mathlib-initiative/mathlib-tactics huggingface dataset:
Module: Mathlib.Topology.Category.TopCat.Sphere

Goal state before:
pp: n : ℕ
x : EuclideanSpace ℝ (Fin n)
hx : x ∈ Metric.sphere 0 1
y : EuclideanSpace ℝ (Fin n)
hy : y ∈ Metric.sphere 0 1
h :
  (ConcreteCategory.hom (diskBoundaryInclusion n)) { down := ⟨x, hx⟩ } =
    (ConcreteCategory.hom (diskBoundaryInclusion n)) { down := ⟨y, hy⟩ }
⊢ { down := ⟨x, hx⟩ } = { down := ⟨y, hy⟩ }

Tactic:
obtain rfl : x = y := by simpa [diskBoundaryInclusion, disk] using h

Goal state after:
n : ℕ
x : EuclideanSpace ℝ (Fin n)
hx hy : x ∈ Metric.sphere 0 1
h :
  (ConcreteCategory.hom (diskBoundaryInclusion n)) { down := ⟨x, hx⟩ } =
    (ConcreteCategory.hom (diskBoundaryInclusion n)) { down := ⟨x, hy⟩ }
⊢ { down := ⟨x, hx⟩ } = { down := ⟨x, hy⟩ }
Module: Mathlib.Topology.CWComplex.Classical.Finite

Goal state before:
pp: X✝ : Type u_1
inst✝² : TopologicalSpace X✝
C✝ D✝ : Set X✝
inst✝¹ : RelCWComplex C✝ D✝
X : Type u
inst✝ : TopologicalSpace X
C D : Set X
cell : ℕ → Type u
map : (n : ℕ) → cell n → PartialEquiv (Fin n → ℝ) X
finite_cell : ∀ (n : ℕ), _root_.Finite (cell n)
source_eq : ∀ (n : ℕ) (i : cell n), (map n i).source = ball 0 1
continuousOn : ∀ (n : ℕ) (i : cell n), ContinuousOn (↑(map n i)) (closedBall 0 1)
continuousOn_symm : ∀ (n : ℕ) (i : cell n), ContinuousOn (↑(map n i).symm) (map n i).target
pairwiseDisjoint' : univ.PairwiseDisjoint fun ni ↦ ↑(map ni.fst ni.snd) '' ball 0 1
disjointBase' : ∀ (n : ℕ) (i : cell n), Disjoint (↑(map n i) '' ball 0 1) D
mapsTo :
  ∀ (n : ℕ) (i : cell n), MapsTo (↑(map n i)) (sphere 0 1) (D ∪ ⋃ m, ⋃ (_ : m < n), ⋃ j, ↑(map m j) '' closedBall 0 1)
closed' :
  ∀ A ⊆ C,
    (∀ (n : ℕ) (j : cell n), IsClosed[inst✝] (A ∩ ↑(map n j) '' closedBall 0 1)) ∧ IsClosed[inst✝] (A ∩ D) →
      IsClosed[inst✝] A
isClosedBase : IsClosed[inst✝] D
union' : D ∪ ⋃ n, ⋃ j, ↑(map n j) '' closedBall 0 1 = C
n : ℕ
i : cell n
⊢ ∃ I, MapsTo (↑(map n i)) (sphere 0 1) (D ∪ ⋃ m, ⋃ (_ : m < n), ⋃ j ∈ I m, ↑(map m j) '' closedBall 0 1)

Tactic:
use fun m ↦ finite_univ.toFinset (s := (univ : Set (cell m)))

Goal state after:
case h
X✝ : Type u_1
inst✝² : TopologicalSpace X✝
C✝ D✝ : Set X✝
inst✝¹ : RelCWComplex C✝ D✝
X : Type u
inst✝ : TopologicalSpace X
C D : Set X
cell : ℕ → Type u
map : (n : ℕ) → cell n → PartialEquiv (Fin n → ℝ) X
finite_cell : ∀ (n : ℕ), _root_.Finite (cell n)
source_eq : ∀ (n : ℕ) (i : cell n), (map n i).source = ball 0 1
continuousOn : ∀ (n : ℕ) (i : cell n), ContinuousOn (↑(map n i)) (closedBall 0 1)
continuousOn_symm : ∀ (n : ℕ) (i : cell n), ContinuousOn (↑(map n i).symm) (map n i).target
pairwiseDisjoint' : univ.PairwiseDisjoint fun ni ↦ ↑(map ni.fst ni.snd) '' ball 0 1
disjointBase' : ∀ (n : ℕ) (i : cell n), Disjoint (↑(map n i) '' ball 0 1) D
mapsTo :
  ∀ (n : ℕ) (i : cell n), MapsTo (↑(map n i)) (sphere 0 1) (D ∪ ⋃ m, ⋃ (_ : m < n), ⋃ j, ↑(map m j) '' closedBall 0 1)
closed' :
  ∀ A ⊆ C,
    (∀ (n : ℕ) (j : cell n), IsClosed[inst✝] (A ∩ ↑(map n j) '' closedBall 0 1)) ∧ IsClosed[inst✝] (A ∩ D) →
      IsClosed[inst✝] A
isClosedBase : IsClosed[inst✝] D
union' : D ∪ ⋃ n, ⋃ j, ↑(map n j) '' closedBall 0 1 = C
n : ℕ
i : cell n
⊢ MapsTo (↑(map n i)) (sphere 0 1) (D ∪ ⋃ m, ⋃ (_ : m < n), ⋃ j ∈ (fun m ↦ ⋯.toFinset) m, ↑(map m j) '' closedBall 0 1)
Module: Mathlib.Topology.CWComplex.Classical.Finite

Goal state before:
pp: X✝ : Type u_1
inst✝² : TopologicalSpace X✝
C✝ D : Set X✝
inst✝¹ : RelCWComplex C✝ D
X : Type u
inst✝ : TopologicalSpace X
C : Set X
cell : ℕ → Type u
map : (n : ℕ) → cell n → PartialEquiv (Fin n → ℝ) X
finite_cell : ∀ (n : ℕ), _root_.Finite (cell n)
source_eq : ∀ (n : ℕ) (i : cell n), (map n i).source = ball 0 1
continuousOn : ∀ (n : ℕ) (i : cell n), ContinuousOn (↑(map n i)) (closedBall 0 1)
continuousOn_symm : ∀ (n : ℕ) (i : cell n), ContinuousOn (↑(map n i).symm) (map n i).target
pairwiseDisjoint' : univ.PairwiseDisjoint fun ni ↦ ↑(map ni.fst ni.snd) '' ball 0 1
mapsTo :
  ∀ (n : ℕ) (i : cell n), MapsTo (↑(map n i)) (sphere 0 1) (⋃ m, ⋃ (_ : m < n), ⋃ j, ↑(map m j) '' closedBall 0 1)
closed' : ∀ A ⊆ C, (∀ (n : ℕ) (j : cell n), IsClosed[inst✝] (A ∩ ↑(map n j) '' closedBall 0 1)) → IsClosed[inst✝] A
union' : ⋃ n, ⋃ j, ↑(map n j) '' closedBall 0 1 = C
n : ℕ
i : cell n
⊢ ∃ I, MapsTo (↑(map n i)) (sphere 0 1) (⋃ m, ⋃ (_ : m < n), ⋃ j ∈ I m, ↑(map m j) '' closedBall 0 1)

Tactic:
use fun m ↦ finite_univ.toFinset (s := (univ : Set (cell m)))

Goal state after:
case h
X✝ : Type u_1
inst✝² : TopologicalSpace X✝
C✝ D : Set X✝
inst✝¹ : RelCWComplex C✝ D
X : Type u
inst✝ : TopologicalSpace X
C : Set X
cell : ℕ → Type u
map : (n : ℕ) → cell n → PartialEquiv (Fin n → ℝ) X
finite_cell : ∀ (n : ℕ), _root_.Finite (cell n)
source_eq : ∀ (n : ℕ) (i : cell n), (map n i).source = ball 0 1
continuousOn : ∀ (n : ℕ) (i : cell n), ContinuousOn (↑(map n i)) (closedBall 0 1)
continuousOn_symm : ∀ (n : ℕ) (i : cell n), ContinuousOn (↑(map n i).symm) (map n i).target
pairwiseDisjoint' : univ.PairwiseDisjoint fun ni ↦ ↑(map ni.fst ni.snd) '' ball 0 1
mapsTo :
  ∀ (n : ℕ) (i : cell n), MapsTo (↑(map n i)) (sphere 0 1) (⋃ m, ⋃ (_ : m < n), ⋃ j, ↑(map m j) '' closedBall 0 1)
closed' : ∀ A ⊆ C, (∀ (n : ℕ) (j : cell n), IsClosed[inst✝] (A ∩ ↑(map n j) '' closedBall 0 1)) → IsClosed[inst✝] A
union' : ⋃ n, ⋃ j, ↑(map n j) '' closedBall 0 1 = C
n : ℕ
i : cell n
⊢ MapsTo (↑(map n i)) (sphere 0 1) (⋃ m, ⋃ (_ : m < n), ⋃ j ∈ (fun m ↦ ⋯.toFinset) m, ↑(map m j) '' closedBall 0 1)
Module: Mathlib.Topology.CWComplex.Classical.Finite

Goal state before:
pp: X✝ : Type u_1
inst✝² : TopologicalSpace X✝
C✝ D✝ : Set X✝
inst✝¹ : RelCWComplex C✝ D✝
X : Type u
inst✝ : TopologicalSpace X
C D : Set X
cell : ℕ → Type u
map : (n : ℕ) → cell n → PartialEquiv (Fin n → ℝ) X
eventually_isEmpty_cell : ∀ᶠ (n : ℕ) in Filter.atTop, IsEmpty (cell n)
finite_cell : ∀ (n : ℕ), _root_.Finite (cell n)
source_eq : ∀ (n : ℕ) (i : cell n), (map n i).source = ball 0 1
continuousOn : ∀ (n : ℕ) (i : cell n), ContinuousOn (↑(map n i)) (closedBall 0 1)
continuousOn_symm : ∀ (n : ℕ) (i : cell n), ContinuousOn (↑(map n i).symm) (map n i).target
pairwiseDisjoint' : univ.PairwiseDisjoint fun ni ↦ ↑(map ni.fst ni.snd) '' ball 0 1
disjointBase' : ∀ (n : ℕ) (i : cell n), Disjoint (↑(map n i) '' ball 0 1) D
mapsTo :
  ∀ (n : ℕ) (i : cell n), MapsTo (↑(map n i)) (sphere 0 1) (D ∪ ⋃ m, ⋃ (_ : m < n), ⋃ j, ↑(map m j) '' closedBall 0 1)
isClosedBase : IsClosed[inst✝] D
union' : D ∪ ⋃ n, ⋃ j, ↑(map n j) '' closedBall 0 1 = C
n : ℕ
i : cell n
⊢ ∃ I, MapsTo (↑(map n i)) (sphere 0 1) (D ∪ ⋃ m, ⋃ (_ : m < n), ⋃ j ∈ I m, ↑(map m j) '' closedBall 0 1)

Tactic:
use fun m ↦ finite_univ.toFinset (s := (univ : Set (cell m)))

Goal state after:
case h
X✝ : Type u_1
inst✝² : TopologicalSpace X✝
C✝ D✝ : Set X✝
inst✝¹ : RelCWComplex C✝ D✝
X : Type u
inst✝ : TopologicalSpace X
C D : Set X
cell : ℕ → Type u
map : (n : ℕ) → cell n → PartialEquiv (Fin n → ℝ) X
eventually_isEmpty_cell : ∀ᶠ (n : ℕ) in Filter.atTop, IsEmpty (cell n)
finite_cell : ∀ (n : ℕ), _root_.Finite (cell n)
source_eq : ∀ (n : ℕ) (i : cell n), (map n i).source = ball 0 1
continuousOn : ∀ (n : ℕ) (i : cell n), ContinuousOn (↑(map n i)) (closedBall 0 1)
continuousOn_symm : ∀ (n : ℕ) (i : cell n), ContinuousOn (↑(map n i).symm) (map n i).target
pairwiseDisjoint' : univ.PairwiseDisjoint fun ni ↦ ↑(map ni.fst ni.snd) '' ball 0 1
disjointBase' : ∀ (n : ℕ) (i : cell n), Disjoint (↑(map n i) '' ball 0 1) D
mapsTo :
  ∀ (n : ℕ) (i : cell n), MapsTo (↑(map n i)) (sphere 0 1) (D ∪ ⋃ m, ⋃ (_ : m < n), ⋃ j, ↑(map m j) '' closedBall 0 1)
isClosedBase : IsClosed[inst✝] D
union' : D ∪ ⋃ n, ⋃ j, ↑(map n j) '' closedBall 0 1 = C
n : ℕ
i : cell n
⊢ MapsTo (↑(map n i)) (sphere 0 1) (D ∪ ⋃ m, ⋃ (_ : m < n), ⋃ j ∈ (fun m ↦ ⋯.toFinset) m, ↑(map m j) '' closedBall 0 1)
Module: Mathlib.Topology.Category.Profinite.Nobeling.Basic

Goal state before:
pp: I : Type u
C : Set (I → Bool)
J K : I → Prop
inst✝¹ : (i : I) → Decidable (J i)
inst✝ : (i : I) → Decidable (K i)
h : ∀ (i : I), J i → K i
⊢ ProjRestricts C h ∘ ProjRestrict C K = ProjRestrict C J

Tactic:
by
  ext x i
  simp only [π, Proj, Function.comp_apply, ProjRestricts_coe, ProjRestrict_coe]
  simp_all

Goal state after:
Module: Mathlib.Topology.Category.Profinite.Nobeling.Basic

Goal state before:
pp: I : Type u
C : Set (I → Bool)
J K L : I → Prop
inst✝³ : (i : I) → Decidable (J i)
inst✝² : (i : I) → Decidable (K i)
inst✝¹ : (i : I) → Decidable (L i)
inst✝ : (s : Finset I) → (i : I) → Decidable (i ∈ s)
hC : IsCompact C
X : (Finset I)ᵒᵖ
⊢ ∀ ⦃Y : (Finset I)ᵒᵖ⦄ (f : X ⟶ Y),
    ((Functor.const (Finset I)ᵒᵖ).obj (of ↑C)).map f ≫
        ConcreteCategory.ofHom { toFun := ProjRestrict C fun x ↦ x ∈ unop Y, continuous_toFun := ⋯ } =
      ConcreteCategory.ofHom { toFun := ProjRestrict C fun x ↦ x ∈ unop X, continuous_toFun := ⋯ } ≫
        (spanFunctor hC).map f

Tactic:
Y

Goal state after:
I : Type u
C : Set (I → Bool)
J K L : I → Prop
inst✝³ : (i : I) → Decidable (J i)
inst✝² : (i : I) → Decidable (K i)
inst✝¹ : (i : I) → Decidable (L i)
inst✝ : (s : Finset I) → (i : I) → Decidable (i ∈ s)
hC : IsCompact C
X Y : (Finset I)ᵒᵖ
⊢ ∀ (f : X ⟶ Y),
    ((Functor.const (Finset I)ᵒᵖ).obj (of ↑C)).map f ≫
        ConcreteCategory.ofHom { toFun := ProjRestrict C fun x ↦ x ∈ unop Y, continuous_toFun := ⋯ } =
      ConcreteCategory.ofHom { toFun := ProjRestrict C fun x ↦ x ∈ unop X, continuous_toFun := ⋯ } ≫
        (spanFunctor hC).map f
Module: Mathlib.Topology.Category.Profinite.Nobeling.Basic

Goal state before:
pp: I : Type u
C : Set (I → Bool)
inst✝ : LinearOrder I
l : Products I
x : ↑C
⊢ (LocallyConstant.evalMonoidHom x) (eval C l) = if ∀ i ∈ ↑l, ↑x i = true then 1 else 0

Tactic:
eval,

Goal state after:
I : Type u
C : Set (I → Bool)
inst✝ : LinearOrder I
l : Products I
x : ↑C
⊢ (LocallyConstant.evalMonoidHom x) (List.map (e C) ↑l).prod = if ∀ i ∈ ↑l, ↑x i = true then 1 else 0
Module: Mathlib.Topology.Category.Profinite.Nobeling.Successor

Goal state before:
pp: case pos
I : Type u
C : Set (I → Bool)
inst✝¹ : LinearOrder I
inst✝ : WellFoundedLT I
o : Ordinal.{u}
hsC : contained C (Order.succ o)
ho : o < Ordinal.type fun x1 x2 ↦ x1 < x2
x : I → Bool
hx : x ∈ C1 C ho
i : I
hi : ¬ord I i = o
h : ord I i < o
⊢ x i = x i

pp: case neg
I : Type u
C : Set (I → Bool)
inst✝¹ : LinearOrder I
inst✝ : WellFoundedLT I
o : Ordinal.{u}
hsC : contained C (Order.succ o)
ho : o < Ordinal.type fun x1 x2 ↦ x1 < x2
x : I → Bool
hx : x ∈ C1 C ho
i : I
hi : ¬ord I i = o
h : ¬ord I i < o
⊢ false = x i

Tactic:
· rfl

Goal state after:
case neg
I : Type u
C : Set (I → Bool)
inst✝¹ : LinearOrder I
inst✝ : WellFoundedLT I
o : Ordinal.{u}
hsC : contained C (Order.succ o)
ho : o < Ordinal.type fun x1 x2 ↦ x1 < x2
x : I → Bool
hx : x ∈ C1 C ho
i : I
hi : ¬ord I i = o
h : ¬ord I i < o
⊢ false = x i
Module: Mathlib.Topology.Category.Profinite.Nobeling.ZeroLimit

Goal state before:
pp: I : Type u_1
inst✝ : LinearOrder I
⊢ eval {fun x ↦ false} default ≠ 0

Tactic:
by simp [eval, Products.eval, Products.nil, default]

Goal state after:
Module: Mathlib.Topology.Category.Profinite.Nobeling.Basic

Goal state before:
pp: case refine_1
I : Type u
inst✝¹ : LinearOrder I
inst✝ : WellFoundedLT I
o : Ordinal.{u}
ho : o < Ordinal.type fun x1 x2 ↦ x1 < x2
i : I
h : ord I i = o
⊢ term I ho = i

Tactic:
subst h

Goal state after:
case refine_1
I : Type u
inst✝¹ : LinearOrder I
inst✝ : WellFoundedLT I
i : I
ho : ord I i < Ordinal.type fun x1 x2 ↦ x1 < x2
⊢ term I ho = i
Module: Mathlib.Topology.Category.Profinite.Nobeling.ZeroLimit

Goal state before:
pp: case h
I : Type u
C : Set (I → Bool)
inst✝¹ : LinearOrder I
inst✝ : WellFoundedLT I
o₁ o₂ : Ordinal.{u}
h : o₁ ≤ o₂
l : Products I
gl : Products.isGood (π C fun x ↦ ord I x < o₁) l
x : ↑(π C fun x ↦ ord I x < o₂)
⊢ (eval (π C fun x ↦ ord I x < o₂) ⟨l, ⋯⟩) x = ((πs' C h) (eval (π C fun x ↦ ord I x < o₁) ⟨l, gl⟩)) x

Tactic:
eval,

Goal state after:
case h
I : Type u
C : Set (I → Bool)
inst✝¹ : LinearOrder I
inst✝ : WellFoundedLT I
o₁ o₂ : Ordinal.{u}
h : o₁ ≤ o₂
l : Products I
gl : Products.isGood (π C fun x ↦ ord I x < o₁) l
x : ↑(π C fun x ↦ ord I x < o₂)
⊢ (Products.eval (π C fun x ↦ ord I x < o₂) ↑⟨l, ⋯⟩) x = ((πs' C h) (eval (π C fun x ↦ ord I x < o₁) ⟨l, gl⟩)) x
Module: Mathlib.Topology.Category.Profinite.Nobeling.Basic

Goal state before:
pp: case refine_2
I : Type u
inst✝¹ : LinearOrder I
inst✝ : WellFoundedLT I
o : Ordinal.{u}
ho : o < Ordinal.type fun x1 x2 ↦ x1 < x2
i : I
h : term I ho = i
⊢ ord I i = o

Tactic:
subst h

Goal state after:
case refine_2
I : Type u
inst✝¹ : LinearOrder I
inst✝ : WellFoundedLT I
o : Ordinal.{u}
ho : o < Ordinal.type fun x1 x2 ↦ x1 < x2
⊢ ord I (term I ho) = o
Module: Mathlib.Topology.Category.Profinite.Nobeling.Successor

Goal state before:
pp: I : Type u
C : Set (I → Bool)
inst✝² : LinearOrder I
inst✝¹ : WellFoundedLT I
o : Ordinal.{u}
hsC : contained C (Order.succ o)
ho : o < Ordinal.type fun x1 x2 ↦ x1 < x2
inst✝ : Inhabited I
l : Products I
hl : ↑l ≠ []
hlh : (↑l).head! = term I ho
hlc : List.IsChain (fun x1 x2 ↦ x1 > x2) (term I ho :: ↑l.Tail)
x : ↑(C' C ho)
i : I
hi : i ∈ ↑l.Tail
⊢ ↑x i = SwapTrue o (↑x) i

Tactic:
simp only [SwapTrue, @eq_comm _ (x.val i), ite_eq_right_iff, ord_term ho]

Goal state after:
I : Type u
C : Set (I → Bool)
inst✝² : LinearOrder I
inst✝¹ : WellFoundedLT I
o : Ordinal.{u}
hsC : contained C (Order.succ o)
ho : o < Ordinal.type fun x1 x2 ↦ x1 < x2
inst✝ : Inhabited I
l : Products I
hl : ↑l ≠ []
hlh : (↑l).head! = term I ho
hlc : List.IsChain (fun x1 x2 ↦ x1 > x2) (term I ho :: ↑l.Tail)
x : ↑(C' C ho)
i : I
hi : i ∈ ↑l.Tail
⊢ term I ho = i → true = ↑x i
Module: Mathlib.Topology.Category.Profinite.Nobeling.Successor

Goal state before:
pp: I : Type u
C : Set (I → Bool)
inst✝² : LinearOrder I
inst✝¹ : WellFoundedLT I
o : Ordinal.{u}
hsC : contained C (Order.succ o)
ho : o < Ordinal.type fun x1 x2 ↦ x1 < x2
inst✝ : Inhabited I
l : Products I
hl : ↑l ≠ []
hlh : (↑l).head! = term I ho
hlc : List.IsChain (fun x1 x2 ↦ x1 > x2) (term I ho :: ↑l.Tail)
x : ↑(C' C ho)
hi' : ∀ i ∈ ↑l.Tail, ↑x i = SwapTrue o (↑x) i
H : (∀ i ∈ ↑l.Tail, ↑x i = true) = ∀ i ∈ ↑l.Tail, SwapTrue o (↑x) i = true
⊢ ((if ∀ i ∈ ↑l.Tail, SwapTrue o (↑x) i = true then (e C (term I ho)) ⟨SwapTrue o ↑x, ⋯⟩ else 0) -
      if ∀ i ∈ ↑l.Tail, ↑x i = true then (e C (term I ho)) ⟨↑x, ⋯⟩ else 0) =
    if ∀ i ∈ ↑(Tail ⟨term I ho :: ↑l.Tail, hlc⟩), ↑x i = true then 1 else 0

Tactic:
simp only [H]

Goal state after:
I : Type u
C : Set (I → Bool)
inst✝² : LinearOrder I
inst✝¹ : WellFoundedLT I
o : Ordinal.{u}
hsC : contained C (Order.succ o)
ho : o < Ordinal.type fun x1 x2 ↦ x1 < x2
inst✝ : Inhabited I
l : Products I
hl : ↑l ≠ []
hlh : (↑l).head! = term I ho
hlc : List.IsChain (fun x1 x2 ↦ x1 > x2) (term I ho :: ↑l.Tail)
x : ↑(C' C ho)
hi' : ∀ i ∈ ↑l.Tail, ↑x i = SwapTrue o (↑x) i
H : (∀ i ∈ ↑l.Tail, ↑x i = true) = ∀ i ∈ ↑l.Tail, SwapTrue o (↑x) i = true
⊢ ((if ∀ i ∈ ↑l.Tail, SwapTrue o (↑x) i = true then (e C (term I ho)) ⟨SwapTrue o ↑x, ⋯⟩ else 0) -
      if ∀ i ∈ ↑l.Tail, SwapTrue o (↑x) i = true then (e C (term I ho)) ⟨↑x, ⋯⟩ else 0) =
    if ∀ i ∈ ↑(Tail ⟨term I ho :: ↑l.Tail, hlc⟩), ↑x i = true then 1 else 0
Module: Mathlib.Topology.CWComplex.Classical.Basic

Goal state before:
pp: X : Type u_1
t : TopologicalSpace X
C D : Set X
inst✝¹ : T2Space X
inst✝ : RelCWComplex C D
n : ℕ
j : cell C n
⊢ Disjoint (interior D) (closedCell n j)

Tactic:
rw [disjoint_iff_inter_eq_empty]
  by_contra! h
  rw [← closure_openCell_eq_closedCell, inter_comm,
    closure_inter_open_nonempty_iff isOpen_interior] at h
  rcases h with ⟨x, xmemcell, xmemD⟩
  suffices x ∈ (skeletonLT C 0 : Set X) ∩ openCell n j by
    rwa [(disjoint_skeletonLT_openCell n.cast_nonneg').inter_eq] at this
  exact ⟨(skeletonLT C 0).base_subset (interior_subset xmemD), xmemcell⟩

Goal state after:
Module: Mathlib.Topology.Compactness.CompactSystem

Goal state before:
pp: α : Type u_1
S : Set (Set α)
h : ∀ (C : ℕ → Set α), (∀ (i : ℕ), C i ∈ S) → (∀ (n : ℕ), (dissipate C n).Nonempty) → (⋂ i, C i).Nonempty
h✝ : Nonempty α
s : ℕ → Set α
h' : ∀ (i : ℕ), s i ∈ insert Set.univ S
hd : ∀ (n : ℕ), (dissipate s n).Nonempty
h₀ : ∃ n, s n ∈ S
n : ℕ := Nat.find h₀
s' : ℕ → Set α := fun i ↦ if s i ∈ S then s i else s n
h₁ : ∀ (i : ℕ), s' i ∈ S
h₂ : ⋂ i, s i = ⋂ i, s' i
j : ℕ
hj : dissipate s' j ⊆ ∅
h₃ : ∀ (v : ℕ), n ≤ v → dissipate s v = dissipate s' v
⊢ dissipate s' (max j n) ⊆ ∅

Tactic:
exact (antitone_dissipate (Nat.le_max_left j n)).trans hj

Goal state after:
Module: Mathlib.Topology.Category.Profinite.Nobeling.Successor

Goal state before:
pp: case pos
I : Type u
C : Set (I → Bool)
inst✝² : LinearOrder I
inst✝¹ : WellFoundedLT I
o : Ordinal.{u}
hsC : contained C (Order.succ o)
ho : o < Ordinal.type fun x1 x2 ↦ x1 < x2
inst✝ : Inhabited I
l : Products I
hl : ↑l ≠ []
hlh : (↑l).head! = term I ho
hlc : List.IsChain (fun x1 x2 ↦ x1 > x2) (term I ho :: ↑l.Tail)
x : ↑(C' C ho)
hi' : ∀ i ∈ ↑l.Tail, ↑x i = SwapTrue o (↑x) i
H : (∀ i ∈ ↑l.Tail, ↑x i = true) = ∀ i ∈ ↑l.Tail, SwapTrue o (↑x) i = true
h₁ : ∀ i ∈ ↑l.Tail, SwapTrue o (↑x) i = true
h₂ : ∀ i ∈ ↑(Tail ⟨term I ho :: ↑l.Tail, hlc⟩), ↑x i = true
⊢ 1 - 0 = 1

pp: case pos.hnc
I : Type u
C : Set (I → Bool)
inst✝² : LinearOrder I
inst✝¹ : WellFoundedLT I
o : Ordinal.{u}
hsC : contained C (Order.succ o)
ho : o < Ordinal.type fun x1 x2 ↦ x1 < x2
inst✝ : Inhabited I
l : Products I
hl : ↑l ≠ []
hlh : (↑l).head! = term I ho
hlc : List.IsChain (fun x1 x2 ↦ x1 > x2) (term I ho :: ↑l.Tail)
x : ↑(C' C ho)
hi' : ∀ i ∈ ↑l.Tail, ↑x i = SwapTrue o (↑x) i
H : (∀ i ∈ ↑l.Tail, ↑x i = true) = ∀ i ∈ ↑l.Tail, SwapTrue o (↑x) i = true
h₁ : ∀ i ∈ ↑l.Tail, SwapTrue o (↑x) i = true
h₂ : ∀ i ∈ ↑(Tail ⟨term I ho :: ↑l.Tail, hlc⟩), ↑x i = true
⊢ ¬↑x (term I ho) = true

Tactic:
· rfl

Goal state after:
case pos.hnc
I : Type u
C : Set (I → Bool)
inst✝² : LinearOrder I
inst✝¹ : WellFoundedLT I
o : Ordinal.{u}
hsC : contained C (Order.succ o)
ho : o < Ordinal.type fun x1 x2 ↦ x1 < x2
inst✝ : Inhabited I
l : Products I
hl : ↑l ≠ []
hlh : (↑l).head! = term I ho
hlc : List.IsChain (fun x1 x2 ↦ x1 > x2) (term I ho :: ↑l.Tail)
x : ↑(C' C ho)
hi' : ∀ i ∈ ↑l.Tail, ↑x i = SwapTrue o (↑x) i
H : (∀ i ∈ ↑l.Tail, ↑x i = true) = ∀ i ∈ ↑l.Tail, SwapTrue o (↑x) i = true
h₁ : ∀ i ∈ ↑l.Tail, SwapTrue o (↑x) i = true
h₂ : ∀ i ∈ ↑(Tail ⟨term I ho :: ↑l.Tail, hlc⟩), ↑x i = true
⊢ ¬↑x (term I ho) = true
Module: Mathlib.Topology.ContinuousMap.Interval

Goal state before:
pp: α : Type u_1
inst✝⁵ : LinearOrder α
inst✝⁴ : TopologicalSpace α
inst✝³ : OrderTopology α
a b c : α
inst✝² : Fact (a ≤ b)
inst✝¹ : Fact (b ≤ c)
E : Type u_2
inst✝ : TopologicalSpace E
f : C(↑(Icc a b), E)
g : C(↑(Icc b c), E)
ι : Type u_3
p : Filter ι
F : ι → C(↑(Icc a b), E)
G : ι → C(↑(Icc b c), E)
hfg : ∀ᶠ (i : ι) in p, (F i) ⊤ = (G i) ⊥
hfg' : f ⊤ = g ⊥
hf :
  ∀ (K : Set ↑(Icc a b)),
    IsCompact K → ∀ (U : Set E), IsOpen[inst✝] U → MapsTo (⇑f) K U → ∀ᶠ (a_4 : ι) in p, MapsTo (⇑(F a_4)) K U
hg :
  ∀ (K : Set ↑(Icc b c)),
    IsCompact K → ∀ (U : Set E), IsOpen[inst✝] U → MapsTo (⇑g) K U → ∀ᶠ (a : ι) in p, MapsTo (⇑(G a)) K U
K : Set ↑(Icc a c)
hK : IsCompact K
U : Set E
hU : IsOpen[inst✝] U
hfgU : MapsTo (⇑(f.concat g)) K U
h : b ∈ Icc a c
K₁ : Set ↑(Icc a b) := ⇑projIccCM '' Subtype.val '' (K ∩ Iic ⟨b, h⟩)
⊢ ∀ᶠ (a_1 : ι) in p, MapsTo (⇑((F a_1).concat (G a_1))) K U

Tactic:
let K₂ : Set (Icc b c) := projIccCM '' Subtype.val '' (K ∩ Ici ⟨b, h⟩)

Goal state after:
α : Type u_1
inst✝⁵ : LinearOrder α
inst✝⁴ : TopologicalSpace α
inst✝³ : OrderTopology α
a b c : α
inst✝² : Fact (a ≤ b)
inst✝¹ : Fact (b ≤ c)
E : Type u_2
inst✝ : TopologicalSpace E
f : C(↑(Icc a b), E)
g : C(↑(Icc b c), E)
ι : Type u_3
p : Filter ι
F : ι → C(↑(Icc a b), E)
G : ι → C(↑(Icc b c), E)
hfg : ∀ᶠ (i : ι) in p, (F i) ⊤ = (G i) ⊥
hfg' : f ⊤ = g ⊥
hf :
  ∀ (K : Set ↑(Icc a b)),
    IsCompact K → ∀ (U : Set E), IsOpen[inst✝] U → MapsTo (⇑f) K U → ∀ᶠ (a_4 : ι) in p, MapsTo (⇑(F a_4)) K U
hg :
  ∀ (K : Set ↑(Icc b c)),
    IsCompact K → ∀ (U : Set E), IsOpen[inst✝] U → MapsTo (⇑g) K U → ∀ᶠ (a : ι) in p, MapsTo (⇑(G a)) K U
K : Set ↑(Icc a c)
hK : IsCompact K
U : Set E
hU : IsOpen[inst✝] U
hfgU : MapsTo (⇑(f.concat g)) K U
h : b ∈ Icc a c
K₁ : Set ↑(Icc a b) := ⇑projIccCM '' Subtype.val '' (K ∩ Iic ⟨b, h⟩)
K₂ : Set ↑(Icc b c) := ⇑projIccCM '' Subtype.val '' (K ∩ Ici ⟨b, h⟩)
⊢ ∀ᶠ (a_1 : ι) in p, MapsTo (⇑((F a_1).concat (G a_1))) K U
Module: Mathlib.Topology.Compactness.CountablyCompact

Goal state before:
pp: E : Type u_2
inst✝ : TopologicalSpace E
A : Set E
⊢ IsCountablyCompact A ↔ IsCountablyCompact univ

Tactic:
rw [Subtype.isCountablyCompact_iff, image_univ, Subtype.range_coe]

Goal state after:
Module: Mathlib.Topology.ContinuousMap.SecondCountableSpace

Goal state before:
pp: case a
X : Type u_1
Y : Type u_2
inst✝¹ : TopologicalSpace X
inst✝ : TopologicalSpace Y
S : Set (Set X)
T : Set (Set Y)
hS₁ : ∀ K ∈ S, IsCompact K
hT : IsTopologicalBasis T
hS₂ : ∀ (f : C(X, Y)) (x : X), ∀ V ∈ T, f x ∈ V → ∃ K ∈ S, K ∈ 𝓝 x ∧ MapsTo (⇑f) K V
⊢ generateFrom (image2 (fun K t ↦ {f | MapsTo (⇑f) K (⋃₀ t)}) S {t | t.Finite ∧ t ⊆ T}) ≤ compactOpen

Tactic:
refine le_of_nhds_le_nhds fun f ↦ ?_
    simp only [nhds_compactOpen, le_iInf_iff, le_principal_iff]
    intro K (hK : IsCompact K) U (hU : IsOpen U) hfKU
    simp only [TopologicalSpace.nhds_generateFrom]
    obtain ⟨t, htT, htf, hTU, hKT⟩ : ∃ t ⊆ T, t.Finite ∧ (∀ V ∈ t, V ⊆ U) ∧ f '' K ⊆ ⋃₀ t := by
      rw [hT.open_eq_sUnion' hU, mapsTo_iff_image_subset, sUnion_eq_biUnion] at hfKU
      obtain ⟨t, ht, hfin, htK⟩ :=
        (hK.image (map_continuous f)).elim_finite_subcover_image (fun V hV ↦ hT.isOpen hV.1) hfKU
      refine ⟨t, fun _ h ↦ (ht h).1, hfin, fun _ h ↦ (ht h).2, ?_⟩
      rwa [sUnion_eq_biUnion]
    rw [image_subset_iff] at hKT
    obtain ⟨s, hsS, hsf, hKs, hst⟩ : ∃ s ⊆ S, s.Finite ∧ K ⊆ ⋃₀ s ∧ MapsTo f (⋃₀ s) (⋃₀ t) := by
      have : ∀ x ∈ K, ∃ L ∈ S, L ∈ 𝓝 x ∧ MapsTo f L (⋃₀ t) := by
        intro x hx
        rcases hKT hx with ⟨V, hVt, hxV⟩
        rcases hS₂ f x V (htT hVt) hxV with ⟨L, hLS, hLx, hLV⟩
        exact ⟨L, hLS, hLx, hLV.mono_right <| subset_sUnion_of_mem hVt⟩
      choose! L hLS hLmem hLt using this
      rcases hK.elim_nhds_subcover L hLmem with ⟨s, hsK, hs⟩
      refine ⟨L '' s, image_subset_iff.2 fun x hx ↦ hLS x <| hsK x hx, s.finite_toSet.image _,
        by rwa [sUnion_image], ?_⟩
      rw [mapsTo_sUnion, forall_mem_image]
      exact fun x hx ↦ hLt x <| hsK x hx
    have hsub : (⋂ L ∈ s, {g : C(X, Y) | MapsTo g L (⋃₀ t)}) ⊆ {g | MapsTo g K U} := by
      simp only [← ofPred_forall, ← mapsTo_iUnion, ← sUnion_eq_biUnion]
      exact fun g hg ↦ hg.mono hKs (sUnion_subset hTU)
    refine mem_of_superset ((biInter_mem hsf).2 fun L hL ↦ ?_) hsub
    refine mem_iInf_of_mem _ <| mem_iInf_of_mem ?_ <| mem_principal_self _
    exact ⟨hst.mono_left (subset_sUnion_of_mem hL), mem_image2_of_mem (hsS hL) ⟨htf, htT⟩⟩

Goal state after: