case intro
α : Type u_1
β : Type u_2
γ : Type ?u.346278
δ : Type ?u.346281
inst✝³ : TopologicalSpace α
inst✝² : TopologicalSpace β
inst✝¹ : TopologicalSpace γ
inst✝ : TopologicalSpace δ
f : α → β
s : Set α
t : Set β
hf : ContinuousOn f s
hs : IsClosed s
ht : IsClosed t
u : Set α
hu : IsClosed u ∧ f ⁻¹' t ∩ s = u ∩ s
⊢ IsClosed (s ∩ f ⁻¹' t)
α : Type u_1
β : Type u_2
γ : Type ?u.346278
δ : Type ?u.346281
inst✝³ : TopologicalSpace α
inst✝² : TopologicalSpace β
inst✝¹ : TopologicalSpace γ
inst✝ : TopologicalSpace δ
f : α → β
s : Set α
t : Set β
hf : ContinuousOn f s
hs : IsClosed s
ht : IsClosed t
⊢ IsClosed (s ∩ f ⁻¹' t)
rcases continuousOn_iff_isClosed.1 hf t ht with ⟨u, hu⟩
case intro
α : Type u_1
β : Type u_2
γ : Type ?u.346278
δ : Type ?u.346281
inst✝³ : TopologicalSpace α
inst✝² : TopologicalSpace β
inst✝¹ : TopologicalSpace γ
inst✝ : TopologicalSpace δ
f : α → β
s : Set α
t : Set β
hf : ContinuousOn f s
hs : IsClosed s
ht : IsClosed t
u : Set α
hu : IsClosed u ∧ f ⁻¹' t ∩ s = u ∩ s
⊢ IsClosed (u ∩ s)
case intro
α : Type u_1
β : Type u_2
γ : Type ?u.346278
δ : Type ?u.346281
inst✝³ : TopologicalSpace α
inst✝² : TopologicalSpace β
inst✝¹ : TopologicalSpace γ
inst✝ : TopologicalSpace δ
f : α → β
s : Set α
t : Set β
hf : ContinuousOn f s
hs : IsClosed s
ht : IsClosed t
u : Set α
hu : IsClosed u ∧ f ⁻¹' t ∩ s = u ∩ s
⊢ IsClosed (s ∩ f ⁻¹' t)
rw [inter_comm, hu.2]
no goals
case intro
α : Type u_1
β : Type u_2
γ : Type ?u.346278
δ : Type ?u.346281
inst✝³ : TopologicalSpace α
inst✝² : TopologicalSpace β
inst✝¹ : TopologicalSpace γ
inst✝ : TopologicalSpace δ
f : α → β
s : Set α
t : Set β
hf : ContinuousOn f s
hs : IsClosed s
ht : IsClosed t
u : Set α
hu : IsClosed u ∧ f ⁻¹' t ∩ s = u ∩ s
⊢ IsClosed (u ∩ s)
apply IsClosed.inter hu.1 hs