case refine'_1
X : Type u_1
inst✝ : TopologicalSpace X
s : Set (OnePoint X)
t : Set X
⊢ ∀ (i : Set (OnePoint X)), ∞ ∈ i ∧ IsOpen i → ∃ i', (IsClosed i' ∧ IsCompact i') ∧ some '' i'ᶜ ⊆ i ∩ {∞}ᶜ

case refine'_2
X : Type u_1
inst✝ : TopologicalSpace X
s : Set (OnePoint X)
t : Set X
⊢ ∀ (i' : Set X), IsClosed i' ∧ IsCompact i' → ∃ i, (∞ ∈ i ∧ IsOpen i) ∧ i ∩ {∞}ᶜ ⊆ some '' i'ᶜ
X : Type u_1
inst✝ : TopologicalSpace X
s : Set (OnePoint X)
t : Set X
⊢ 𝓝[{∞}ᶜ] ∞ = map some (coclosedCompact X)
refine' (nhdsWithin_basis_open ∞ _).ext (hasBasis_coclosedCompact.map _) _ _
case refine'_1.intro
X : Type u_1
inst✝ : TopologicalSpace X
s✝ : Set (OnePoint X)
t : Set X
s : Set (OnePoint X)
hs : ∞ ∈ s
hso : IsOpen s
⊢ ∃ i', (IsClosed i' ∧ IsCompact i') ∧ some '' i'ᶜ ⊆ s ∩ {∞}ᶜ
case refine'_1
X : Type u_1
inst✝ : TopologicalSpace X
s : Set (OnePoint X)
t : Set X
⊢ ∀ (i : Set (OnePoint X)), ∞ ∈ i ∧ IsOpen i → ∃ i', (IsClosed i' ∧ IsCompact i') ∧ some '' i'ᶜ ⊆ i ∩ {∞}ᶜ
rintro s ⟨hs, hso⟩
case refine'_1.intro
X : Type u_1
inst✝ : TopologicalSpace X
s✝ : Set (OnePoint X)
t : Set X
s : Set (OnePoint X)
hs : ∞ ∈ s
hso : IsOpen s
⊢ some '' (some ⁻¹' s)ᶜᶜ ⊆ s ∩ {∞}ᶜ
case refine'_1.intro
X : Type u_1
inst✝ : TopologicalSpace X
s✝ : Set (OnePoint X)
t : Set X
s : Set (OnePoint X)
hs : ∞ ∈ s
hso : IsOpen s
⊢ ∃ i', (IsClosed i' ∧ IsCompact i') ∧ some '' i'ᶜ ⊆ s ∩ {∞}ᶜ
refine' ⟨_, (isOpen_iff_of_mem hs).mp hso, _⟩
no goals
case refine'_1.intro
X : Type u_1
inst✝ : TopologicalSpace X
s✝ : Set (OnePoint X)
t : Set X
s : Set (OnePoint X)
hs : ∞ ∈ s
hso : IsOpen s
⊢ some '' (some ⁻¹' s)ᶜᶜ ⊆ s ∩ {∞}ᶜ
simp [Subset.rfl]
case refine'_2.intro
X : Type u_1
inst✝ : TopologicalSpace X
s✝ : Set (OnePoint X)
t s : Set X
h₁ : IsClosed s
h₂ : IsCompact s
⊢ ∃ i, (∞ ∈ i ∧ IsOpen i) ∧ i ∩ {∞}ᶜ ⊆ some '' sᶜ
case refine'_2
X : Type u_1
inst✝ : TopologicalSpace X
s : Set (OnePoint X)
t : Set X
⊢ ∀ (i' : Set X), IsClosed i' ∧ IsCompact i' → ∃ i, (∞ ∈ i ∧ IsOpen i) ∧ i ∩ {∞}ᶜ ⊆ some '' i'ᶜ
rintro s ⟨h₁, h₂⟩
case refine'_2.intro
X : Type u_1
inst✝ : TopologicalSpace X
s✝ : Set (OnePoint X)
t s : Set X
h₁ : IsClosed s
h₂ : IsCompact s
⊢ (some '' s)ᶜ ∩ {∞}ᶜ ⊆ some '' sᶜ
case refine'_2.intro
X : Type u_1
inst✝ : TopologicalSpace X
s✝ : Set (OnePoint X)
t s : Set X
h₁ : IsClosed s
h₂ : IsCompact s
⊢ ∃ i, (∞ ∈ i ∧ IsOpen i) ∧ i ∩ {∞}ᶜ ⊆ some '' sᶜ
refine' ⟨_, ⟨mem_compl infty_not_mem_image_coe, isOpen_compl_image_coe.2 ⟨h₁, h₂⟩⟩, _⟩
no goals
case refine'_2.intro
X : Type u_1
inst✝ : TopologicalSpace X
s✝ : Set (OnePoint X)
t s : Set X
h₁ : IsClosed s
h₂ : IsCompact s
⊢ (some '' s)ᶜ ∩ {∞}ᶜ ⊆ some '' sᶜ
simp [compl_image_coe, ← diff_eq, subset_preimage_image]