norm_le_insert' _ _
      have : ‖a - x‖ < ‖a‖ / 2 := by rwa [dist_eq_norm] at hx
      linarith
    intro h
    apply lt_irrefl ‖s x x‖
    calc
      ‖s x x‖ = ‖s x (x - a)‖ := by simp only [h, sub_zero, ContinuousLinearMap.map_sub]
      _ ≤ 1 * ‖(x : E) - a‖ := (ContinuousLinearMap.le_of_op_norm_le _ (hs x).1 _)
      _ < ‖a‖ / 2 := by rw [one_mul]; rwa [dist_eq_norm'] at hx
      _ < ‖(x : E)‖ := I
      _ = ‖s x x‖ := by rw [(hs x).2, IsROrC.norm_coe_norm]
  

Proof state:
case intro.intro
α : Type u_1
E : Type u_2
𝕜 : Type u_3
m : MeasurableSpace α
μ : Measure α
inst✝² : IsROrC 𝕜
inst✝¹ : NormedAddCommGroup E
inst✝ : NormedSpace 𝕜 E
t : Set E
f : α → E
hf : ∀ (c : Dual 𝕜 E), (fun x => c (f x)) =ᵐ[μ] 0
h't : ∀ᵐ (x : α) ∂μ, f x ∈ t
d : Set E
d_count : Set.Countable d
hd : t ⊆ closure d
this : Encodable ↑d
s : ↑d → E →L[𝕜] 𝕜
hs : ∀ (x : ↑d), ‖s x‖ ≤ 1 ∧ (s x) ↑x = ↑‖↑x‖
A : ∀ a ∈ t, (∀ (x : ↑d), (s x) a = 0) → a = 0
⊢ f =ᵐ[μ] 0

Next tactic:
have hfs : ∀ y : d, ∀ᵐ x ∂μ, ⟪f x, s y⟫ = (0 : 𝕜) := fun y => hf (s y)
theorem ae_eq_zero_of_forall_dual_of_isSeparable [NormedAddCommGroup E] [NormedSpace 𝕜 E]
    {t : Set E} (ht : TopologicalSpace.IsSeparable t) {f : α → E}
    (hf : ∀ c : Dual 𝕜 E, (fun x => ⟪f x, c⟫) =ᵐ[μ] 0) (h't : ∀ᵐ x ∂μ, f x ∈ t) : f =ᵐ[μ] 0 := by
  rcases ht with ⟨d, d_count, hd⟩
  haveI : Encodable d := d_count.toEncodable
  have : ∀ x : d, ∃ g : E →L[𝕜] 𝕜, ‖g‖ ≤ 1 ∧ g x = ‖(x : E)‖ :=
    fun x => exists_dual_vector'' 𝕜 (x : E)
  choose s hs using this
  have A : ∀ a : E, a ∈ t → (∀ x, ⟪a, s x⟫ = (0 : 𝕜)) → a = 0 := by
    intro a hat ha
    contrapose! ha
    have a_pos : 0 < ‖a‖ := by simp only [ha, norm_pos_iff, Ne.def, not_false_iff]
    have a_mem : a ∈ closure d := hd hat
    obtain ⟨x, hx⟩ : ∃ x : d, dist a x < ‖a‖ / 2 := by
      rcases Metric.mem_closure_iff.1 a_mem (‖a‖ / 2) (half_pos a_pos) with ⟨x, h'x, hx⟩
      exact ⟨⟨x, h'x⟩, hx⟩
    use x
    have I : ‖a‖ / 2 < ‖(x : E)‖ := by
      have : ‖a‖ ≤ ‖(x : E)‖ + ‖a - x‖ := norm_le_insert' _ _
      have : ‖a - x‖ < ‖a‖ / 2 := by rwa [dist_eq_norm] at hx
      linarith
    intro h
    apply lt_irrefl ‖s x x‖
    calc
      ‖s x x‖ = ‖s x (x - a)‖ := by simp only [h, sub_zero, ContinuousLinearMap.map_sub]
      _ ≤ 1 * ‖(x : E) - a‖ := (ContinuousLinearMap.le_of_op_norm_le _ (hs x).1 _)
      _ < ‖a‖ / 2 := by rw [one_mul]; rwa [dist_eq_norm'] at hx
      _ < ‖(x : E)‖ := I
      _ = ‖s x x‖ := by rw [(hs x).2, IsROrC.norm_coe_norm]
  have hfs : ∀ y : d, ∀ᵐ x ∂μ, ⟪f x, s y⟫ = (0 : 𝕜) := fun y => hf (s y)
  

Proof state:
case intro.intro
α : Type u_1
E : Type u_2
𝕜 : Type u_3
m : MeasurableSpace α
μ : Measure α
inst✝² : IsROrC 𝕜
inst✝¹ : NormedAddCommGroup E
inst✝ : NormedSpace 𝕜 E
t : Set E
f : α → E
hf : ∀ (c : Dual 𝕜 E), (fun x => c (f x)) =ᵐ[μ] 0
h't : ∀ᵐ (x : α) ∂μ, f x ∈ t
d : Set E
d_count : Set.Countable d
hd : t ⊆ closure d
this : Encodable ↑d
s : ↑d → E →L[𝕜] 𝕜
hs : ∀ (x : ↑d), ‖s x‖ ≤ 1 ∧ (s x) ↑x = ↑‖↑x‖
A : ∀ a ∈ t, (∀ (x : ↑d), (s x) a = 0) → a = 0
hfs : ∀ (y : ↑d), ∀ᵐ (x : α) ∂μ, (s y) (f x) = 0
⊢ f =ᵐ[μ] 0

Next tactic:
have hf' : ∀ᵐ x ∂μ, ∀ y : d, ⟪f x, s y⟫ = (0 : 𝕜) := by rwa [ae_all_iff]
theorem ae_eq_zero_of_forall_dual_of_isSeparable [NormedAddCommGroup E] [NormedSpace 𝕜 E]
    {t : Set E} (ht : TopologicalSpace.IsSeparable t) {f : α → E}
    (hf : ∀ c : Dual 𝕜 E, (fun x => ⟪f x, c⟫) =ᵐ[μ] 0) (h't : ∀ᵐ x ∂μ, f x ∈ t) : f =ᵐ[μ] 0 := by
  rcases ht with ⟨d, d_count, hd⟩
  haveI : Encodable d := d_count.toEncodable
  have : ∀ x : d, ∃ g : E →L[𝕜] 𝕜, ‖g‖ ≤ 1 ∧ g x = ‖(x : E)‖ :=
    fun x => exists_dual_vector'' 𝕜 (x : E)
  choose s hs using this
  have A : ∀ a : E, a ∈ t → (∀ x, ⟪a, s x⟫ = (0 : 𝕜)) → a = 0 := by
    intro a hat ha
    contrapose! ha
    have a_pos : 0 < ‖a‖ := by simp only [ha, norm_pos_iff, Ne.def, not_false_iff]
    have a_mem : a ∈ closure d := hd hat
    obtain ⟨x, hx⟩ : ∃ x : d, dist a x < ‖a‖ / 2 := by
      rcases Metric.mem_closure_iff.1 a_mem (‖a‖ / 2) (half_pos a_pos) with ⟨x, h'x, hx⟩
      exact ⟨⟨x, h'x⟩, hx⟩
    use x
    have I : ‖a‖ / 2 < ‖(x : E)‖ := by
      have : ‖a‖ ≤ ‖(x : E)‖ + ‖a - x‖ := norm_le_insert' _ _
      have : ‖a - x‖ < ‖a‖ / 2 := by rwa [dist_eq_norm] at hx
      linarith
    intro h
    apply lt_irrefl ‖s x x‖
    calc
      ‖s x x‖ = ‖s x (x - a)‖ := by simp only [h, sub_zero, ContinuousLinearMap.map_sub]
      _ ≤ 1 * ‖(x : E) - a‖ := (ContinuousLinearMap.le_of_op_norm_le _ (hs x).1 _)
      _ < ‖a‖ / 2 := by rw [one_mul]; rwa [dist_eq_norm'] at hx
      _ < ‖(x : E)‖ := I
      _ = ‖s x x‖ := by rw [(hs x).2, IsROrC.norm_coe_norm]
  have hfs : ∀ y : d, ∀ᵐ x ∂μ, ⟪f x, s y⟫ = (0 : 𝕜) := fun y => hf (s y)
  have hf' : ∀ᵐ x ∂μ, ∀ y : d, ⟪f x, s y⟫ = (0 : 𝕜) := by 

Proof state:
α : Type u_1
E : Type u_2
𝕜 : Type u_3
m : MeasurableSpace α
μ : Measure α
inst✝² : IsROrC 𝕜
inst✝¹ : NormedAddCommGroup E
inst✝ : NormedSpace 𝕜 E
t : Set E
f : α → E
hf : ∀ (c : Dual 𝕜 E), (fun x => c (f x)) =ᵐ[μ] 0
h't : ∀ᵐ (x : α) ∂μ, f x ∈ t
d : Set E
d_count : Set.Countable d
hd : t ⊆ closure d
this : Encodable ↑d
s : ↑d → E →L[𝕜] 𝕜
hs : ∀ (x : ↑d), ‖s x‖ ≤ 1 ∧ (s x) ↑x = ↑‖↑x‖
A : ∀ a ∈ t, (∀ (x : ↑d), (s x) a = 0) → a = 0
hfs : ∀ (y : ↑d), ∀ᵐ (x : α) ∂μ, (s y) (f x) = 0
⊢ ∀ᵐ (x : α) ∂μ, ∀ (y : ↑d), (s y) (f x) = 0

Next tactic:
rwa [ae_all_iff]
theorem ae_eq_zero_of_forall_dual_of_isSeparable [NormedAddCommGroup E] [NormedSpace 𝕜 E]
    {t : Set E} (ht : TopologicalSpace.IsSeparable t) {f : α → E}
    (hf : ∀ c : Dual 𝕜 E, (fun x => ⟪f x, c⟫) =ᵐ[μ] 0) (h't : ∀ᵐ x ∂μ, f x ∈ t) : f =ᵐ[μ] 0 := by
  rcases ht with ⟨d, d_count, hd⟩
  haveI : Encodable d := d_count.toEncodable
  have : ∀ x : d, ∃ g : E →L[𝕜] 𝕜, ‖g‖ ≤ 1 ∧ g x = ‖(x : E)‖ :=
    fun x => exists_dual_vector'' 𝕜 (x : E)
  choose s hs using this
  have A : ∀ a : E, a ∈ t → (∀ x, ⟪a, s x⟫ = (0 : 𝕜)) → a = 0 := by
    intro a hat ha
    contrapose! ha
    have a_pos : 0 < ‖a‖ := by simp only [ha, norm_pos_iff, Ne.def, not_false_iff]
    have a_mem : a ∈ closure d := hd hat
    obtain ⟨x, hx⟩ : ∃ x : d, dist a x < ‖a‖ / 2 := by
      rcases Metric.mem_closure_iff.1 a_mem (‖a‖ / 2) (half_pos a_pos) with ⟨x, h'x, hx⟩
      exact ⟨⟨x, h'x⟩, hx⟩
    use x
    have I : ‖a‖ / 2 < ‖(x : E)‖ := by
      have : ‖a‖ ≤ ‖(x : E)‖ + ‖a - x‖ := norm_le_insert' _ _
      have : ‖a - x‖ < ‖a‖ / 2 := by rwa [dist_eq_norm] at hx
      linarith
    intro h
    apply lt_irrefl ‖s x x‖
    calc
      ‖s x x‖ = ‖s x (x - a)‖ := by simp only [h, sub_zero, ContinuousLinearMap.map_sub]
      _ ≤ 1 * ‖(x : E) - a‖ := (ContinuousLinearMap.le_of_op_norm_le _ (hs x).1 _)
      _ < ‖a‖ / 2 := by rw [one_mul]; rwa [dist_eq_norm'] at hx
      _ < ‖(x : E)‖ := I
      _ = ‖s x x‖ := by rw [(hs x).2, IsROrC.norm_coe_norm]
  have hfs : ∀ y : d, ∀ᵐ x ∂μ, ⟪f x, s y⟫ = (0 : 𝕜) := fun y => hf (s y)
  have hf' : ∀ᵐ x ∂μ, ∀ y : d, ⟪f x, s y⟫ = (0 : 𝕜) := by rwa [ae_all_iff]
  

Proof state:
case intro.intro
α : Type u_1
E : Type u_2
𝕜 : Type u_3
m : MeasurableSpace α
μ : Measure α
inst✝² : IsROrC 𝕜
inst✝¹ : NormedAddCommGroup E
inst✝ : NormedSpace 𝕜 E
t : Set E
f : α → E
hf : ∀ (c : Dual 𝕜 E), (fun x => c (f x)) =ᵐ[μ] 0
h't : ∀ᵐ (x : α) ∂μ, f x ∈ t
d : Set E
d_count : Set.Countable d
hd : t ⊆ closure d
this : Encodable ↑d
s : ↑d → E →L[𝕜] 𝕜
hs : ∀ (x : ↑d), ‖s x‖ ≤ 1 ∧ (s x) ↑x = ↑‖↑x‖
A : ∀ a ∈ t, (∀ (x : ↑d), (s x) a = 0) → a = 0
hfs : ∀ (y : ↑d), ∀ᵐ (x : α) ∂μ, (s y) (f x) = 0
hf' : ∀ᵐ (x : α) ∂μ, ∀ (y : ↑d), (s y) (f x) = 0
⊢ f =ᵐ[μ] 0

Next tactic:
filter_upwards [hf', h't] with x hx h'x
theorem ae_eq_zero_of_forall_dual_of_isSeparable [NormedAddCommGroup E] [NormedSpace 𝕜 E]
    {t : Set E} (ht : TopologicalSpace.IsSeparable t) {f : α → E}
    (hf : ∀ c : Dual 𝕜 E, (fun x => ⟪f x, c⟫) =ᵐ[μ] 0) (h't : ∀ᵐ x ∂μ, f x ∈ t) : f =ᵐ[μ] 0 := by
  rcases ht with ⟨d, d_count, hd⟩
  haveI : Encodable d := d_count.toEncodable
  have : ∀ x : d, ∃ g : E →L[𝕜] 𝕜, ‖g‖ ≤ 1 ∧ g x = ‖(x : E)‖ :=
    fun x => exists_dual_vector'' 𝕜 (x : E)
  choose s hs using this
  have A : ∀ a : E, a ∈ t → (∀ x, ⟪a, s x⟫ = (0 : 𝕜)) → a = 0 := by
    intro a hat ha
    contrapose! ha
    have a_pos : 0 < ‖a‖ := by simp only [ha, norm_pos_iff, Ne.def, not_false_iff]
    have a_mem : a ∈ closure d := hd hat
    obtain ⟨x, hx⟩ : ∃ x : d, dist a x < ‖a‖ / 2 := by
      rcases Metric.mem_closure_iff.1 a_mem (‖a‖ / 2) (half_pos a_pos) with ⟨x, h'x, hx⟩
      exact ⟨⟨x, h'x⟩, hx⟩
    use x
    have I : ‖a‖ / 2 < ‖(x : E)‖ := by
      have : ‖a‖ ≤ ‖(x : E)‖ + ‖a - x‖ := norm_le_insert' _ _
      have : ‖a - x‖ < ‖a‖ / 2 := by rwa [dist_eq_norm] at hx
      linarith
    intro h
    apply lt_irrefl ‖s x x‖
    calc
      ‖s x x‖ = ‖s x (x - a)‖ := by simp only [h, sub_zero, ContinuousLinearMap.map_sub]
      _ ≤ 1 * ‖(x : E) - a‖ := (ContinuousLinearMap.le_of_op_norm_le _ (hs x).1 _)
      _ < ‖a‖ / 2 := by rw [one_mul]; rwa [dist_eq_norm'] at hx
      _ < ‖(x : E)‖ := I
      _ = ‖s x x‖ := by rw [(hs x).2, IsROrC.norm_coe_norm]
  have hfs : ∀ y : d, ∀ᵐ x ∂μ, ⟪f x, s y⟫ = (0 : 𝕜) := fun y => hf (s y)
  have hf' : ∀ᵐ x ∂μ, ∀ y : d, ⟪f x, s y⟫ = (0 : 𝕜) := by rwa [ae_all_iff]
  filter_upwards [hf', h't] with x hx h'x
  

Proof state:
case h
α : Type u_1
E : Type u_2
𝕜 : Type u_3
m : MeasurableSpace α
μ : Measure α
inst✝² : IsROrC 𝕜
inst✝¹ : NormedAddCommGroup E
inst✝ : NormedSpace 𝕜 E
t : Set E
f : α → E
hf : ∀ (c : Dual 𝕜 E), (fun x => c (f x)) =ᵐ[μ] 0
h't : ∀ᵐ (x : α) ∂μ, f x ∈ t
d : Set E
d_count : Set.Countable d
hd : t ⊆ closure d
this : Encodable ↑d
s : ↑d → E →L[𝕜] 𝕜
hs : ∀ (x : ↑d), ‖s x‖ ≤ 1 ∧ (s x) ↑x = ↑‖↑x‖
A : ∀ a ∈ t, (∀ (x : ↑d), (s x) a = 0) → a = 0
hfs : ∀ (y : ↑d), ∀ᵐ (x : α) ∂μ, (s y) (f x) = 0
hf' : ∀ᵐ (x : α) ∂μ, ∀ (y : ↑d), (s y) (f x) = 0
x : α
hx : ∀ (y : ↑d), (s y) (f x) = 0
h'x : f x ∈ t
⊢ f x = OfNat.ofNat 0 x

Next tactic:
exact A (f x) h'x hx
theorem ae_const_le_iff_forall_lt_measure_zero {β} [LinearOrder β] [TopologicalSpace β]
    [OrderTopology β] [FirstCountableTopology β] (f : α → β) (c : β) :
    (∀ᵐ x ∂μ, c ≤ f x) ↔ ∀ b < c, μ {x | f x ≤ b} = 0 := by
  

Proof state:
α : Type u_1
E : Type u_2
m m0 : MeasurableSpace α
μ : Measure α
s t : Set α
inst✝⁶ : NormedAddCommGroup E
inst✝⁵ : NormedSpace ℝ E
inst✝⁴ : CompleteSpace E
p : ℝ≥0∞
β : Type u_3
inst✝³ : LinearOrder β
inst✝² : TopologicalSpace β
inst✝¹ : OrderTopology β
inst✝ : FirstCountableTopology β
f : α → β
c : β
⊢ (∀ᵐ (x : α) ∂μ, c ≤ f x) ↔ ∀ b < c, ↑↑μ {x | f x ≤ b} = 0

Next tactic:
rw [ae_iff]
theorem ae_const_le_iff_forall_lt_measure_zero {β} [LinearOrder β] [TopologicalSpace β]
    [OrderTopology β] [FirstCountableTopology β] (f : α → β) (c : β) :
    (∀ᵐ x ∂μ, c ≤ f x) ↔ ∀ b < c, μ {x | f x ≤ b} = 0 := by
  rw [ae_iff]
  

Proof state:
α : Type u_1
E : Type u_2
m m0 : MeasurableSpace α
μ : Measure α
s t : Set α
inst✝⁶ : NormedAddCommGroup E
inst✝⁵ : NormedSpace ℝ E
inst✝⁴ : CompleteSpace E
p : ℝ≥0∞
β : Type u_3
inst✝³ : LinearOrder β
inst✝² : TopologicalSpace β
inst✝¹ : OrderTopology β
inst✝ : FirstCountableTopology β
f : α → β
c : β
⊢ ↑↑μ {a | ¬c ≤ f a} = 0 ↔ ∀ b < c, ↑↑μ {x | f x ≤ b} = 0

Next tactic:
push_neg
theorem ae_const_le_iff_forall_lt_measure_zero {β} [LinearOrder β] [TopologicalSpace β]
    [OrderTopology β] [FirstCountableTopology β] (f : α → β) (c : β) :
    (∀ᵐ x ∂μ, c ≤ f x) ↔ ∀ b < c, μ {x | f x ≤ b} = 0 := by
  rw [ae_iff]
  push_neg
  

Proof state:
α : Type u_1
E : Type u_2
m m0 : MeasurableSpace α
μ : Measure α
s t : Set α
inst✝⁶ : NormedAddCommGroup E
inst✝⁵ : NormedSpace ℝ E
inst✝⁴ : CompleteSpace E
p : ℝ≥0∞
β : Type u_3
inst✝³ : LinearOrder β
inst✝² : TopologicalSpace β
inst✝¹ : OrderTopology β
inst✝ : FirstCountableTopology β
f : α → β
c : β
⊢ ↑↑μ {a | f a < c} = 0 ↔ ∀ b < c, ↑↑μ {x | f x ≤ b} = 0

Next tactic:
constructor