mathlib-initiative/mathlib-tactics huggingface dataset:
Module: Mathlib.Topology.Compactness.CompactSystem

Goal state before:
pp: α : Type u_1
S : Set (Set α)
h : IsCompactSystem S
s : ℕ → Set α
⊢ (∀ (i : ℕ), s i ∈ insert ∅ S) → ⋂ i, s i = ∅ → ∃ n, dissipate s n = ∅

Tactic:
h'

Goal state after:
α : Type u_1
S : Set (Set α)
h : IsCompactSystem S
s : ℕ → Set α
h' : ∀ (i : ℕ), s i ∈ insert ∅ S
⊢ ⋂ i, s i = ∅ → ∃ n, dissipate s n = ∅
Module: Mathlib.Topology.Compactness.CompactSystem

Goal state before:
pp: case inr
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
⊢ (∀ (i : ℕ), s i ∈ insert Set.univ S) → (∀ (n : ℕ), (dissipate s n).Nonempty) → (⋂ i, s i).Nonempty

Tactic:
h'

Goal state after:
case inr
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
⊢ (∀ (n : ℕ), (dissipate s n).Nonempty) → (⋂ i, s i).Nonempty
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
h₃ : ∀ i ∈ ↑(Tail ⟨term I ho :: ↑l.Tail, hlc⟩), ↑x i = true
h₁ : ∃ i ∈ ↑l.Tail, SwapTrue o (↑x) i ≠ true
⊢ 0 = 1

Tactic:
obtain ⟨i, hi⟩ := h₁

Goal state after:
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
h₃ : ∀ i ∈ ↑(Tail ⟨term I ho :: ↑l.Tail, hlc⟩), ↑x i = true
i : I
hi : i ∈ ↑l.Tail ∧ SwapTrue o (↑x) i ≠ true
⊢ 0 = 1
Module: Mathlib.Topology.Connected.CardComponents

Goal state before:
pp: X : Type u_1
Y : Type u_2
inst✝² : TopologicalSpace X
inst✝¹ : TopologicalSpace Y
f : X → Y
hf₁ : IsOpenMap f
hf₂ : IsClosedMap f
inst✝ : ConnectedSpace Y
y : Y
n : ℕ
U : Fin n → Set X
hU1 : ∀ (i : Fin n), IsClopen (U i)
hU2 : ∀ (i : Fin n), (U i).Nonempty
hU3 : Pairwise (Disjoint on U)
hU4 : ⋃ i, U i = Set.univ
heq : f ⁻¹' {y} = ⋃ i, U i ∩ f ⁻¹' {y}
⊢ ↑n ≤ (f ⁻¹' {y}).encard

Tactic:
heq,

Goal state after:
X : Type u_1
Y : Type u_2
inst✝² : TopologicalSpace X
inst✝¹ : TopologicalSpace Y
f : X → Y
hf₁ : IsOpenMap f
hf₂ : IsClosedMap f
inst✝ : ConnectedSpace Y
y : Y
n : ℕ
U : Fin n → Set X
hU1 : ∀ (i : Fin n), IsClopen (U i)
hU2 : ∀ (i : Fin n), (U i).Nonempty
hU3 : Pairwise (Disjoint on U)
hU4 : ⋃ i, U i = Set.univ
heq : f ⁻¹' {y} = ⋃ i, U i ∩ f ⁻¹' {y}
⊢ ↑n ≤ (⋃ i, U i ∩ f ⁻¹' {y}).encard
Module: Mathlib.Topology.ContinuousMap.BoundedCompactlySupported

Goal state before:
pp: α : Type u_1
γ : Type u_2
inst✝¹ : TopologicalSpace α
inst✝ : NonUnitalNormedRing γ
g : α → γ
hg₁ : Continuous g
hg₂ : HasCompactSupport g
hs : tsupport g = ∅
⊢ ∀ (x y : α), dist (g x) (g y) ≤ 0

Tactic:
by simp [tsupport_eq_empty_iff.mp hs]

Goal state after:
Module: Mathlib.Topology.EMetricSpace.Weak

Goal state before:
pp: α : Type u
t : TopologicalSpace α
m : WeakPseudoEMetricSpace α
r : ℝ≥0∞
hr : 0 < r
⊢ Metric.eball none r = {none}

Tactic:
refine eq_singleton_iff_unique_mem.mpr ⟨Metric.mem_eball.mpr hr, ?_⟩
  intro x
  match x with
  | (_ : α) => simp
  | none => tauto

Goal state after:
Module: Mathlib.Topology.Homotopy.HSpaces

Goal state before:
pp: t : ↑I
⊢ ↑(qRight (t, 0)) = if ↑t ≤ 1 / 2 then 2 * ↑t else 1

Tactic:
simp only [qRight, coe_zero, add_zero, div_one]
  split_ifs
  · rw [Set.projIcc_of_mem _ ((mul_pos_mem_iff zero_lt_two).2 _)]
    refine ⟨t.2.1, ?_⟩
    tauto
  · rw [(Set.projIcc_eq_right _).2]
    · linarith
    · exact zero_lt_one

Goal state after:
Module: Mathlib.Topology.EMetricSpace.PairReduction

Goal state before:
pp: T✝ : Type u_1
inst✝³ : PseudoEMetricSpace T✝
a✝ c✝ : ℝ≥0∞
J✝ : Finset T✝
inst✝² : DecidableEq T✝
T : Type u_1
inst✝¹ : PseudoEMetricSpace T
a c : ℝ≥0∞
J : Finset T
inst✝ : DecidableEq T
ha : 1 < a
hJ : J.Nonempty
⊢ ↑(#((Finset.range #J).biUnion (pairSetSeq J a c))) ≤ a * ↑(#J)

Tactic:
Finset.card_biUnion_le,

Goal state after:
T✝ : Type u_1
inst✝³ : PseudoEMetricSpace T✝
a✝ c✝ : ℝ≥0∞
J✝ : Finset T✝
inst✝² : DecidableEq T✝
T : Type u_1
inst✝¹ : PseudoEMetricSpace T
a c : ℝ≥0∞
J : Finset T
inst✝ : DecidableEq T
ha : 1 < a
hJ : J.Nonempty
⊢ ↑(∑ a_1 ∈ Finset.range #J, #(pairSetSeq J a c a_1)) ≤ a * ↑(#J)
Module: Mathlib.Topology.Instances.CantorSet

Goal state before:
pp: n : ℕ
⊢ preCantorSet n ⊆ Set.Icc 0 1

Tactic:
← preCantorSet_zero

Goal state after:
n : ℕ
⊢ preCantorSet n ⊆ preCantorSet 0
Module: Mathlib.Topology.Instances.CantorSet

Goal state before:
pp: x : ℝ
hx : x ∈ cantorSet
n : ℕ
⊢ (cantorSequence x).get n ∈ cantorSet

Tactic:
induction n with
  | zero => simpa [cantorSequence]
  | succ n ih => exact cantorStep_mem_cantorSet ih

Goal state after:
Module: Mathlib.Topology.Instances.CantorSet

Goal state before:
pp: case refine_2
x : ℝ
x✝ : x ∈ {x | ∃ a, (∀ (i : ℕ), a i ≠ 1) ∧ ofDigits a = x}
a : ℕ → Fin 3
ha : (∀ (i : ℕ), a i ≠ 1) ∧ ofDigits a = x
⊢ ofDigits a ∈ cantorSet

Tactic:
exact ofDigits_zero_two_sequence_mem_cantorSet ha.left

Goal state after:
Module: Mathlib.Topology.List

Goal state before:
pp: α : Type u_1
inst✝ : TopologicalSpace α
x✝ : ℕ
⊢ Tendsto (fun x ↦ x.eraseIdx x✝) (pure []) (𝓝 ([].eraseIdx x✝))

Tactic:
exact tendsto_pure_nhds _ _

Goal state after:
Module: Mathlib.Topology.MetricSpace.Closeds

Goal state before:
pp: α : Type u_1
inst✝ : PseudoEMetricSpace α
s✝ t✝ : Set α
δ : ℝ≥0∞
h✝ :
  (s✝, t✝).1 ⊆ SetRel.preimage {p | edist p.1 p.2 ≤ δ} (s✝, t✝).2 ∧
    (s✝, t✝).2 ⊆ SetRel.image {x | edist x.2 x.1 ≤ δ} (s✝, t✝).1
s t : Set α
h : s ⊆ SetRel.preimage {p | edist p.1 p.2 ≤ δ} t
x : α
hx : x ∈ s
y : α
hy : y ∈ t
hxy : (x, y) ∈ {p | edist p.1 p.2 ≤ δ}
⊢ infEDist x t ≤ δ

Tactic:
exact iInf₂_le_of_le y hy hxy

Goal state after:
Module: Mathlib.Topology.MetricSpace.Kuratowski

Goal state before:
pp: α : Type u
inst✝ : MetricSpace α
x : ℕ → α
a b : α
⊢ ‖embeddingOfSubset x a - embeddingOfSubset x b‖ ≤ dist a b

Tactic:
refine lp.norm_le_of_forall_le dist_nonneg fun n => ?_

Goal state after:
α : Type u
inst✝ : MetricSpace α
x : ℕ → α
a b : α
n : ℕ
⊢ ‖↑(embeddingOfSubset x a - embeddingOfSubset x b) n‖ ≤ dist a b
Module: Mathlib.Topology.MetricSpace.CoveringNumbers

Goal state before:
pp: case refine_1
X : Type u_1
Y : Type u_2
inst✝¹ : PseudoEMetricSpace X
inst✝ : PseudoEMetricSpace Y
A : Set X
ε : ℝ≥0
f : X → Y
hf : Isometry f
hf_inj : InjOn f A
C : Set X
hC_subset : C ⊆ A
hC_cover : IsCover ε A C
this : C ⊆ f ⁻¹' f '' A
⊢ ⨅ (_ : IsCover ε (f '' A) (f '' C)), (f '' C).encard ≤ C.encard

Tactic:
hf.isCover_image_iff

Goal state after:
case refine_1
X : Type u_1
Y : Type u_2
inst✝¹ : PseudoEMetricSpace X
inst✝ : PseudoEMetricSpace Y
A : Set X
ε : ℝ≥0
f : X → Y
hf : Isometry f
hf_inj : InjOn f A
C : Set X
hC_subset : C ⊆ A
hC_cover : IsCover ε A C
this : C ⊆ f ⁻¹' f '' A
⊢ ⨅ (_ : IsCover ε A C), (f '' C).encard ≤ C.encard
Module: Mathlib.Topology.MetricSpace.HolderNorm

Goal state before:
pp: X : Type u_1
Y : Type u_2
inst✝¹ : PseudoEMetricSpace X
inst✝ : PseudoEMetricSpace Y
r : ℝ≥0
c : Y
⊢ nnHolderNorm r (Function.const X c) = 0

Tactic:
rw [← nonpos_iff_eq_zero, ← ENNReal.coe_le_coe, ENNReal.coe_zero, ← eHolderNorm_const X r c]
  exact coe_nnHolderNorm_le_eHolderNorm

Goal state after:
Module: Mathlib.Topology.MetricSpace.HolderNorm

Goal state before:
pp: X : Type u_1
Y : Type u_2
inst✝⁴ : MetricSpace X
inst✝³ : NormedAddCommGroup Y
r : ℝ≥0
f : X → Y
𝕜 : Type u_3
inst✝² : SeminormedRing 𝕜
inst✝¹ : Module 𝕜 Y
inst✝ : NormSMulClass 𝕜 Y
c : 𝕜
hc : ‖c‖₊ ≠ 0
x✝ : MemHolder r (c • f)
h : ℝ≥0
hh : HolderWith h r (c • f)
⊢ HolderWith h r (c • f)

Tactic:
exact hh

Goal state after:
Module: Mathlib.Topology.Order.LowerUpperTopology

Goal state before:
pp: case mp
α : Type u_1
inst✝² : Preorder α
inst✝¹ : TopologicalSpace α
inst✝ : IsLower α
s : Set α
⊢ s ∈ {s | ∃ t, t.Finite ∧ ⋂ i ∈ t, (Ici i)ᶜ = s} → s ∈ (fun f ↦ ⋂₀ f) '' {f | f.Finite ∧ f ⊆ {s | ∃ a, (Ici a)ᶜ = s}}

Tactic:
rintro ⟨F, hF, rfl⟩
    refine ⟨(fun a => (Ici a)ᶜ) '' F, ⟨hF.image _, image_subset_iff.2 fun _ _ => ⟨_, rfl⟩⟩, ?_⟩
    simp only [sInter_image]

Goal state after:
Module: Mathlib.Topology.Order.ScottTopology

Goal state before:
pp: α : Type u_1
inst✝² : Preorder α
inst✝¹ : TopologicalSpace α
s : Set α
inst✝ : IsScott α univ
⊢ IsClosed[inst✝¹] s ↔ IsLowerSet s ∧ DirSupClosed s

Tactic:
rw [← isOpen_compl_iff, isOpen_iff_isUpperSet_and_dirSupInaccOn (D := univ), isUpperSet_compl,
    dirSupInaccOn_univ, dirSupInacc_compl]

Goal state after:
Module: Mathlib.Topology.Order.ScottTopology

Goal state before:
pp: α : Type u_1
inst✝² : Preorder α
inst✝¹ : TopologicalSpace α
a : α
inst✝ : IsScott α univ
⊢ Iic a ⊆ closure[inst✝¹] {a}

Tactic:
rw [← LowerSet.coe_Iic, ← lowerClosure_singleton]
    apply lowerClosure_subset_closure

Goal state after:
Module: Mathlib.Topology.Order.ScottTopology

Goal state before:
pp: α : Type u_1
β : Type u_2
inst✝² : CompleteLinearOrder α
inst✝¹ : TopologicalSpace α
inst✝ : IsUpper α
⊢ inst✝¹ = scott α univ

Tactic:
rw [scott_eq_upper_of_completeLinearOrder]

Goal state after:
α : Type u_1
β : Type u_2
inst✝² : CompleteLinearOrder α
inst✝¹ : TopologicalSpace α
inst✝ : IsUpper α
⊢ inst✝¹ = upper α
Module: Mathlib.Topology.Order.Completion

Goal state before:
pp: case refine_1
α : Type u_1
inst✝⁴ : LinearOrder α
inst✝³ : TopologicalSpace α
inst✝² : OrderTopology α
inst✝¹ : TopologicalSpace (DedekindCut α)
inst✝ : OrderTopology (DedekindCut α)
c : DedekindCut α
this : IsOpen (⋃ a ∈ c.right, Ioi a)
⊢ IsOpen ((fun a ↦ principal a) ⁻¹' Ioi c)

Tactic:
convert this

Goal state after:
α : Type u_1
inst✝⁴ : LinearOrder α
inst✝³ : TopologicalSpace α
inst✝² : OrderTopology α
inst✝¹ : TopologicalSpace (DedekindCut α)
inst✝ : OrderTopology (DedekindCut α)
c : DedekindCut α
this : IsOpen (⋃ a ∈ c.right, Ioi a)
⊢ (fun a ↦ principal a) ⁻¹' Ioi c = ⋃ a ∈ c.right, Ioi a
Module: Mathlib.Topology.Order.Completion

Goal state before:
pp: case refine_2
α : Type u_1
inst✝⁴ : LinearOrder α
inst✝³ : TopologicalSpace α
inst✝² : OrderTopology α
inst✝¹ : TopologicalSpace (DedekindCut α)
inst✝ : OrderTopology (DedekindCut α)
c : DedekindCut α
this : IsOpen (⋃ a ∈ c.left, Iio a)
⊢ IsOpen ((fun a ↦ principal a) ⁻¹' Iio c)

Tactic:
convert this

Goal state after:
α : Type u_1
inst✝⁴ : LinearOrder α
inst✝³ : TopologicalSpace α
inst✝² : OrderTopology α
inst✝¹ : TopologicalSpace (DedekindCut α)
inst✝ : OrderTopology (DedekindCut α)
c : DedekindCut α
this : IsOpen (⋃ a ∈ c.left, Iio a)
⊢ (fun a ↦ principal a) ⁻¹' Iio c = ⋃ a ∈ c.left, Iio a
Module: Mathlib.Topology.MetricSpace.GromovHausdorff

Goal state before:
pp: X : Type u
inst✝⁵ : MetricSpace X
inst✝⁴ : CompactSpace X
inst✝³ : Nonempty X
Y : Type v
inst✝² : MetricSpace Y
inst✝¹ : CompactSpace Y
inst✝ : Nonempty Y
inhabited_h✝ : Inhabited X
inhabited_h : Inhabited Y
p q : NonemptyCompacts ↥(lp (fun n ↦ ℝ) ∞)
hp : ⟦p⟧ = toGHSpace X
hq : ⟦q⟧ = toGHSpace Y
bound : hausdorffDist ↑p ↑q < diam univ + 1 + diam univ
Φ : X → ↥(lp (fun n ↦ ℝ) ∞)
Φisom : Isometry Φ
Φrange : range Φ = ↑p
Ψ : Y → ↥(lp (fun n ↦ ℝ) ∞)
Ψisom : Isometry Ψ
Ψrange : range Ψ = ↑q
I : diam (range Φ ∪ range Ψ) ≤ 2 * diam univ + 1 + 2 * diam univ
f : X ⊕ Y → ↥(lp (fun n ↦ ℝ) ∞) :=
  fun x ↦
    match x with
    | inl y => Φ y
    | inr z => Ψ z
F : (X ⊕ Y) × (X ⊕ Y) → ℝ := fun p ↦ dist (f p.1) (f p.2)
Fgood : F ∈ candidates X Y
Fb : GromovHausdorff.Cb✝ X Y := candidatesBOfCandidates F Fgood
this : hausdorffDist (range (optimalGHInjl X Y)) (range (optimalGHInjr X Y)) ≤ HD Fb
r : ℝ
hr : hausdorffDist ↑p ↑q < r
x : X
⊢ ⨅ y, Fb (inl x, inr y) ≤ r

Tactic:
have : f (inl x) ∈ (p : Set _) := Φrange ▸ (mem_range_self _)

Goal state after:
X : Type u
inst✝⁵ : MetricSpace X
inst✝⁴ : CompactSpace X
inst✝³ : Nonempty X
Y : Type v
inst✝² : MetricSpace Y
inst✝¹ : CompactSpace Y
inst✝ : Nonempty Y
inhabited_h✝ : Inhabited X
inhabited_h : Inhabited Y
p q : NonemptyCompacts ↥(lp (fun n ↦ ℝ) ∞)
hp : ⟦p⟧ = toGHSpace X
hq : ⟦q⟧ = toGHSpace Y
bound : hausdorffDist ↑p ↑q < diam univ + 1 + diam univ
Φ : X → ↥(lp (fun n ↦ ℝ) ∞)
Φisom : Isometry Φ
Φrange : range Φ = ↑p
Ψ : Y → ↥(lp (fun n ↦ ℝ) ∞)
Ψisom : Isometry Ψ
Ψrange : range Ψ = ↑q
I : diam (range Φ ∪ range Ψ) ≤ 2 * diam univ + 1 + 2 * diam univ
f : X ⊕ Y → ↥(lp (fun n ↦ ℝ) ∞) :=
  fun x ↦
    match x with
    | inl y => Φ y
    | inr z => Ψ z
F : (X ⊕ Y) × (X ⊕ Y) → ℝ := fun p ↦ dist (f p.1) (f p.2)
Fgood : F ∈ candidates X Y
Fb : GromovHausdorff.Cb✝ X Y := candidatesBOfCandidates F Fgood
this✝ : hausdorffDist (range (optimalGHInjl X Y)) (range (optimalGHInjr X Y)) ≤ HD Fb
r : ℝ
hr : hausdorffDist ↑p ↑q < r
x : X
this : f (inl x) ∈ ↑p
⊢ ⨅ y, Fb (inl x, inr y) ≤ r
Module: Mathlib.Topology.Partial

Goal state before:
pp: case mp
X : Type u_1
Y : Type u_2
inst✝¹ : TopologicalSpace X
inst✝ : TopologicalSpace Y
f : X →. Y
h : PContinuous f
x : X
y : Y
⊢ y ∈ f x → PTendsto' f (𝓝 x) (𝓝 y)

Tactic:
h'

Goal state after:
case mp
X : Type u_1
Y : Type u_2
inst✝¹ : TopologicalSpace X
inst✝ : TopologicalSpace Y
f : X →. Y
h : PContinuous f
x : X
y : Y
h' : y ∈ f x
⊢ PTendsto' f (𝓝 x) (𝓝 y)
Module: Mathlib.Topology.Order.LawsonTopology

Goal state before:
pp: case e'_2
α : Type u_1
inst✝² : Preorder α
inst✝¹ : TopologicalSpace α
inst✝ : IsLawson α
lawsonBasis_image2 :
  lawsonBasis α =
    image2 (fun x x_1 ↦ ⇑WithLower.toLower ⁻¹' x ∩ ⇑WithScott.toScott ⁻¹' x_1) (IsLower.lowerBasis (WithLower α))
      {U | IsOpen[scott α univ] U}
⊢ lower α ⊓ scott α univ =
    induced (⇑WithLower.toLower) WithLower.instTopologicalSpace ⊓
      induced (⇑WithScott.toScott) WithScott.instTopologicalSpace

Tactic:
apply (congrArg₂ min _) _

Goal state after:
α : Type u_1
inst✝² : Preorder α
inst✝¹ : TopologicalSpace α
inst✝ : IsLawson α
lawsonBasis_image2 :
  lawsonBasis α =
    image2 (fun x x_1 ↦ ⇑WithLower.toLower ⁻¹' x ∩ ⇑WithScott.toScott ⁻¹' x_1) (IsLower.lowerBasis (WithLower α))
      {U | IsOpen[scott α univ] U}
⊢ lower α = induced (⇑WithLower.toLower) WithLower.instTopologicalSpace

α : Type u_1
inst✝² : Preorder α
inst✝¹ : TopologicalSpace α
inst✝ : IsLawson α
lawsonBasis_image2 :
  lawsonBasis α =
    image2 (fun x x_1 ↦ ⇑WithLower.toLower ⁻¹' x ∩ ⇑WithScott.toScott ⁻¹' x_1) (IsLower.lowerBasis (WithLower α))
      {U | IsOpen[scott α univ] U}
⊢ scott α univ = induced (⇑WithScott.toScott) WithScott.instTopologicalSpace
Module: Mathlib.Topology.Separation.LinearUpperLowerSetTopology

Goal state before:
pp: α : Type u_1
inst✝² : TopologicalSpace α
inst✝¹ : LinearOrder α
inst✝ : Topology.IsUpperSet α
t : Set α
hcst : Disjoint (closure ∅) t
hsct : Disjoint ∅ (closure t)
⊢ Disjoint (nhdsSet ∅) (nhdsSet t)

Tactic:
case =>

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

Goal state before:
pp: α : Type u_1
inst✝² : TopologicalSpace α
inst✝¹ : LinearOrder α
inst✝ : Topology.IsUpperSet α
s : Set α
a : α
ha : a ∈ s
hcst : Disjoint (closure s) ∅
hsct : Disjoint s (closure ∅)
⊢ Disjoint (nhdsSet s) (nhdsSet ∅)

Tactic:
case =>

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

Goal state before:
pp: X : Type u_1
inst✝ : TopologicalSpace X
h : ∀ (s : Set X), IsClosed[inst✝] s → ∃ f, s = ⇑f ⁻¹' {0} ∧ ∀ (x : X), f x ∈ Icc 0 1
s t : Set X
hs : IsClosed[inst✝] s
ht : IsClosed[inst✝] t
hst : Disjoint s t
⊢ SeparatedNhds s t

Tactic:
by
        -- pick `f, g` such that `s = f ⁻¹' {0}` and `t = g ⁻¹' {0}`, and then the function
        -- `f / (f  + g)` separates `s` and `t`.
        obtain ⟨f, hf, hfr⟩ := h s hs
        obtain ⟨g, hg, hgr⟩ := h t ht
        have hsn : SeparatedNhds {(0 : ℝ)} {1} :=
          SeparatedNhds.of_finite (finite_singleton _) (finite_singleton _)
          (disjoint_singleton.2 zero_ne_one)
        have hfg (x : X) : f x + g x ≠ 0 := by
          simp_all only [preimage, mem_singleton_iff]
          by_cases! hfx : f x = 0
          · simpa [hfx] using hst.notMem_of_mem_left hfx
          · positivity [(hgr x).1, (hfr x).1]
        have hp : s = (fun a => f a / (f a + g a)) ⁻¹' {0} := by simp_all [preimage]
        have : t = (fun a => f a / (f a + g a)) ⁻¹' {1} := by simp_all [preimage, div_eq_one_iff_eq]
        rw [hp, this]
        exact hsn.preimage (f.continuous.div₀ (f.continuous.add g.continuous) hfg)

Goal state after:
Module: Mathlib.Topology.MetricSpace.GromovHausdorff

Goal state before:
pp: δ : ℝ
δpos : δ > 0
⊢ ∃ β x F, ∀ (x y : GHSpace), F x = F y → dist x y ≤ δ

Tactic:
let ε := 2 / 5 * δ

Goal state after:
δ : ℝ
δpos : δ > 0
ε : ℝ := 2 / 5 * δ
⊢ ∃ β x F, ∀ (x y : GHSpace), F x = F y → dist x y ≤ δ
Module: Mathlib.Topology.MetricSpace.GromovHausdorff

Goal state before:
pp: case refine_2
δ : ℝ
δpos : δ > 0
ε : ℝ := 2 / 5 * δ
εpos : 0 < ε
s : (p : GHSpace) → Set p.Rep
hs : ∀ (p : GHSpace), (s p).Finite ∧ univ ⊆ ⋃ x ∈ s p, ball x ε
N : GHSpace → ℕ := fun p ↦ Nat.card ↑(s p)
E : (p : GHSpace) → ↑(s p) ≃ Fin (Nat.card ↑(s p)) := fun p ↦ Finite.equivFin ↑(s p)
F : GHSpace → (n : ℕ) × (Fin n → Fin n → ℤ) := fun p ↦ ⟨N p, fun a b ↦ ⌊ε⁻¹ * dist ((E p).symm a) ((E p).symm b)⌋⟩
p q : GHSpace
hpq : F p = F q
Npq : N p = N q
Ψ : ↑(s p) → ↑(s q) := fun x ↦ (E q).symm (Fin.cast Npq ((E p) x))
Φ : ↑(s p) → q.Rep := fun x ↦ ↑(Ψ x)
⊢ ∀ (x : q.Rep), ∃ y, dist x (Φ y) ≤ ε

pp: case refine_3
δ : ℝ
δpos : δ > 0
ε : ℝ := 2 / 5 * δ
εpos : 0 < ε
s : (p : GHSpace) → Set p.Rep
hs : ∀ (p : GHSpace), (s p).Finite ∧ univ ⊆ ⋃ x ∈ s p, ball x ε
N : GHSpace → ℕ := fun p ↦ Nat.card ↑(s p)
E : (p : GHSpace) → ↑(s p) ≃ Fin (Nat.card ↑(s p)) := fun p ↦ Finite.equivFin ↑(s p)
F : GHSpace → (n : ℕ) × (Fin n → Fin n → ℤ) := fun p ↦ ⟨N p, fun a b ↦ ⌊ε⁻¹ * dist ((E p).symm a) ((E p).symm b)⌋⟩
p q : GHSpace
hpq : F p = F q
Npq : N p = N q
Ψ : ↑(s p) → ↑(s q) := fun x ↦ (E q).symm (Fin.cast Npq ((E p) x))
Φ : ↑(s p) → q.Rep := fun x ↦ ↑(Ψ x)
⊢ ∀ (x y : ↑(s p)), |dist x y - dist (Φ x) (Φ y)| ≤ ε

Tactic:
· show ∀ x : q.Rep, ∃ z : s p, dist x (Φ z) ≤ ε
      -- by construction, `s q` is `ε`-dense, and it is the range of `Φ`
      intro x
      have : x ∈ ⋃ y ∈ s q, ball y ε := (hs q).2 (mem_univ _)
      obtain ⟨y, ys, hy⟩ := mem_iUnion₂.1 this
      let i : ℕ := E q ⟨y, ys⟩
      let hi := ((E q) ⟨y, ys⟩).is_lt
      have ihi_eq : (⟨i, hi⟩ : Fin (N q)) = (E q) ⟨y, ys⟩ := by rw [Fin.ext_iff, Fin.val_mk]
      have hiq : i < N q := hi
      have hip : i < N p := by rwa [Npq.symm] at hiq
      let z := (E p).symm ⟨i, hip⟩
      use z
      have C1 : (E p) z = ⟨i, hip⟩ := (E p).apply_symm_apply ⟨i, hip⟩
      have C2 : Fin.cast Npq ⟨i, hip⟩ = ⟨i, hi⟩ := rfl
      have C3 : (E q).symm ⟨i, hi⟩ = ⟨y, ys⟩ := by
        rw [ihi_eq]; exact (E q).symm_apply_apply ⟨y, ys⟩
      have : Φ z = y := by simp only [Φ, Ψ]; rw [C1, C2, C3]
      rw [this]
      exact hy.le

Goal state after:
case refine_3
δ : ℝ
δpos : δ > 0
ε : ℝ := 2 / 5 * δ
εpos : 0 < ε
s : (p : GHSpace) → Set p.Rep
hs : ∀ (p : GHSpace), (s p).Finite ∧ univ ⊆ ⋃ x ∈ s p, ball x ε
N : GHSpace → ℕ := fun p ↦ Nat.card ↑(s p)
E : (p : GHSpace) → ↑(s p) ≃ Fin (Nat.card ↑(s p)) := fun p ↦ Finite.equivFin ↑(s p)
F : GHSpace → (n : ℕ) × (Fin n → Fin n → ℤ) := fun p ↦ ⟨N p, fun a b ↦ ⌊ε⁻¹ * dist ((E p).symm a) ((E p).symm b)⌋⟩
p q : GHSpace
hpq : F p = F q
Npq : N p = N q
Ψ : ↑(s p) → ↑(s q) := fun x ↦ (E q).symm (Fin.cast Npq ((E p) x))
Φ : ↑(s p) → q.Rep := fun x ↦ ↑(Ψ x)
⊢ ∀ (x y : ↑(s p)), |dist x y - dist (Φ x) (Φ y)| ≤ ε
Module: Mathlib.Topology.Sheaves.Alexandrov

Goal state before:
pp: X✝ : Type v
inst✝⁶ : TopologicalSpace X✝
inst✝⁵ : Preorder X✝
inst✝⁴ : Topology.IsUpperSet X✝
C : Type u
inst✝³ : Category.{v, u} C
inst✝² : HasLimits C
F✝ : X✝ ⥤ C
X : TopCat
inst✝¹ : Preorder ↑X
inst✝ : Topology.IsUpperSet ↑X
F : ↑X ⥤ C
α : Type v
Us : α → Opens ↑X
S : Cone ((ObjectProperty.ι fun V ↦ ∃ i, V ≤ Us i).op ⋙ principalsKanExtension F)
V : Opens ↑X
i : α
hV : V ≤ Us i
left✝ : Discrete PUnit.{1}
x : ↑X
f : (fromPUnit (Opposite.op V)).obj left✝ ⟶ (principals ↑X).obj x
⊢ S.π.app (Opposite.op { obj := principalOpen x, property := ⋯ }) ≫
      limit.π (generator (principalOpen x) ⋙ F)
        { left := { as := PUnit.unit }, right := x, hom := 𝟙 (Opposite.op (principalOpen x)) } =
    S.π.app (Opposite.op { obj := V, property := ⋯ }) ≫
      limit.π (StructuredArrow.proj (Opposite.op V) (principals ↑X) ⋙ F) { left := left✝, right := x, hom := f }

Tactic:
have e : principalOpen x ≤ V := f.unop.le

Goal state after:
X✝ : Type v
inst✝⁶ : TopologicalSpace X✝
inst✝⁵ : Preorder X✝
inst✝⁴ : Topology.IsUpperSet X✝
C : Type u
inst✝³ : Category.{v, u} C
inst✝² : HasLimits C
F✝ : X✝ ⥤ C
X : TopCat
inst✝¹ : Preorder ↑X
inst✝ : Topology.IsUpperSet ↑X
F : ↑X ⥤ C
α : Type v
Us : α → Opens ↑X
S : Cone ((ObjectProperty.ι fun V ↦ ∃ i, V ≤ Us i).op ⋙ principalsKanExtension F)
V : Opens ↑X
i : α
hV : V ≤ Us i
left✝ : Discrete PUnit.{1}
x : ↑X
f : (fromPUnit (Opposite.op V)).obj left✝ ⟶ (principals ↑X).obj x
e : principalOpen x ≤ V
⊢ S.π.app (Opposite.op { obj := principalOpen x, property := ⋯ }) ≫
      limit.π (generator (principalOpen x) ⋙ F)
        { left := { as := PUnit.unit }, right := x, hom := 𝟙 (Opposite.op (principalOpen x)) } =
    S.π.app (Opposite.op { obj := V, property := ⋯ }) ≫
      limit.π (StructuredArrow.proj (Opposite.op V) (principals ↑X) ⋙ F) { left := left✝, right := x, hom := f }
Module: Mathlib.Topology.Sheaves.SheafCondition.EqualizerProducts

Goal state before:
pp: C : Type u
inst✝¹ : Category.{v, u} C
inst✝ : HasProducts C
X : TopCat
F : Presheaf C X
ι : Type v'
U : ι → Opens ↑X
G : Presheaf C X
α : F ≅ G
⊢ (X_1 : WalkingParallelPair) → (diagram F U).obj X_1 ≅ (diagram G U).obj X_1

Tactic:
rintro ⟨⟩

Goal state after:
case zero
C : Type u
inst✝¹ : Category.{v, u} C
inst✝ : HasProducts C
X : TopCat
F : Presheaf C X
ι : Type v'
U : ι → Opens ↑X
G : Presheaf C X
α : F ≅ G
⊢ (diagram F U).obj WalkingParallelPair.zero ≅ (diagram G U).obj WalkingParallelPair.zero

case one
C : Type u
inst✝¹ : Category.{v, u} C
inst✝ : HasProducts C
X : TopCat
F : Presheaf C X
ι : Type v'
U : ι → Opens ↑X
G : Presheaf C X
α : F ≅ G
⊢ (diagram F U).obj WalkingParallelPair.one ≅ (diagram G U).obj WalkingParallelPair.one
Module: Mathlib.Topology.Sheaves.SheafCondition.EqualizerProducts

Goal state before:
pp: case op.op.single.pair.left
C : Type u
inst✝¹ : Category.{v, u} C
inst✝ : HasProducts C
X : TopCat
F : Presheaf C X
ι : Type v'
U : ι → Opens ↑X
c : Cone (SheafConditionEqualizerProducts.diagram F U)
i j : ι
h :
  c.π.app WalkingParallelPair.one =
    Fork.ι c ≫ Pi.lift fun p ↦ Pi.π (fun i ↦ F.obj (op (U i))) p.1 ≫ F.map ((U p.1).infLELeft (U p.2)).op
h' :
  c.π.app WalkingParallelPair.one ≫ Pi.π (fun p ↦ F.obj (op (U p.1 ⊓ U p.2))) (i, j) =
    (Fork.ι c ≫ Pi.lift fun p ↦ Pi.π (fun i ↦ F.obj (op (U i))) p.1 ≫ F.map ((U p.1).infLELeft (U p.2)).op) ≫
      Pi.π (fun p ↦ F.obj (op (U p.1 ⊓ U p.2))) (i, j)
⊢ c.π.app WalkingParallelPair.one ≫ Pi.π (fun p ↦ F.obj (op (U p.1 ⊓ U p.2))) (i, j) =
    Fork.ι c ≫ Pi.π (fun i ↦ F.obj (op (U i))) i ≫ F.map (homOfLE ⋯).op

Tactic:
h'

Goal state after:
case op.op.single.pair.left
C : Type u
inst✝¹ : Category.{v, u} C
inst✝ : HasProducts C
X : TopCat
F : Presheaf C X
ι : Type v'
U : ι → Opens ↑X
c : Cone (SheafConditionEqualizerProducts.diagram F U)
i j : ι
h :
  c.π.app WalkingParallelPair.one =
    Fork.ι c ≫ Pi.lift fun p ↦ Pi.π (fun i ↦ F.obj (op (U i))) p.1 ≫ F.map ((U p.1).infLELeft (U p.2)).op
h' :
  c.π.app WalkingParallelPair.one ≫ Pi.π (fun p ↦ F.obj (op (U p.1 ⊓ U p.2))) (i, j) =
    (Fork.ι c ≫ Pi.lift fun p ↦ Pi.π (fun i ↦ F.obj (op (U i))) p.1 ≫ F.map ((U p.1).infLELeft (U p.2)).op) ≫
      Pi.π (fun p ↦ F.obj (op (U p.1 ⊓ U p.2))) (i, j)
⊢ (Fork.ι c ≫ Pi.lift fun p ↦ Pi.π (fun i ↦ F.obj (op (U i))) p.1 ≫ F.map ((U p.1).infLELeft (U p.2)).op) ≫
      Pi.π (fun p ↦ F.obj (op (U p.1 ⊓ U p.2))) (i, j) =
    Fork.ι c ≫ Pi.π (fun i ↦ F.obj (op (U i))) i ≫ F.map (homOfLE ⋯).op