mathlib-initiative/mathlib-tactics huggingface dataset:
Module: Mathlib.Topology.Connected.Basic

Goal state before:
pp: α : Type u
inst✝ : TopologicalSpace α
s : Set α
h :
  ∀ (t t' : Set α),
    IsClosed[inst✝] t → IsClosed[inst✝] t' → s ⊆ t ∪ t' → (s ∩ t).Nonempty → (s ∩ t').Nonempty → (s ∩ (t ∩ t')).Nonempty
u v : Set α
hu : IsOpen[inst✝] u
hv : IsOpen[inst✝] v
huv : s ⊆ u ∪ v
x : α
xs : x ∈ s
xu : x ∈ u
y : α
ys : y ∈ s
yv : y ∈ v
⊢ ¬s ⊆ uᶜ ∪ vᶜ

Tactic:
]

Goal state after:
α : Type u
inst✝ : TopologicalSpace α
s : Set α
h :
  ∀ (t t' : Set α),
    IsClosed[inst✝] t → IsClosed[inst✝] t' → s ⊆ t ∪ t' → (s ∩ t).Nonempty → (s ∩ t').Nonempty → (s ∩ (t ∩ t')).Nonempty
u v : Set α
hu : IsOpen[inst✝] u
hv : IsOpen[inst✝] v
huv : s ⊆ u ∪ v
x : α
xs : x ∈ s
xu : x ∈ u
y : α
ys : y ∈ s
yv : y ∈ v
⊢ ¬s ⊆ uᶜ ∪ vᶜ
Module: Mathlib.Topology.Compactness.Lindelof

Goal state before:
pp: X : Type u
inst✝¹ : TopologicalSpace X
s : Set X
hs : IsLindelof s
f : Filter X
inst✝ : CountableInterFilter f
hf : ∀ x ∈ s, ∃ t ∈ 𝓝[s] x, tᶜ ∈ f
x : X
hx : x ∈ s
⊢ ∃ i ∈ 𝓝 x ⊓ 𝓟 s, (id i)ᶜ ∈ f

Tactic:
]

Goal state after:
X : Type u
inst✝¹ : TopologicalSpace X
s : Set X
hs : IsLindelof s
f : Filter X
inst✝ : CountableInterFilter f
hf : ∀ x ∈ s, ∃ t ∈ 𝓝[s] x, tᶜ ∈ f
x : X
hx : x ∈ s
⊢ ∃ i ∈ 𝓝 x ⊓ 𝓟 s, (id i)ᶜ ∈ f
Module: Mathlib.Topology.Compactness.Lindelof

Goal state before:
pp: X : Type u
inst✝ : TopologicalSpace X
s : Set X
hs : IsLindelof s
p : Set X → Prop
hmono : ∀ ⦃s t : Set X⦄, s ⊆ t → p t → p s
hcountable_union : ∀ (S : Set (Set X)), S.Countable → (∀ s ∈ S, p s) → p (⋃₀ S)
hnhds : ∀ x ∈ s, ∃ t ∈ 𝓝[s] x, p t
f : Filter X := ofCountableUnion {t | p t} hcountable_union ⋯
this : sᶜ ∈ f
⊢ p sᶜᶜ

Tactic:
]

Goal state after:
X : Type u
inst✝ : TopologicalSpace X
s : Set X
hs : IsLindelof s
p : Set X → Prop
hmono : ∀ ⦃s t : Set X⦄, s ⊆ t → p t → p s
hcountable_union : ∀ (S : Set (Set X)), S.Countable → (∀ s ∈ S, p s) → p (⋃₀ S)
hnhds : ∀ x ∈ s, ∃ t ∈ 𝓝[s] x, p t
f : Filter X := ofCountableUnion {t | p t} hcountable_union ⋯
this : sᶜ ∈ f
⊢ p sᶜᶜ
Module: Mathlib.Topology.Connected.Basic

Goal state before:
pp: α : Type u
inst✝ : TopologicalSpace α
s : Set α
h :
  ∀ (t t' : Set α),
    IsClosed[inst✝] t → IsClosed[inst✝] t' → s ⊆ t ∪ t' → (s ∩ t).Nonempty → (s ∩ t').Nonempty → (s ∩ (t ∩ t')).Nonempty
u v : Set α
hu : IsOpen[inst✝] u
hv : IsOpen[inst✝] v
huv : s ⊆ u ∪ v
x : α
xs : x ∈ s
xu : x ∈ u
y : α
ys : y ∈ s
yv : y ∈ v
h' : s ⊆ uᶜ ∪ vᶜ
xv : x ∉ v
yu : y ∉ u
this : (s ∩ (u ∪ v)ᶜ).Nonempty
⊢ False

Tactic:
]

Goal state after:
α : Type u
inst✝ : TopologicalSpace α
s : Set α
h :
  ∀ (t t' : Set α),
    IsClosed[inst✝] t → IsClosed[inst✝] t' → s ⊆ t ∪ t' → (s ∩ t).Nonempty → (s ∩ t').Nonempty → (s ∩ (t ∩ t')).Nonempty
u v : Set α
hu : IsOpen[inst✝] u
hv : IsOpen[inst✝] v
huv : s ⊆ u ∪ v
x : α
xs : x ∈ s
xu : x ∈ u
y : α
ys : y ∈ s
yv : y ∈ v
h' : s ⊆ uᶜ ∪ vᶜ
xv : x ∉ v
yu : y ∉ u
this : (s ∩ (u ∪ v)ᶜ).Nonempty
⊢ False
Module: Mathlib.Topology.Compactness.Lindelof

Goal state before:
pp: X : Type u
inst✝¹ : TopologicalSpace X
s t : Set X
hs : IsLindelof s
ht : IsClosed[inst✝¹] t
f : Filter X
hnf : f.NeBot
inst✝ : CountableInterFilter f
hstf : f ≤ 𝓟 s ∧ f ≤ 𝓟 t
⊢ ∃ x ∈ s ∩ t, ClusterPt x f

Tactic:
]

Goal state after:
X : Type u
inst✝¹ : TopologicalSpace X
s t : Set X
hs : IsLindelof s
ht : IsClosed[inst✝¹] t
f : Filter X
hnf : f.NeBot
inst✝ : CountableInterFilter f
hstf : f ≤ 𝓟 s ∧ f ≤ 𝓟 t
⊢ ∃ x ∈ s ∩ t, ClusterPt x f
Module: Mathlib.Topology.Connected.Clopen

Goal state before:
pp: case h
α : Type u
inst✝ : TopologicalSpace α
s : Set α
hs : IsPreconnected s
P : α → α → Prop
h : ∀ x ∈ s, ∀ᶠ (y : α) in 𝓝[s] x, P x y ∧ P y x
h' : ∀ (x y z : α), x ∈ s → y ∈ s → z ∈ s → P x y → P y z → P x z
x✝ y : α
hx✝ : x✝ ∈ s
hy : y ∈ s
Q : ↑s → ↑s → Prop := fun a b ↦ P ↑a ↑b
this : PreconnectedSpace ↑s
x : α
hx : x ∈ s
Z✝ : ∀ᶠ (y : α) in 𝓝[s] x, P x y ∧ P y x
Z : ∀ᶠ (y : α) in Filter.map Subtype.val (𝓝 ⟨x, ?h✝⟩), P x y ∧ P y x
⊢ ∀ᶠ (y : { x // x ∈ s }) in 𝓝 ⟨x, hx⟩, Q ⟨x, hx⟩ y ∧ Q y ⟨x, hx⟩

pp: case h
α : Type u
inst✝ : TopologicalSpace α
s : Set α
hs : IsPreconnected s
P : α → α → Prop
h : ∀ x ∈ s, ∀ᶠ (y : α) in 𝓝[s] x, P x y ∧ P y x
h' : ∀ (x y z : α), x ∈ s → y ∈ s → z ∈ s → P x y → P y z → P x z
x✝ y : α
hx✝ : x✝ ∈ s
hy : y ∈ s
Q : ↑s → ↑s → Prop := fun a b ↦ P ↑a ↑b
this : PreconnectedSpace ↑s
x : α
hx : x ∈ s
Z : ∀ᶠ (y : α) in 𝓝[s] x, P x y ∧ P y x
⊢ x ∈ s

Tactic:
]

Goal state after:
case h
α : Type u
inst✝ : TopologicalSpace α
s : Set α
hs : IsPreconnected s
P : α → α → Prop
h : ∀ x ∈ s, ∀ᶠ (y : α) in 𝓝[s] x, P x y ∧ P y x
h' : ∀ (x y z : α), x ∈ s → y ∈ s → z ∈ s → P x y → P y z → P x z
x✝ y : α
hx✝ : x✝ ∈ s
hy : y ∈ s
Q : ↑s → ↑s → Prop := fun a b ↦ P ↑a ↑b
this : PreconnectedSpace ↑s
x : α
hx : x ∈ s
Z✝ : ∀ᶠ (y : α) in 𝓝[s] x, P x y ∧ P y x
Z : ∀ᶠ (y : α) in Filter.map Subtype.val (𝓝 ⟨x, ?h✝⟩), P x y ∧ P y x
⊢ ∀ᶠ (y : { x // x ∈ s }) in 𝓝 ⟨x, hx⟩, Q ⟨x, hx⟩ y ∧ Q y ⟨x, hx⟩

case h
α : Type u
inst✝ : TopologicalSpace α
s : Set α
hs : IsPreconnected s
P : α → α → Prop
h : ∀ x ∈ s, ∀ᶠ (y : α) in 𝓝[s] x, P x y ∧ P y x
h' : ∀ (x y z : α), x ∈ s → y ∈ s → z ∈ s → P x y → P y z → P x z
x✝ y : α
hx✝ : x✝ ∈ s
hy : y ∈ s
Q : ↑s → ↑s → Prop := fun a b ↦ P ↑a ↑b
this : PreconnectedSpace ↑s
x : α
hx : x ∈ s
Z : ∀ᶠ (y : α) in 𝓝[s] x, P x y ∧ P y x
⊢ x ∈ s
Module: Mathlib.Topology.Connected.Basic

Goal state before:
pp: α : Type u
β : Type v
inst✝¹ : TopologicalSpace α
inst✝ : TopologicalSpace β
s : Set α
f : α → β
hf : IsInducing f
h : IsPreconnected (f '' s)
x : α
hxs : x ∈ s
y : α
hys : y ∈ s
u : Set β
hu : IsOpen[inst✝] u
hu' : IsOpen[inst✝¹] (f ⁻¹' u)
hxu : x ∈ f ⁻¹' u
v : Set β
hv : IsOpen[inst✝] v
hv' : IsOpen[inst✝¹] (f ⁻¹' v)
hyv : y ∈ f ⁻¹' v
huv : s ⊆ f ⁻¹' u ∪ f ⁻¹' v
⊢ s ⊆ f ⁻¹' (u ∪ v)

Tactic:
]

Goal state after:
α : Type u
β : Type v
inst✝¹ : TopologicalSpace α
inst✝ : TopologicalSpace β
s : Set α
f : α → β
hf : IsInducing f
h : IsPreconnected (f '' s)
x : α
hxs : x ∈ s
y : α
hys : y ∈ s
u : Set β
hu : IsOpen[inst✝] u
hu' : IsOpen[inst✝¹] (f ⁻¹' u)
hxu : x ∈ f ⁻¹' u
v : Set β
hv : IsOpen[inst✝] v
hv' : IsOpen[inst✝¹] (f ⁻¹' v)
hyv : y ∈ f ⁻¹' v
huv : s ⊆ f ⁻¹' u ∪ f ⁻¹' v
⊢ s ⊆ f ⁻¹' (u ∪ v)
Module: Mathlib.Topology.Compactness.Lindelof

Goal state before:
pp: X : Type u
Y : Type v
inst✝² : TopologicalSpace X
inst✝¹ : TopologicalSpace Y
s : Set X
f : X → Y
hs : IsLindelof s
hf : ContinuousOn f s
l : Filter Y
lne : l.NeBot
inst✝ : CountableInterFilter l
ls : l ≤ 𝓟 (f '' s)
this✝ : (comap f l ⊓ 𝓟 s).NeBot
x : X
hxs : x ∈ s
hx : ClusterPt x (comap f l ⊓ 𝓟 s)
this : (𝓝 x ⊓ (comap f l ⊓ 𝓟 s)).NeBot
⊢ 𝓝 x ⊓ (comap f l ⊓ 𝓟 s) = 𝓝 x ⊓ 𝓟 s ⊓ comap f l

Tactic:
]

Goal state after:
X : Type u
Y : Type v
inst✝² : TopologicalSpace X
inst✝¹ : TopologicalSpace Y
s : Set X
f : X → Y
hs : IsLindelof s
hf : ContinuousOn f s
l : Filter Y
lne : l.NeBot
inst✝ : CountableInterFilter l
ls : l ≤ 𝓟 (f '' s)
this✝ : (comap f l ⊓ 𝓟 s).NeBot
x : X
hxs : x ∈ s
hx : ClusterPt x (comap f l ⊓ 𝓟 s)
this : (𝓝 x ⊓ (comap f l ⊓ 𝓟 s)).NeBot
⊢ 𝓝 x ⊓ (comap f l ⊓ 𝓟 s) = 𝓝 x ⊓ 𝓟 s ⊓ comap f l
Module: Mathlib.Topology.Connected.Clopen

Goal state before:
pp: α : Type u
inst✝ : TopologicalSpace α
s : Set α
⊢ (s.Nonempty ∧ ∀ (u v : Set α), IsOpen[inst✝] u → IsOpen[inst✝] v → s ⊆ u ∪ v → s ∩ (u ∩ v) = ∅ → s ⊆ u ∨ s ⊆ v) ↔
    ∀ (U : Finset (Set α)),
      (∀ (u v : Set α), u ∈ U → v ∈ U → (s ∩ (u ∩ v)).Nonempty → u = v) →
        (∀ u ∈ U, IsOpen[inst✝] u) → s ⊆ ⋃₀ ↑U → ∃ u ∈ U, s ⊆ u

Tactic:
]

Goal state after:
α : Type u
inst✝ : TopologicalSpace α
s : Set α
⊢ (s.Nonempty ∧ ∀ (u v : Set α), IsOpen[inst✝] u → IsOpen[inst✝] v → s ⊆ u ∪ v → s ∩ (u ∩ v) = ∅ → s ⊆ u ∨ s ⊆ v) ↔
    ∀ (U : Finset (Set α)),
      (∀ (u v : Set α), u ∈ U → v ∈ U → (s ∩ (u ∩ v)).Nonempty → u = v) →
        (∀ u ∈ U, IsOpen[inst✝] u) → s ⊆ ⋃₀ ↑U → ∃ u ∈ U, s ⊆ u
Module: Mathlib.Topology.Separation.Regular

Goal state before:
pp: X : Type u
inst✝ : TopologicalSpace X
⊢ (∀ (b : X) (a : Set X), IsClosed[inst✝] aᶜ → b ∉ aᶜ → Disjoint (𝓝ˢ aᶜ) (𝓝 b)) ↔
    ∀ (x : X), (𝓝 x).lift' closure[inst✝] ≤ 𝓝 x

Tactic:
]

Goal state after:
X : Type u
inst✝ : TopologicalSpace X
⊢ (∀ (b : X) (a : Set X), IsClosed[inst✝] aᶜ → b ∉ aᶜ → Disjoint (𝓝ˢ aᶜ) (𝓝 b)) ↔
    ∀ (x : X), (𝓝 x).lift' closure[inst✝] ≤ 𝓝 x
Module: Mathlib.Topology.Compactness.Lindelof

Goal state before:
pp: X : Type u
inst✝ : TopologicalSpace X
s : Set X
ι : Type v
hs : IsLindelof s
U : ι → Set X
hUo : ∀ (i : ι), IsOpen[inst✝] (U i)
hsU : s ⊆ ⋃ i, U i
s✝ t✝ : Set X
hst : s✝ ⊆ t✝
r : Set ι
hrcountable : r.Countable
hsub : t✝ ⊆ ⋃ i ∈ r, U i
⊢ ∃ r, r.Countable ∧ s✝ ⊆ ⋃ i ∈ r, U i

Tactic:
exact ⟨r, hrcountable, Subset.trans hst hsub⟩

Goal state after:
Module: Mathlib.Topology.Separation.Regular

Goal state before:
pp: X : Type u
inst✝ : TopologicalSpace X
tfae_1_iff_5 : RegularSpace X ↔ ∀ (x : X), (𝓝 x).lift' closure[inst✝] ≤ 𝓝 x
tfae_5_to_6 : (∀ (x : X), (𝓝 x).lift' closure[inst✝] ≤ 𝓝 x) → ∀ (x : X), (𝓝 x).lift' closure[inst✝] = 𝓝 x
H : ∀ (x : X), (𝓝 x).lift' closure[inst✝] = 𝓝 x
a : X
s : Set X
hs : s ∈ (𝓝 a).lift' closure[inst✝]
⊢ ∃ t ∈ 𝓝 a, IsClosed[inst✝] t ∧ t ⊆ s

Tactic:
]

Goal state after:
X : Type u
inst✝ : TopologicalSpace X
tfae_1_iff_5 : RegularSpace X ↔ ∀ (x : X), (𝓝 x).lift' closure[inst✝] ≤ 𝓝 x
tfae_5_to_6 : (∀ (x : X), (𝓝 x).lift' closure[inst✝] ≤ 𝓝 x) → ∀ (x : X), (𝓝 x).lift' closure[inst✝] = 𝓝 x
H : ∀ (x : X), (𝓝 x).lift' closure[inst✝] = 𝓝 x
a : X
s : Set X
hs : s ∈ (𝓝 a).lift' closure[inst✝]
⊢ ∃ t ∈ 𝓝 a, IsClosed[inst✝] t ∧ t ⊆ s
Module: Mathlib.Topology.Separation.Regular

Goal state before:
pp: X : Type u
inst✝ : TopologicalSpace X
tfae_1_iff_5 : RegularSpace X ↔ ∀ (x : X), (𝓝 x).lift' closure[inst✝] ≤ 𝓝 x
tfae_5_to_6 : (∀ (x : X), (𝓝 x).lift' closure[inst✝] ≤ 𝓝 x) → ∀ (x : X), (𝓝 x).lift' closure[inst✝] = 𝓝 x
tfae_6_to_4 : (∀ (x : X), (𝓝 x).lift' closure[inst✝] = 𝓝 x) → ∀ (x : X), ∀ s ∈ 𝓝 x, ∃ t ∈ 𝓝 x, IsClosed[inst✝] t ∧ t ⊆ s
H : ∀ (x : X), ∀ s ∈ 𝓝 x, ∃ t ∈ 𝓝 x, IsClosed[inst✝] t ∧ t ⊆ s
s : Set X
a : X
ha : a ∉ closure[inst✝] s
⊢ a ∈ (closure[inst✝] s)ᶜ

Tactic:
]

Goal state after:
X : Type u
inst✝ : TopologicalSpace X
tfae_1_iff_5 : RegularSpace X ↔ ∀ (x : X), (𝓝 x).lift' closure[inst✝] ≤ 𝓝 x
tfae_5_to_6 : (∀ (x : X), (𝓝 x).lift' closure[inst✝] ≤ 𝓝 x) → ∀ (x : X), (𝓝 x).lift' closure[inst✝] = 𝓝 x
tfae_6_to_4 : (∀ (x : X), (𝓝 x).lift' closure[inst✝] = 𝓝 x) → ∀ (x : X), ∀ s ∈ 𝓝 x, ∃ t ∈ 𝓝 x, IsClosed[inst✝] t ∧ t ⊆ s
H : ∀ (x : X), ∀ s ∈ 𝓝 x, ∃ t ∈ 𝓝 x, IsClosed[inst✝] t ∧ t ⊆ s
s : Set X
a : X
ha : a ∉ closure[inst✝] s
⊢ a ∈ (closure[inst✝] s)ᶜ
Module: Mathlib.Topology.Separation.Regular

Goal state before:
pp: X : Type u
inst✝ : TopologicalSpace X
tfae_1_iff_5 : RegularSpace X ↔ ∀ (x : X), (𝓝 x).lift' closure[inst✝] ≤ 𝓝 x
tfae_5_to_6 : (∀ (x : X), (𝓝 x).lift' closure[inst✝] ≤ 𝓝 x) → ∀ (x : X), (𝓝 x).lift' closure[inst✝] = 𝓝 x
tfae_6_to_4 : (∀ (x : X), (𝓝 x).lift' closure[inst✝] = 𝓝 x) → ∀ (x : X), ∀ s ∈ 𝓝 x, ∃ t ∈ 𝓝 x, IsClosed[inst✝] t ∧ t ⊆ s
H : ∀ (x : X), ∀ s ∈ 𝓝 x, ∃ t ∈ 𝓝 x, IsClosed[inst✝] t ∧ t ⊆ s
s : Set X
a : X
ha : a ∉ closure[inst✝] s
ha' : sᶜ ∈ 𝓝 a
U : Set X
hU : U ∈ 𝓝 a
hUc : IsClosed[inst✝] U
hUs : U ⊆ sᶜ
⊢ U ⊆ sᶜ

Tactic:
]

Goal state after:
X : Type u
inst✝ : TopologicalSpace X
tfae_1_iff_5 : RegularSpace X ↔ ∀ (x : X), (𝓝 x).lift' closure[inst✝] ≤ 𝓝 x
tfae_5_to_6 : (∀ (x : X), (𝓝 x).lift' closure[inst✝] ≤ 𝓝 x) → ∀ (x : X), (𝓝 x).lift' closure[inst✝] = 𝓝 x
tfae_6_to_4 : (∀ (x : X), (𝓝 x).lift' closure[inst✝] = 𝓝 x) → ∀ (x : X), ∀ s ∈ 𝓝 x, ∃ t ∈ 𝓝 x, IsClosed[inst✝] t ∧ t ⊆ s
H : ∀ (x : X), ∀ s ∈ 𝓝 x, ∃ t ∈ 𝓝 x, IsClosed[inst✝] t ∧ t ⊆ s
s : Set X
a : X
ha : a ∉ closure[inst✝] s
ha' : sᶜ ∈ 𝓝 a
U : Set X
hU : U ∈ 𝓝 a
hUc : IsClosed[inst✝] U
hUs : U ⊆ sᶜ
⊢ U ⊆ sᶜ
Module: Mathlib.Topology.Connected.Clopen

Goal state before:
pp: case refine_3
α : Type u
inst✝ : TopologicalSpace α
s : Set α
h :
  ∀ (U : Finset (Set α)),
    (∀ (u v : Set α), u ∈ U → v ∈ U → (s ∩ (u ∩ v)).Nonempty → u = v) →
      (∀ u ∈ U, IsOpen[inst✝] u) → s ⊆ ⋃₀ ↑U → ∃ u ∈ U, s ⊆ u
u v : Set α
hu : IsOpen[inst✝] u
hv : IsOpen[inst✝] v
hs : s ⊆ u ∪ v
hsuv : ¬(s ∩ (u ∩ v)).Nonempty
⊢ s ⊆ u ∨ s ⊆ v

Tactic:
]

Goal state after:
case refine_3
α : Type u
inst✝ : TopologicalSpace α
s : Set α
h :
  ∀ (U : Finset (Set α)),
    (∀ (u v : Set α), u ∈ U → v ∈ U → (s ∩ (u ∩ v)).Nonempty → u = v) →
      (∀ u ∈ U, IsOpen[inst✝] u) → s ⊆ ⋃₀ ↑U → ∃ u ∈ U, s ⊆ u
u v : Set α
hu : IsOpen[inst✝] u
hv : IsOpen[inst✝] v
hs : s ⊆ u ∪ v
hsuv : ¬(s ∩ (u ∩ v)).Nonempty
⊢ s ⊆ u ∨ s ⊆ v
Module: Mathlib.Topology.Compactness.Lindelof

Goal state before:
pp: case right
X : Type u
inst✝ : TopologicalSpace X
s : Set X
hs : IsLindelof s
U : X → Set X
hU : ∀ x ∈ s, U x ∈ 𝓝 x
t : Set ↑s
htc : t.Countable
htsub : s ⊆ ⋃ x ∈ t, U ↑x
this : ⋃ x ∈ t, U ↑x = ⋃ x ∈ Subtype.val '' t, U x
⊢ s ⊆ ⋃ x ∈ t, U ↑x

Tactic:
]

Goal state after:
case right
X : Type u
inst✝ : TopologicalSpace X
s : Set X
hs : IsLindelof s
U : X → Set X
hU : ∀ x ∈ s, U x ∈ 𝓝 x
t : Set ↑s
htc : t.Countable
htsub : s ⊆ ⋃ x ∈ t, U ↑x
this : ⋃ x ∈ t, U ↑x = ⋃ x ∈ Subtype.val '' t, U x
⊢ s ⊆ ⋃ x ∈ t, U ↑x
Module: Mathlib.Topology.Connected.Basic

Goal state before:
pp: α : Type u
inst✝ : TopologicalSpace α
s u v : Set α
hu : IsOpen[inst✝] u
hv : IsOpen[inst✝] v
huv : Disjoint u v
hsuv : s ⊆ u ∪ v
hsu : (s ∩ u).Nonempty
hs : IsPreconnected s
⊢ Disjoint s v

Tactic:
by_contra hsv

Goal state after:
α : Type u
inst✝ : TopologicalSpace α
s u v : Set α
hu : IsOpen[inst✝] u
hv : IsOpen[inst✝] v
huv : Disjoint u v
hsuv : s ⊆ u ∪ v
hsu : (s ∩ u).Nonempty
hs : IsPreconnected s
hsv : ¬Disjoint s v
⊢ False
Module: Mathlib.Topology.Connected.Clopen

Goal state before:
pp: case refine_3
α : Type u
inst✝ : TopologicalSpace α
s : Set α
h :
  ∀ (U : Finset (Set α)),
    (∀ (u v : Set α), u ∈ U → v ∈ U → (s ∩ (u ∩ v)).Nonempty → u = v) →
      (∀ u ∈ U, IsOpen[inst✝] u) → s ⊆ ⋃₀ ↑U → ∃ u ∈ U, s ⊆ u
u v : Set α
hu : IsOpen[inst✝] u
hv : IsOpen[inst✝] v
hs : s ⊆ u ∪ v
hsuv : ¬(s ∩ (u ∩ v)).Nonempty
this : ¬(s ∩ (v ∩ u)).Nonempty
⊢ s ⊆ u ∨ s ⊆ v

Tactic:
]

Goal state after:
case refine_3
α : Type u
inst✝ : TopologicalSpace α
s : Set α
h :
  ∀ (U : Finset (Set α)),
    (∀ (u v : Set α), u ∈ U → v ∈ U → (s ∩ (u ∩ v)).Nonempty → u = v) →
      (∀ u ∈ U, IsOpen[inst✝] u) → s ⊆ ⋃₀ ↑U → ∃ u ∈ U, s ⊆ u
u v : Set α
hu : IsOpen[inst✝] u
hv : IsOpen[inst✝] v
hs : s ⊆ u ∪ v
hsuv : ¬(s ∩ (u ∩ v)).Nonempty
this : ¬(s ∩ (v ∩ u)).Nonempty
⊢ s ⊆ u ∨ s ⊆ v
Module: Mathlib.Topology.Connected.Basic

Goal state before:
pp: α : Type u
inst✝ : TopologicalSpace α
s u v : Set α
hu : IsOpen[inst✝] u
hv : IsOpen[inst✝] v
huv : Disjoint u v
hsuv : s ⊆ u ∪ v
hsu : (s ∩ u).Nonempty
hs : IsPreconnected s
hsv : (s ∩ v).Nonempty
⊢ False

Tactic:
]

Goal state after:
α : Type u
inst✝ : TopologicalSpace α
s u v : Set α
hu : IsOpen[inst✝] u
hv : IsOpen[inst✝] v
huv : Disjoint u v
hsuv : s ⊆ u ∪ v
hsu : (s ∩ u).Nonempty
hs : IsPreconnected s
hsv : (s ∩ v).Nonempty
⊢ False
Module: Mathlib.Topology.Separation.Regular

Goal state before:
pp: X : Type u_1
inst✝ : TopologicalSpace X
s : Set (Set X)
h : inst✝ = generateFrom s
h' : ∀ t ∈ s, ∀ a ∈ t, Disjoint (𝓝ˢ tᶜ) (𝓝 a)
a : X
t : Set X
ht : IsOpen[generateFrom s] t
ha : a ∉ tᶜ
⊢ Disjoint (𝓝ˢ tᶜ) (𝓝 a)

Tactic:
]

Goal state after:
X : Type u_1
inst✝ : TopologicalSpace X
s : Set (Set X)
h : inst✝ = generateFrom s
h' : ∀ t ∈ s, ∀ a ∈ t, Disjoint (𝓝ˢ tᶜ) (𝓝 a)
a : X
t : Set X
ht : IsOpen[generateFrom s] t
ha : a ∉ tᶜ
⊢ Disjoint (𝓝ˢ tᶜ) (𝓝 a)
Module: Mathlib.Topology.Separation.Regular

Goal state before:
pp: X : Type u_1
inst✝ : TopologicalSpace X
s : Set (Set X)
h : inst✝ = generateFrom s
h' : ∀ t ∈ s, ∀ a ∈ t, Disjoint (𝓝ˢ tᶜ) (𝓝 a)
a : X
t : Set X
ht : IsOpen[generateFrom s] t
ha : a ∈ t
⊢ Disjoint (𝓝ˢ tᶜ) (𝓝 a)

Tactic:
]

Goal state after:
X : Type u_1
inst✝ : TopologicalSpace X
s : Set (Set X)
h : inst✝ = generateFrom s
h' : ∀ t ∈ s, ∀ a ∈ t, Disjoint (𝓝ˢ tᶜ) (𝓝 a)
a : X
t : Set X
ht : IsOpen[generateFrom s] t
ha : a ∈ t
⊢ Disjoint (𝓝ˢ tᶜ) (𝓝 a)
Module: Mathlib.Topology.Separation.Regular

Goal state before:
pp: case sUnion
X : Type u_1
inst✝ : TopologicalSpace X
s : Set (Set X)
h : inst✝ = generateFrom s
h' : ∀ t ∈ s, ∀ a ∈ t, Disjoint (𝓝ˢ tᶜ) (𝓝 a)
a : X
t✝ : Set X
S : Set (Set X)
a✝ : ∀ s_1 ∈ S, GenerateOpen s s_1
ih : ∀ s ∈ S, a ∈ s → Disjoint (𝓝ˢ sᶜ) (𝓝 a)
t : Set X
ht : t ∈ S
ha : a ∈ t
⊢ Disjoint (𝓝ˢ tᶜ) (𝓝 a)

Tactic:
]

Goal state after:
case sUnion
X : Type u_1
inst✝ : TopologicalSpace X
s : Set (Set X)
h : inst✝ = generateFrom s
h' : ∀ t ∈ s, ∀ a ∈ t, Disjoint (𝓝ˢ tᶜ) (𝓝 a)
a : X
t✝ : Set X
S : Set (Set X)
a✝ : ∀ s_1 ∈ S, GenerateOpen s s_1
ih : ∀ s ∈ S, a ∈ s → Disjoint (𝓝ˢ sᶜ) (𝓝 a)
t : Set X
ht : t ∈ S
ha : a ∈ t
⊢ Disjoint (𝓝ˢ tᶜ) (𝓝 a)
Module: Mathlib.Topology.Separation.Regular

Goal state before:
pp: X : Type u_1
Y : Type u_2
inst✝¹ : TopologicalSpace X
inst✝ : RegularSpace X
x : X
s : Set X
x✝¹ x✝ : X
h : ¬x✝¹ ⤳ x✝
⊢ ¬x✝¹ ⤳ x✝

Tactic:
]

Goal state after:
X : Type u_1
Y : Type u_2
inst✝¹ : TopologicalSpace X
inst✝ : RegularSpace X
x : X
s : Set X
x✝¹ x✝ : X
h : ¬x✝¹ ⤳ x✝
⊢ ¬x✝¹ ⤳ x✝
Module: Mathlib.Topology.Connected.Clopen

Goal state before:
pp: case mp
α : Type u
inst✝ : TopologicalSpace α
s : Set α
h :
  ∀ (t t' : Set α),
    IsClosed[inst✝] t → IsClosed[inst✝] t' → s ⊆ t ∪ t' → (s ∩ t).Nonempty → (s ∩ t').Nonempty → (s ∩ (t ∩ t')).Nonempty
u v : Set α
hu : IsClosed[inst✝] u
hv : IsClosed[inst✝] v
hs : s ⊆ u ∪ v
huv : s ∩ (u ∩ v) = ∅
⊢ s ⊆ u ∨ s ⊆ v

Tactic:
]

Goal state after:
case mp
α : Type u
inst✝ : TopologicalSpace α
s : Set α
h :
  ∀ (t t' : Set α),
    IsClosed[inst✝] t → IsClosed[inst✝] t' → s ⊆ t ∪ t' → (s ∩ t).Nonempty → (s ∩ t').Nonempty → (s ∩ (t ∩ t')).Nonempty
u v : Set α
hu : IsClosed[inst✝] u
hv : IsClosed[inst✝] v
hs : s ⊆ u ∪ v
huv : s ∩ (u ∩ v) = ∅
⊢ s ⊆ u ∨ s ⊆ v
Module: Mathlib.Topology.Separation.Regular

Goal state before:
pp: X : Type u_1
Y : Type u_2
inst✝² : TopologicalSpace X
inst✝¹ : RegularSpace X
inst✝ : TopologicalSpace Y
f : Y → X
hf : IsInducing f
b : Y
⊢ (comap f (𝓝 (f b))).HasBasis (?m.10 b) (?m.11 b)

Tactic:
]

Goal state after:
X : Type u_1
Y : Type u_2
inst✝² : TopologicalSpace X
inst✝¹ : RegularSpace X
inst✝ : TopologicalSpace Y
f : Y → X
hf : IsInducing f
b : Y
⊢ (comap f (𝓝 (f b))).HasBasis (?m.10 b) (?m.11 b)
Module: Mathlib.Topology.Connected.Clopen

Goal state before:
pp: case mpr
α : Type u
inst✝ : TopologicalSpace α
s : Set α
h : ∀ (u v : Set α), IsClosed[inst✝] u → IsClosed[inst✝] v → s ⊆ u ∪ v → s ∩ (u ∩ v) = ∅ → s ⊆ u ∨ s ⊆ v
⊢ ∀ (t t' : Set α),
    IsClosed[inst✝] t → IsClosed[inst✝] t' → s ⊆ t ∪ t' → (s ∩ t).Nonempty → (s ∩ t').Nonempty → (s ∩ (t ∩ t')).Nonempty

Tactic:
]

Goal state after:
case mpr
α : Type u
inst✝ : TopologicalSpace α
s : Set α
h : ∀ (u v : Set α), IsClosed[inst✝] u → IsClosed[inst✝] v → s ⊆ u ∪ v → s ∩ (u ∩ v) = ∅ → s ⊆ u ∨ s ⊆ v
⊢ ∀ (t t' : Set α),
    IsClosed[inst✝] t → IsClosed[inst✝] t' → s ⊆ t ∪ t' → (s ∩ t).Nonempty → (s ∩ t').Nonempty → (s ∩ (t ∩ t')).Nonempty
Module: Mathlib.Topology.Compactness.Lindelof

Goal state before:
pp: X : Type u
inst✝¹ : TopologicalSpace X
s : Set X
ι : Type v
inst✝ : Nonempty ι
hs : IsLindelof s
U : ι → Set X
hUo : ∀ (i : ι), IsOpen[inst✝¹] (U i)
hsU : s ⊆ ⋃ i, U i
c : Set ι
c_count : c.Countable
c_cov : s ⊆ ⋃ i ∈ c, U i
c_nonempty : c.Nonempty
f : ℕ → ↑c
f_surj : Function.Surjective f
x : ι
hx : x ∈ c
n : ℕ
hn : f n = ⟨x, hx⟩
⊢ U x = U ↑⟨x, hx⟩

Tactic:
]

Goal state after:
Module: Mathlib.Topology.Separation.Regular

Goal state before:
pp: X : Type u_3
T : Set (TopologicalSpace X)
h : ∀ t ∈ T, RegularSpace X
x✝ : TopologicalSpace X := sInf T
a : X
⊢ (⨅ i, 𝓝 a).HasBasis (fun If ↦ If.fst.Finite ∧ ∀ (i : ↑If.fst), If.snd i ∈ 𝓝 a ∧ IsClosed[↑↑i] (If.snd i)) fun If ↦
    ⋂ i, If.snd i

Tactic:
]

Goal state after:
X : Type u_3
T : Set (TopologicalSpace X)
h : ∀ t ∈ T, RegularSpace X
x✝ : TopologicalSpace X := sInf T
a : X
⊢ (⨅ i, 𝓝 a).HasBasis (fun If ↦ If.fst.Finite ∧ ∀ (i : ↑If.fst), If.snd i ∈ 𝓝 a ∧ IsClosed[↑↑i] (If.snd i)) fun If ↦
    ⋂ i, If.snd i
Module: Mathlib.Topology.Separation.Regular

Goal state before:
pp: X : Type u_3
t₁ t₂ : TopologicalSpace X
h₁ : RegularSpace X
h₂ : RegularSpace X
⊢ RegularSpace X

Tactic:
]

Goal state after:
X : Type u_3
t₁ t₂ : TopologicalSpace X
h₁ : RegularSpace X
h₂ : RegularSpace X
⊢ RegularSpace X
Module: Mathlib.Topology.Compactness.Lindelof

Goal state before:
pp: X : Type u
inst✝¹ : TopologicalSpace X
s : Set X
l : Filter X
inst✝ : CountableInterFilter l
hs : IsLindelof s
H : ∀ x ∈ s, Disjoint (𝓝 x) l
U : X → Set X
hUl : ∀ x ∈ s, (U x)ᶜ ∈ l
hxU : ∀ x ∈ s, x ∈ U x
hUo : ∀ x ∈ s, IsOpen[inst✝¹] (U x)
t : Set X
htc : t.Countable
hts : ∀ x ∈ t, x ∈ s
hst : s ⊆ ⋃ x ∈ t, U x
⊢ ⋂ i ∈ t, (U i)ᶜ ∈ l

Tactic:
]

Goal state after:
X : Type u
inst✝¹ : TopologicalSpace X
s : Set X
l : Filter X
inst✝ : CountableInterFilter l
hs : IsLindelof s
H : ∀ x ∈ s, Disjoint (𝓝 x) l
U : X → Set X
hUl : ∀ x ∈ s, (U x)ᶜ ∈ l
hxU : ∀ x ∈ s, x ∈ U x
hUo : ∀ x ∈ s, IsOpen[inst✝¹] (U x)
t : Set X
htc : t.Countable
hts : ∀ x ∈ t, x ∈ s
hst : s ⊆ ⋃ x ∈ t, U x
⊢ ⋂ i ∈ t, (U i)ᶜ ∈ l
Module: Mathlib.Topology.Separation.Regular

Goal state before:
pp: case inl
X : Type u_1
inst✝² : TopologicalSpace X
s t : Set X
inst✝¹ : LindelofSpace X
inst✝ : RegularSpace X
s_cl : IsClosed[inst✝²] s
t_cl : IsClosed[inst✝²] t
st_dis : Disjoint s t
empty_X : IsEmpty X
⊢ _root_.HasSeparatingCover ∅ t

Tactic:
]

Goal state after:
case inl
X : Type u_1
inst✝² : TopologicalSpace X
s t : Set X
inst✝¹ : LindelofSpace X
inst✝ : RegularSpace X
s_cl : IsClosed[inst✝²] s
t_cl : IsClosed[inst✝²] t
st_dis : Disjoint s t
empty_X : IsEmpty X
⊢ _root_.HasSeparatingCover ∅ t
Module: Mathlib.Topology.Compactness.Lindelof

Goal state before:
pp: X : Type u
inst✝ : TopologicalSpace X
s : Set X
ι : Type v
hs : IsLindelof s
t : ι → Set X
htc : ∀ (i : ι), IsClosed[inst✝] (t i)
hst : s ∩ ⋂ i, t i = ∅
U : ι → Set X := tᶜ
hUo : ∀ (i : ι), IsOpen[inst✝] (U i)
⊢ s ⊆ (⋂ i, t i)ᶜ

Tactic:
]

Goal state after:
X : Type u
inst✝ : TopologicalSpace X
s : Set X
ι : Type v
hs : IsLindelof s
t : ι → Set X
htc : ∀ (i : ι), IsClosed[inst✝] (t i)
hst : s ∩ ⋂ i, t i = ∅
U : ι → Set X := tᶜ
hUo : ∀ (i : ι), IsOpen[inst✝] (U i)
⊢ s ⊆ (⋂ i, t i)ᶜ
Module: Mathlib.Topology.Compactness.Lindelof

Goal state before:
pp: case right
X : Type u
inst✝ : TopologicalSpace X
s : Set X
ι : Type v
hs : IsLindelof s
t : ι → Set X
htc : ∀ (i : ι), IsClosed[inst✝] (t i)
hst : s ∩ ⋂ i, t i = ∅
U : ι → Set X := tᶜ
hUo : ∀ (i : ι), IsOpen[inst✝] (U i)
hsU : s ⊆ ⋃ i, U i
u : Set ι
hucount : u.Countable
husub : Disjoint (⋃ i ∈ u, U i)ᶜ s
⊢ s ∩ ⋂ i ∈ u, t i = ∅

Tactic:
]

Goal state after:
case right
X : Type u
inst✝ : TopologicalSpace X
s : Set X
ι : Type v
hs : IsLindelof s
t : ι → Set X
htc : ∀ (i : ι), IsClosed[inst✝] (t i)
hst : s ∩ ⋂ i, t i = ∅
U : ι → Set X := tᶜ
hUo : ∀ (i : ι), IsOpen[inst✝] (U i)
hsU : s ⊆ ⋃ i, U i
u : Set ι
hucount : u.Countable
husub : Disjoint (⋃ i ∈ u, U i)ᶜ s
⊢ s ∩ ⋂ i ∈ u, t i = ∅
Module: Mathlib.Topology.Connected.Basic

Goal state before:
pp: case insert
ι : Type u_1
X : ι → Type u_2
inst✝ : (i : ι) → TopologicalSpace (X i)
s : (i : ι) → Set (X i)
hs : ∀ (i : ι), IsPreconnected (s i)
u v : Set ((i : ι) → X i)
uo : IsOpen[Pi.topologicalSpace] u
vo : IsOpen[Pi.topologicalSpace] v
hsuv : univ.pi s ⊆ u ∪ v
f : (i : ι) → X i
hfs : f ∈ univ.pi s
hfu : f ∈ u
g : (i : ι) → X i
hgs : g ∈ univ.pi s
hgv : g ∈ v
i : ι
I : Finset ι
a✝ : i ∉ I
ihI : I.piecewise f g ∈ u → (univ.pi s ∩ (u ∩ v)).Nonempty
hI : update (I.piecewise f g) i (f i) ∈ u
⊢ (univ.pi s ∩ (u ∩ v)).Nonempty

Tactic:
]

Goal state after:
case insert
ι : Type u_1
X : ι → Type u_2
inst✝ : (i : ι) → TopologicalSpace (X i)
s : (i : ι) → Set (X i)
hs : ∀ (i : ι), IsPreconnected (s i)
u v : Set ((i : ι) → X i)
uo : IsOpen[Pi.topologicalSpace] u
vo : IsOpen[Pi.topologicalSpace] v
hsuv : univ.pi s ⊆ u ∪ v
f : (i : ι) → X i
hfs : f ∈ univ.pi s
hfu : f ∈ u
g : (i : ι) → X i
hgs : g ∈ univ.pi s
hgv : g ∈ v
i : ι
I : Finset ι
a✝ : i ∉ I
ihI : I.piecewise f g ∈ u → (univ.pi s ∩ (u ∩ v)).Nonempty
hI : update (I.piecewise f g) i (f i) ∈ u
⊢ (univ.pi s ∩ (u ∩ v)).Nonempty