Theorem: continuousOn_iff'
File: Mathlib/Topology/ContinuousOn.lean

tactic: rw [continuousOn_iff_continuous_restrict, continuous_def]
state_before: α : Type u_1
β : Type u_2
γ : Type u_3
δ : Type u_4
inst✝⁴ : TopologicalSpace α
ι : Type u_5
π : ι → Type u_6
inst✝³ : (i : ι) → TopologicalSpace (π i)
inst✝² : TopologicalSpace β
inst✝¹ : TopologicalSpace γ
inst✝ : TopologicalSpace δ
f : α → β
s : Set α
this : ∀ (t : Set β), IsOpen (s.restrict f ⁻¹' t) ↔ ∃ u, IsOpen u ∧ f ⁻¹' t ∩ s = u ∩ s
⊢ ContinuousOn f s ↔ ∀ (t : Set β), IsOpen t → ∃ u, IsOpen u ∧ f ⁻¹' t ∩ s = u ∩ s
state_after: α : Type u_1
β : Type u_2
γ : Type u_3
δ : Type u_4
inst✝⁴ : TopologicalSpace α
ι : Type u_5
π : ι → Type u_6
inst✝³ : (i : ι) → TopologicalSpace (π i)
inst✝² : TopologicalSpace β
inst✝¹ : TopologicalSpace γ
inst✝ : TopologicalSpace δ
f : α → β
s : Set α
this : ∀ (t : Set β), IsOpen (s.restrict f ⁻¹' t) ↔ ∃ u, IsOpen u ∧ f ⁻¹' t ∩ s = u ∩ s
⊢ (∀ (s_1 : Set β), IsOpen s_1 → IsOpen (s.restrict f ⁻¹' s_1)) ↔
    ∀ (t : Set β), IsOpen t → ∃ u, IsOpen u ∧ f ⁻¹' t ∩ s = u ∩ s

tactic: simp only [this]
state_before: α : Type u_1
β : Type u_2
γ : Type u_3
δ : Type u_4
inst✝⁴ : TopologicalSpace α
ι : Type u_5
π : ι → Type u_6
inst✝³ : (i : ι) → TopologicalSpace (π i)
inst✝² : TopologicalSpace β
inst✝¹ : TopologicalSpace γ
inst✝ : TopologicalSpace δ
f : α → β
s : Set α
this : ∀ (t : Set β), IsOpen (s.restrict f ⁻¹' t) ↔ ∃ u, IsOpen u ∧ f ⁻¹' t ∩ s = u ∩ s
⊢ (∀ (s_1 : Set β), IsOpen s_1 → IsOpen (s.restrict f ⁻¹' s_1)) ↔
    ∀ (t : Set β), IsOpen t → ∃ u, IsOpen u ∧ f ⁻¹' t ∩ s = u ∩ s
state_after: no goals

tactic: intro t
state_before: α : Type u_1
β : Type u_2
γ : Type u_3
δ : Type u_4
inst✝⁴ : TopologicalSpace α
ι : Type u_5
π : ι → Type u_6
inst✝³ : (i : ι) → TopologicalSpace (π i)
inst✝² : TopologicalSpace β
inst✝¹ : TopologicalSpace γ
inst✝ : TopologicalSpace δ
f : α → β
s : Set α
⊢ ∀ (t : Set β), IsOpen (s.restrict f ⁻¹' t) ↔ ∃ u, IsOpen u ∧ f ⁻¹' t ∩ s = u ∩ s
state_after: α : Type u_1
β : Type u_2
γ : Type u_3
δ : Type u_4
inst✝⁴ : TopologicalSpace α
ι : Type u_5
π : ι → Type u_6
inst✝³ : (i : ι) → TopologicalSpace (π i)
inst✝² : TopologicalSpace β
inst✝¹ : TopologicalSpace γ
inst✝ : TopologicalSpace δ
f : α → β
s : Set α
t : Set β
⊢ IsOpen (s.restrict f ⁻¹' t) ↔ ∃ u, IsOpen u ∧ f ⁻¹' t ∩ s = u ∩ s

tactic: rw [isOpen_induced_iff, Set.restrict_eq, Set.preimage_comp]
state_before: α : Type u_1
β : Type u_2
γ : Type u_3
δ : Type u_4
inst✝⁴ : TopologicalSpace α
ι : Type u_5
π : ι → Type u_6
inst✝³ : (i : ι) → TopologicalSpace (π i)
inst✝² : TopologicalSpace β
inst✝¹ : TopologicalSpace γ
inst✝ : TopologicalSpace δ
f : α → β
s : Set α
t : Set β
⊢ IsOpen (s.restrict f ⁻¹' t) ↔ ∃ u, IsOpen u ∧ f ⁻¹' t ∩ s = u ∩ s
state_after: α : Type u_1
β : Type u_2
γ : Type u_3
δ : Type u_4
inst✝⁴ : TopologicalSpace α
ι : Type u_5
π : ι → Type u_6
inst✝³ : (i : ι) → TopologicalSpace (π i)
inst✝² : TopologicalSpace β
inst✝¹ : TopologicalSpace γ
inst✝ : TopologicalSpace δ
f : α → β
s : Set α
t : Set β
⊢ (∃ t_1, IsOpen t_1 ∧ Subtype.val ⁻¹' t_1 = Subtype.val ⁻¹' (f ⁻¹' t)) ↔ ∃ u, IsOpen u ∧ f ⁻¹' t ∩ s = u ∩ s

tactic: simp only [Subtype.preimage_coe_eq_preimage_coe_iff]
state_before: α : Type u_1
β : Type u_2
γ : Type u_3
δ : Type u_4
inst✝⁴ : TopologicalSpace α
ι : Type u_5
π : ι → Type u_6
inst✝³ : (i : ι) → TopologicalSpace (π i)
inst✝² : TopologicalSpace β
inst✝¹ : TopologicalSpace γ
inst✝ : TopologicalSpace δ
f : α → β
s : Set α
t : Set β
⊢ (∃ t_1, IsOpen t_1 ∧ Subtype.val ⁻¹' t_1 = Subtype.val ⁻¹' (f ⁻¹' t)) ↔ ∃ u, IsOpen u ∧ f ⁻¹' t ∩ s = u ∩ s
state_after: α : Type u_1
β : Type u_2
γ : Type u_3
δ : Type u_4
inst✝⁴ : TopologicalSpace α
ι : Type u_5
π : ι → Type u_6
inst✝³ : (i : ι) → TopologicalSpace (π i)
inst✝² : TopologicalSpace β
inst✝¹ : TopologicalSpace γ
inst✝ : TopologicalSpace δ
f : α → β
s : Set α
t : Set β
⊢ (∃ t_1, IsOpen t_1 ∧ s ∩ t_1 = s ∩ f ⁻¹' t) ↔ ∃ u, IsOpen u ∧ f ⁻¹' t ∩ s = u ∩ s

tactic: rintro ⟨u, ou, useq⟩
state_before: case mpr
α : Type u_1
β : Type u_2
γ : Type u_3
δ : Type u_4
inst✝⁴ : TopologicalSpace α
ι : Type u_5
π : ι → Type u_6
inst✝³ : (i : ι) → TopologicalSpace (π i)
inst✝² : TopologicalSpace β
inst✝¹ : TopologicalSpace γ
inst✝ : TopologicalSpace δ
f : α → β
s : Set α
t : Set β
⊢ (∃ u, IsOpen u ∧ f ⁻¹' t ∩ s = u ∩ s) → ∃ t_1, IsOpen t_1 ∧ s ∩ t_1 = s ∩ f ⁻¹' t
state_after: case mpr.intro.intro
α : Type u_1
β : Type u_2
γ : Type u_3
δ : Type u_4
inst✝⁴ : TopologicalSpace α
ι : Type u_5
π : ι → Type u_6
inst✝³ : (i : ι) → TopologicalSpace (π i)
inst✝² : TopologicalSpace β
inst✝¹ : TopologicalSpace γ
inst✝ : TopologicalSpace δ
f : α → β
s : Set α
t : Set β
u : Set α
ou : IsOpen u
useq : f ⁻¹' t ∩ s = u ∩ s
⊢ ∃ t_1, IsOpen t_1 ∧ s ∩ t_1 = s ∩ f ⁻¹' t

tactic: exact ⟨u, ou, by simpa only [Set.inter_comm, eq_comm] using useq⟩
state_before: case mpr.intro.intro
α : Type u_1
β : Type u_2
γ : Type u_3
δ : Type u_4
inst✝⁴ : TopologicalSpace α
ι : Type u_5
π : ι → Type u_6
inst✝³ : (i : ι) → TopologicalSpace (π i)
inst✝² : TopologicalSpace β
inst✝¹ : TopologicalSpace γ
inst✝ : TopologicalSpace δ
f : α → β
s : Set α
t : Set β
u : Set α
ou : IsOpen u
useq : f ⁻¹' t ∩ s = u ∩ s
⊢ ∃ t_1, IsOpen t_1 ∧ s ∩ t_1 = s ∩ f ⁻¹' t
state_after: no goals

tactic: simpa only [Set.inter_comm, eq_comm] using useq
state_before: α : Type u_1
β : Type u_2
γ : Type u_3
δ : Type u_4
inst✝⁴ : TopologicalSpace α
ι : Type u_5
π : ι → Type u_6
inst✝³ : (i : ι) → TopologicalSpace (π i)
inst✝² : TopologicalSpace β
inst✝¹ : TopologicalSpace γ
inst✝ : TopologicalSpace δ
f : α → β
s : Set α
t : Set β
u : Set α
ou : IsOpen u
useq : f ⁻¹' t ∩ s = u ∩ s
⊢ s ∩ u = s ∩ f ⁻¹' t
state_after: no goals