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

Goal state before:
pp: case neg.inr
α : Type u_1
β : Type u_2
inst✝² : TopologicalSpace α
inst✝¹ : TopologicalSpace β
s : Set α
p : α → Prop
f g : α → β
inst✝ : (a : α) → Decidable (p a)
hpf : ∀ a ∈ s ∩ frontier {a | p a}, Tendsto f (𝓝[s ∩ {a | p a}] a) (𝓝 (if p a then f a else g a))
hpg : ∀ a ∈ s ∩ frontier {a | p a}, Tendsto g (𝓝[s ∩ {a | ¬p a}] a) (𝓝 (if p a then f a else g a))
hf : ContinuousOn f (s ∩ {a | p a})
hg : ContinuousOn g (s ∩ {a | ¬p a})
x : α
hx' : x ∉ frontier {a | p a}
hx : x ∈ s ∩ {a | p a}ᶜ
⊢ ContinuousWithinAt (fun a ↦ if p a then f a else g a) (s ∩ {a | p a} ∪ s ∩ {a | p a}ᶜ) x

Tactic:
apply ContinuousWithinAt.union

Goal state after:
case neg.inr.hs
α : Type u_1
β : Type u_2
inst✝² : TopologicalSpace α
inst✝¹ : TopologicalSpace β
s : Set α
p : α → Prop
f g : α → β
inst✝ : (a : α) → Decidable (p a)
hpf : ∀ a ∈ s ∩ frontier {a | p a}, Tendsto f (𝓝[s ∩ {a | p a}] a) (𝓝 (if p a then f a else g a))
hpg : ∀ a ∈ s ∩ frontier {a | p a}, Tendsto g (𝓝[s ∩ {a | ¬p a}] a) (𝓝 (if p a then f a else g a))
hf : ContinuousOn f (s ∩ {a | p a})
hg : ContinuousOn g (s ∩ {a | ¬p a})
x : α
hx' : x ∉ frontier {a | p a}
hx : x ∈ s ∩ {a | p a}ᶜ
⊢ ContinuousWithinAt (fun a ↦ if p a then f a else g a) (s ∩ {a | p a}) x

case neg.inr.ht
α : Type u_1
β : Type u_2
inst✝² : TopologicalSpace α
inst✝¹ : TopologicalSpace β
s : Set α
p : α → Prop
f g : α → β
inst✝ : (a : α) → Decidable (p a)
hpf : ∀ a ∈ s ∩ frontier {a | p a}, Tendsto f (𝓝[s ∩ {a | p a}] a) (𝓝 (if p a then f a else g a))
hpg : ∀ a ∈ s ∩ frontier {a | p a}, Tendsto g (𝓝[s ∩ {a | ¬p a}] a) (𝓝 (if p a then f a else g a))
hf : ContinuousOn f (s ∩ {a | p a})
hg : ContinuousOn g (s ∩ {a | ¬p a})
x : α
hx' : x ∉ frontier {a | p a}
hx : x ∈ s ∩ {a | p a}ᶜ
⊢ ContinuousWithinAt (fun a ↦ if p a then f a else g a) (s ∩ {a | p a}ᶜ) x
Module: Mathlib.Topology.Compactness.Compact

Goal state before:
pp: ι : Type u_1
X : ι → Type u_2
inst✝ : (i : ι) → TopologicalSpace (X i)
s : (i : ι) → Set (X i)
h : ∀ (i : ι), IsCompact (s i)
⊢ IsCompact (univ.pi s)

Tactic:
convert! isCompact_pi_infinite h
  simp only [← mem_univ_pi, ofPred_mem_eq]

Goal state after:
Module: Mathlib.Topology.Irreducible

Goal state before:
pp: case refine_1
X : Type u_1
Y : Type u_2
inst✝¹ : TopologicalSpace X
inst✝ : TopologicalSpace Y
s : Set X
H : IsPreirreducible s
f : X → Y
hf : ContinuousOn f s
u v : Set Y
hu : IsOpen[inst✝] u
hv : IsOpen[inst✝] v
x✝ : X
hx : x✝ ∈ s
hxu : x✝ ∈ f ⁻¹' u
y : X
hy : y ∈ s
hyv : y ∈ f ⁻¹' v
u' : Set X
hu' : IsOpen[inst✝¹] u'
u'_eq : f ⁻¹' u ∩ s = u' ∩ s
v' : Set X
hv' : IsOpen[inst✝¹] v'
v'_eq : f ⁻¹' v ∩ s = v' ∩ s
this : (f ⁻¹' u ∩ s).Nonempty → (f ⁻¹' v ∩ s).Nonempty → (s ∩ (u' ∩ v')).Nonempty
x : X
hxs : x ∈ s
hxu' : x ∈ u'
hxv' : x ∈ v'
⊢ f x ∈ u

Tactic:
rw [← mem_preimage]

Goal state after:
case refine_1
X : Type u_1
Y : Type u_2
inst✝¹ : TopologicalSpace X
inst✝ : TopologicalSpace Y
s : Set X
H : IsPreirreducible s
f : X → Y
hf : ContinuousOn f s
u v : Set Y
hu : IsOpen[inst✝] u
hv : IsOpen[inst✝] v
x✝ : X
hx : x✝ ∈ s
hxu : x✝ ∈ f ⁻¹' u
y : X
hy : y ∈ s
hyv : y ∈ f ⁻¹' v
u' : Set X
hu' : IsOpen[inst✝¹] u'
u'_eq : f ⁻¹' u ∩ s = u' ∩ s
v' : Set X
hv' : IsOpen[inst✝¹] v'
v'_eq : f ⁻¹' v ∩ s = v' ∩ s
this : (f ⁻¹' u ∩ s).Nonempty → (f ⁻¹' v ∩ s).Nonempty → (s ∩ (u' ∩ v')).Nonempty
x : X
hxs : x ∈ s
hxu' : x ∈ u'
hxv' : x ∈ v'
⊢ x ∈ f ⁻¹' u
Module: Mathlib.Topology.Separation.Basic

Goal state before:
pp: X : Type u_1
inst✝¹ : TopologicalSpace X
inst✝ : T0Space X
s : Finset X
ihs : ∀ t ⊂ s, (↑t).Nonempty → IsOpen[inst✝¹] ↑t → ∃ x ∈ ↑t, IsOpen[inst✝¹] {x}
hne : (↑s).Nonempty
ho : IsOpen[inst✝¹] ↑s
ht : ¬∃ t ⊂ s, t.Nonempty ∧ IsOpen[inst✝¹] ↑t
⊢ ∀ t ⊆ ↑s, t.Nonempty → IsOpen[inst✝¹] t → t = ↑s

Tactic:
refine fun t hts htne hto => of_not_not fun hts' => ht ?_

Goal state after:
X : Type u_1
inst✝¹ : TopologicalSpace X
inst✝ : T0Space X
s : Finset X
ihs : ∀ t ⊂ s, (↑t).Nonempty → IsOpen[inst✝¹] ↑t → ∃ x ∈ ↑t, IsOpen[inst✝¹] {x}
hne : (↑s).Nonempty
ho : IsOpen[inst✝¹] ↑s
ht : ¬∃ t ⊂ s, t.Nonempty ∧ IsOpen[inst✝¹] ↑t
t : Set X
hts : t ⊆ ↑s
htne : t.Nonempty
hto : IsOpen[inst✝¹] t
hts' : ¬t = ↑s
⊢ ∃ t ⊂ s, t.Nonempty ∧ IsOpen[inst✝¹] ↑t
Module: Mathlib.Topology.Separation.Basic

Goal state before:
pp: X : Type u_1
inst✝¹ : TopologicalSpace X
inst✝ : T0Space X
s : Finset X
ihs : ∀ t ⊂ s, (↑t).Nonempty → IsOpen[inst✝¹] ↑t → ∃ x ∈ ↑t, IsOpen[inst✝¹] {x}
hne : (↑s).Nonempty
ho : IsOpen[inst✝¹] ↑s
ht : ¬∃ t ⊂ s, t.Nonempty ∧ IsOpen[inst✝¹] ↑t
t : Finset X
hts : ↑t ⊆ ↑s
htne : (↑t).Nonempty
hto : IsOpen[inst✝¹] ↑t
hts' : ¬↑t = ↑s
⊢ ∃ t ⊂ s, t.Nonempty ∧ IsOpen[inst✝¹] ↑t

Tactic:
exact ⟨t, ssubset_iff_subset_ne.2 ⟨hts, mt Finset.coe_inj.2 hts'⟩, htne, hto⟩

Goal state after:
Module: Mathlib.Topology.Irreducible

Goal state before:
pp: case refine_2
X : Type u_1
Y : Type u_2
inst✝¹ : TopologicalSpace X
inst✝ : TopologicalSpace Y
s : Set X
H : IsPreirreducible s
f : X → Y
hf : ContinuousOn f s
u v : Set Y
hu : IsOpen[inst✝] u
hv : IsOpen[inst✝] v
x✝ : X
hx : x✝ ∈ s
hxu : x✝ ∈ f ⁻¹' u
y : X
hy : y ∈ s
hyv : y ∈ f ⁻¹' v
u' : Set X
hu' : IsOpen[inst✝¹] u'
u'_eq : f ⁻¹' u ∩ s = u' ∩ s
v' : Set X
hv' : IsOpen[inst✝¹] v'
v'_eq : f ⁻¹' v ∩ s = v' ∩ s
this : (f ⁻¹' u ∩ s).Nonempty → (f ⁻¹' v ∩ s).Nonempty → (s ∩ (u' ∩ v')).Nonempty
x : X
hxs : x ∈ s
hxu' : x ∈ u'
hxv' : x ∈ v'
⊢ f x ∈ v

Tactic:
rw [← mem_preimage]

Goal state after:
case refine_2
X : Type u_1
Y : Type u_2
inst✝¹ : TopologicalSpace X
inst✝ : TopologicalSpace Y
s : Set X
H : IsPreirreducible s
f : X → Y
hf : ContinuousOn f s
u v : Set Y
hu : IsOpen[inst✝] u
hv : IsOpen[inst✝] v
x✝ : X
hx : x✝ ∈ s
hxu : x✝ ∈ f ⁻¹' u
y : X
hy : y ∈ s
hyv : y ∈ f ⁻¹' v
u' : Set X
hu' : IsOpen[inst✝¹] u'
u'_eq : f ⁻¹' u ∩ s = u' ∩ s
v' : Set X
hv' : IsOpen[inst✝¹] v'
v'_eq : f ⁻¹' v ∩ s = v' ∩ s
this : (f ⁻¹' u ∩ s).Nonempty → (f ⁻¹' v ∩ s).Nonempty → (s ∩ (u' ∩ v')).Nonempty
x : X
hxs : x ∈ s
hxu' : x ∈ u'
hxv' : x ∈ v'
⊢ x ∈ f ⁻¹' v
Module: Mathlib.Topology.Irreducible

Goal state before:
pp: case h₂.h
X : Type u_1
inst✝ : TopologicalSpace X
hX : (irreducibleComponents X).Finite
Z : Set X
hZ : Z ∈ irreducibleComponents X
h : (⋃₀ (irreducibleComponents X \ {Z}))ᶜ ⊆ Z
⊢ (Z ∩ (⋃₀ (irreducibleComponents X \ {Z}))ᶜ).Nonempty

Tactic:
Set.inter_compl_nonempty_iff

Goal state after:
case h₂.h
X : Type u_1
inst✝ : TopologicalSpace X
hX : (irreducibleComponents X).Finite
Z : Set X
hZ : Z ∈ irreducibleComponents X
h : (⋃₀ (irreducibleComponents X \ {Z}))ᶜ ⊆ Z
⊢ ¬Z ⊆ ⋃₀ (irreducibleComponents X \ {Z})
Module: Mathlib.Topology.Irreducible

Goal state before:
pp: X : Type u_1
Y : Type u_2
inst✝¹ : TopologicalSpace X
inst✝ : TopologicalSpace Y
V : Set Y
hV : IsPreirreducible V
f : X → Y
hf' : IsOpenMap f
hf'' : ∀ (x : Y), IsPreirreducible (f ⁻¹' {x})
⊢ IsPreirreducible (f ⁻¹' V)

Tactic:
by
  refine hV.preimage_of_dense_isPreirreducible_fiber f hf' ?_
  simp [hf'', subset_closure]

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

Goal state before:
pp: X : Type u_1
Y : Type u_2
inst✝ : TopologicalSpace X
⊢ T2Space (T2Quotient X)

Tactic:
by
  rw [t2Space_iff]
  rintro ⟨x⟩ ⟨y⟩ (h : ¬ T2Quotient.mk x = T2Quotient.mk y)
  obtain ⟨s, hs, hsxy⟩ : ∃ s, T2Space (Quotient s) ∧ Quotient.mk s x ≠ Quotient.mk s y := by
    simpa [T2Quotient.mk_eq, Quotient.eq] using h
  exact separated_by_continuous (continuous_map_sInf (by exact hs)) hsxy

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

Goal state before:
pp: case refine_3
X : Type u_1
Y : Type u_2
inst✝³ : TopologicalSpace X
inst✝² : T1Space X
inst✝¹ : DecidableEq X
inst✝ : TopologicalSpace Y
f : X → Y
s : Set X
x : X
y : Y
x✝ : x ∈ s
⊢ ContinuousWithinAt (update f x y) s x ↔ Tendsto f (𝓝[s \ {x}] x) (𝓝 y)

Tactic:
· exact continuousWithinAt_update_same

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

Goal state before:
pp: X : Type u_1
inst✝¹ : TopologicalSpace X
inst✝ : T2Space X
S : Set X
⊢ S.Nonempty ∧ S.Subsingleton ↔ ∃ x, S = {x}

Tactic:
exists_eq_singleton_iff_nonempty_subsingleton

Goal state after:
X : Type u_1
inst✝¹ : TopologicalSpace X
inst✝ : T2Space X
S : Set X
⊢ S.Nonempty ∧ S.Subsingleton ↔ S.Nonempty ∧ S.Subsingleton
Module: Mathlib.Topology.DiscreteSubset

Goal state before:
pp: X : Type u_1
inst✝ : TopologicalSpace X
s K : Set X
hK : IsCompact K
hs : s ∈ codiscreteWithin K
⊢ (K \ s).Finite

Tactic:
by
  rw [mem_codiscreteWithin_accPt] at hs
  contrapose! hs
  exact Set.Infinite.exists_accPt_of_subset_isCompact hs hK (sep_subset _ _)

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

Goal state before:
pp: X : Type u_1
inst✝¹ : TopologicalSpace X
inst✝ : R1Space X
x y : X
h : ¬Inseparable x y
⊢ ∃ u v, IsOpen[inst✝¹] u ∧ IsOpen[inst✝¹] v ∧ x ∈ u ∧ y ∈ v ∧ Disjoint u v

Tactic:
rw [← disjoint_nhds_nhds_iff_not_inseparable,
    (nhds_basis_opens x).disjoint_iff (nhds_basis_opens y)] at h

Goal state after:
X : Type u_1
inst✝¹ : TopologicalSpace X
inst✝ : R1Space X
x y : X
h : ∃ i, (x ∈ i ∧ IsOpen[inst✝¹] i) ∧ ∃ i', (y ∈ i' ∧ IsOpen[inst✝¹] i') ∧ Disjoint i i'
⊢ ∃ u v, IsOpen[inst✝¹] u ∧ IsOpen[inst✝¹] v ∧ x ∈ u ∧ y ∈ v ∧ Disjoint u v
Module: Mathlib.Topology.Connected.LocallyConnected

Goal state before:
pp: α : Type u
inst✝¹ : TopologicalSpace α
inst✝ : LocallyConnectedSpace α
x : α
⊢ ∀ (i : Set α), IsOpen[inst✝¹] i ∧ x ∈ i ∧ IsConnected i ↔ i ∈ {s | IsOpen[inst✝¹] s ∧ IsPreconnected s} ∧ x ∈ i

Tactic:
grind [IsConnected, Set.Nonempty]

Goal state after:
Module: Mathlib.Topology.Connected.LocallyConnected

Goal state before:
pp: α : Type u
inst✝ : TopologicalSpace α
h : TopologicalSpace.IsTopologicalBasis {s | IsOpen[inst✝] s ∧ IsPreconnected s}
x✝ : α
⊢ ∀ (i : Set α), i ∈ {s | IsOpen[inst✝] s ∧ IsPreconnected s} ∧ x✝ ∈ i ↔ IsOpen[inst✝] i ∧ x✝ ∈ i ∧ IsConnected i

Tactic:
grind [IsConnected, Set.Nonempty]

Goal state after:
Module: Mathlib.Topology.Connected.Clopen

Goal state before:
pp: X : Type u_3
inst✝ : TopologicalSpace X
u v : Set X
hu : IsOpen[inst✝] u
huv : Disjoint (frontier u) v
⊢ v ↓∩ closure[inst✝] u = v ↓∩ u

Tactic:
apply image_val_injective

Goal state after:
X : Type u_3
inst✝ : TopologicalSpace X
u v : Set X
hu : IsOpen[inst✝] u
huv : Disjoint (frontier u) v
⊢ Subtype.val '' v ↓∩ closure[inst✝] u = Subtype.val '' v ↓∩ u
Module: Mathlib.Topology.Connected.Clopen

Goal state before:
pp: α : Type u
inst✝ : TopologicalSpace α
s : Set α
⊢ IsPreconnected s ↔
    ∀ (u v : Set α), IsClosed[inst✝] u → IsClosed[inst✝] v → s ⊆ u ∪ v → s ∩ (u ∩ v) = ∅ → s ⊆ u ∨ s ⊆ v

Tactic:
by
  constructor <;> intro h
  · intro u v hu hv hs huv
    rw [isPreconnected_closed_iff] at h
    specialize h u v hu hv hs
    contrapose! huv
    simp only [not_subset] at huv
    rcases huv with ⟨⟨x, hxs, hxu⟩, ⟨y, hys, hyv⟩⟩
    have hxv : x ∈ v := or_iff_not_imp_left.mp (hs hxs) hxu
    have hyu : y ∈ u := or_iff_not_imp_right.mp (hs hys) hyv
    exact h ⟨y, hys, hyu⟩ ⟨x, hxs, hxv⟩
  · rw [isPreconnected_closed_iff]
    intro u v hu hv hs hsu hsv
    by_contra H
    specialize h u v hu hv hs (Set.not_nonempty_iff_eq_empty.mp H)
    apply H
    rcases h with h | h
    · rcases hsv with ⟨x, hxs, hxv⟩
      exact ⟨x, hxs, ⟨h hxs, hxv⟩⟩
    · rcases hsu with ⟨x, hxs, hxu⟩
      exact ⟨x, hxs, ⟨hxu, h hxs⟩⟩

Goal state after:
Module: Mathlib.Topology.DenseEmbedding

Goal state before:
pp: α : Type u_1
β : Type u_2
γ : Type u_3
inst✝³ : TopologicalSpace α
inst✝² : TopologicalSpace β
i : α → β
inst✝¹ : TopologicalSpace γ
inst✝ : T3Space γ
b : β
f : α → γ
di : IsDenseInducing i
hf : ∀ᶠ (x : β) in 𝓝 b, ∃ c, Tendsto f (comap i (𝓝 x)) (𝓝 c)
φ : β → γ := di.extend f
this : ∀ (b : β), (comap i (𝓝 b)).NeBot
V' : Set γ
V'_in : V' ∈ 𝓝 (φ b)
V'_closed : IsClosed[inst✝¹] V'
V₁ : Set β := {x | Tendsto f (comap i (𝓝 x)) (𝓝 (φ x))}
⊢ φ ⁻¹' V' ∈ 𝓝 b

Tactic:
have V₁_in : V₁ ∈ 𝓝 b := by
    filter_upwards [hf]
    rintro x ⟨c, hc⟩
    rwa [← di.extend_eq_of_tendsto hc] at hc

Goal state after:
α : Type u_1
β : Type u_2
γ : Type u_3
inst✝³ : TopologicalSpace α
inst✝² : TopologicalSpace β
i : α → β
inst✝¹ : TopologicalSpace γ
inst✝ : T3Space γ
b : β
f : α → γ
di : IsDenseInducing i
hf : ∀ᶠ (x : β) in 𝓝 b, ∃ c, Tendsto f (comap i (𝓝 x)) (𝓝 c)
φ : β → γ := di.extend f
this : ∀ (b : β), (comap i (𝓝 b)).NeBot
V' : Set γ
V'_in : V' ∈ 𝓝 (φ b)
V'_closed : IsClosed[inst✝¹] V'
V₁ : Set β := {x | Tendsto f (comap i (𝓝 x)) (𝓝 (φ x))}
V₁_in : V₁ ∈ 𝓝 b
⊢ φ ⁻¹' V' ∈ 𝓝 b
Module: Mathlib.Topology.Baire.Lemmas

Goal state before:
pp: X : Type u_1
inst✝² : TopologicalSpace X
inst✝¹ : BaireSpace X
Y : Type u_4
inst✝ : TopologicalSpace Y
p : Y → X
hp : IsOpenEmbedding p
f : ℕ → Set Y
hof : ∀ (n : ℕ), IsOpen[inst✝] (f n)
hdf : ∀ (n : ℕ), Dense (f n)
s : Set X := range p
c : ℕ → Set X := fun n ↦ p '' f n ∪ (closure[inst✝²] s)ᶜ
c_open : ∀ (n : ℕ), IsOpen[inst✝²] (c n)
n : ℕ
⊢ interior (closure[inst✝²] s) ∪ (interior (closure[inst✝²] s))ᶜ ⊆ closure[inst✝²] s ∪ (interior (closure[inst✝²] s))ᶜ

Tactic:
by gcongr; exact interior_subset

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

Goal state before:
pp: X : Type u_1
inst✝² : TopologicalSpace X
inst✝¹ : T2Space X
inst✝ : CompactSpace X
x : X
hs : IsClosed[inst✝²] (⋂ s, ↑s)
a b : Set X
ha : IsClosed[inst✝²] a
hb : IsClosed[inst✝²] b
hab : ⋂ s, ↑s ⊆ a ∪ b
ab_disj : Disjoint a b
u v : Set X
hu : IsOpen[inst✝²] u
hv : IsOpen[inst✝²] v
hau : a ⊆ u
hbv : b ⊆ v
huv : Disjoint u v
s : Set X
H : IsClopen s ∧ x ∈ s ∧ s ⊆ v ∪ u
H1 : IsClopen (s ∩ u)
H2 : IsClopen (s ∩ v)
⊢ ⋂ s, ↑s ⊆ a ∨ ⋂ s, ↑s ⊆ b

Tactic:
by_cases hxu : x ∈ u <;> [left; right]

Goal state after:
case pos
X : Type u_1
inst✝² : TopologicalSpace X
inst✝¹ : T2Space X
inst✝ : CompactSpace X
x : X
hs : IsClosed[inst✝²] (⋂ s, ↑s)
a b : Set X
ha : IsClosed[inst✝²] a
hb : IsClosed[inst✝²] b
hab : ⋂ s, ↑s ⊆ a ∪ b
ab_disj : Disjoint a b
u v : Set X
hu : IsOpen[inst✝²] u
hv : IsOpen[inst✝²] v
hau : a ⊆ u
hbv : b ⊆ v
huv : Disjoint u v
s : Set X
H : IsClopen s ∧ x ∈ s ∧ s ⊆ v ∪ u
H1 : IsClopen (s ∩ u)
H2 : IsClopen (s ∩ v)
hxu : x ∈ u
⊢ ⋂ s, ↑s ⊆ a

case neg
X : Type u_1
inst✝² : TopologicalSpace X
inst✝¹ : T2Space X
inst✝ : CompactSpace X
x : X
hs : IsClosed[inst✝²] (⋂ s, ↑s)
a b : Set X
ha : IsClosed[inst✝²] a
hb : IsClosed[inst✝²] b
hab : ⋂ s, ↑s ⊆ a ∪ b
ab_disj : Disjoint a b
u v : Set X
hu : IsOpen[inst✝²] u
hv : IsOpen[inst✝²] v
hau : a ⊆ u
hbv : b ⊆ v
huv : Disjoint u v
s : Set X
H : IsClopen s ∧ x ∈ s ∧ s ⊆ v ∪ u
H1 : IsClopen (s ∩ u)
H2 : IsClopen (s ∩ v)
hxu : x ∉ u
⊢ ⋂ s, ↑s ⊆ b
Module: Mathlib.Topology.Connected.Clopen

Goal state before:
pp: α : Type u
β : Type v
ι : Type u_1
X : ι → Type u_2
inst✝¹ : TopologicalSpace α
s t u v : Set α
inst✝ : PreconnectedSpace α
x y : α
⊢ mk x = mk y

Tactic:
coe_eq_coe,

Goal state after:
α : Type u
β : Type v
ι : Type u_1
X : ι → Type u_2
inst✝¹ : TopologicalSpace α
s t u v : Set α
inst✝ : PreconnectedSpace α
x y : α
⊢ connectedComponent x = connectedComponent y
Module: Mathlib.Topology.Homeomorph.Lemmas

Goal state before:
pp: X : Type u_1
Y✝ : Type u_2
W : Type u_3
Z : Type u_4
inst✝⁶ : TopologicalSpace X
inst✝⁵ : TopologicalSpace Y✝
inst✝⁴ : TopologicalSpace W
inst✝³ : TopologicalSpace Z
X' : Type u_5
Y' : Type u_6
inst✝² : TopologicalSpace X'
inst✝¹ : TopologicalSpace Y'
ι : Type u_7
ι' : Type u_8
Y : ι' → Type u_9
inst✝ : (j : ι') → TopologicalSpace (Y j)
e : ι ≃ ι'
i : ι
⊢ Continuous[Pi.topologicalSpace, inst✝ (e i)] fun a ↦ (Equiv.piCongrLeft Y e).toFun a (e i)

Tactic:
by
    simpa only [Equiv.toFun_as_coe, Equiv.piCongrLeft_apply_apply] using continuous_apply i

Goal state after:
Module: Mathlib.Topology.UniformSpace.UniformConvergence

Goal state before:
pp: α : Type u_1
β : Type u_2
ι : Type u_4
inst✝ : UniformSpace β
F : ι → α → β
f : α → β
x : α
p : Filter ι
⊢ (∀ s ∈ 𝓤 β, (fun q ↦ (f q.2, F q.1 q.2)) ⁻¹' s ∈ p ×ˢ 𝓟 {x}) ↔ ∀ s ∈ 𝓤 β, (fun x_1 ↦ (f x, F x_1 x)) ⁻¹' s ∈ p

Tactic:
exact forall₂_congr fun u _ => by simp [preimage]

Goal state after:
Module: Mathlib.Topology.UniformSpace.CompleteSeparated

Goal state before:
pp: α : Type u_1
inst✝¹ : UniformSpace α
inst✝ : T0Space α
s : Set α
h : IsComplete s
a : α
ha : ClusterPt a (𝓟 s)
f : Filter α := 𝓝[s] a
⊢ a ∈ s

Tactic:
have : Cauchy f := cauchy_nhds.mono' ha inf_le_left

Goal state after:
α : Type u_1
inst✝¹ : UniformSpace α
inst✝ : T0Space α
s : Set α
h : IsComplete s
a : α
ha : ClusterPt a (𝓟 s)
f : Filter α := 𝓝[s] a
this : Cauchy f
⊢ a ∈ s
Module: Mathlib.Topology.UniformSpace.Equicontinuity

Goal state before:
pp: ι : Type u_1
κ : Type u_2
X : Type u_3
α' : Type u_7
tX : TopologicalSpace X
u : κ → UniformSpace α'
F : ι → X → α'
⊢ Continuous[tX, inferInstance] (⇑ofFun ∘ swap F) ↔ ∀ (k : κ), Continuous[tX, inferInstance] (⇑ofFun ∘ swap F)

Tactic:
rw [UniformFun.iInf_eq, toTopologicalSpace_iInf, continuous_iInf_rng]

Goal state after:
Module: Mathlib.Topology.UniformSpace.Equicontinuity

Goal state before:
pp: ι : Type u_1
κ : Type u_2
α : Type u_6
β : Type u_8
uα : UniformSpace α
uβ : UniformSpace β
p : κ → Prop
s : κ → Set (β × β)
F : ι → β → α
hβ : (𝓤 β).HasBasis p s
⊢ Tendsto (fun x ↦ ((⇑ofFun ∘ swap F) x.1, (⇑ofFun ∘ swap F) x.2)) (𝓤 β) (𝓤 (ι →ᵤ α)) ↔
    ∀ U ∈ 𝓤 α, ∃ k, p k ∧ ∀ (x y : β), (x, y) ∈ s k → ∀ (i : ι), (F i x, F i y) ∈ U

Tactic:
hβ.tendsto_iff (UniformFun.hasBasis_uniformity ι α)

Goal state after:
ι : Type u_1
κ : Type u_2
α : Type u_6
β : Type u_8
uα : UniformSpace α
uβ : UniformSpace β
p : κ → Prop
s : κ → Set (β × β)
F : ι → β → α
hβ : (𝓤 β).HasBasis p s
⊢ (∀ ib ∈ 𝓤 α, ∃ ia, p ia ∧ ∀ x ∈ s ia, ((⇑ofFun ∘ swap F) x.1, (⇑ofFun ∘ swap F) x.2) ∈ UniformFun.gen ι α ib) ↔
    ∀ U ∈ 𝓤 α, ∃ k, p k ∧ ∀ (x y : β), (x, y) ∈ s k → ∀ (i : ι), (F i x, F i y) ∈ U
Module: Mathlib.Topology.UniformSpace.Equicontinuity

Goal state before:
pp: ι : Type u_1
κ : Type u_2
α : Type u_6
β : Type u_8
uα : UniformSpace α
uβ : UniformSpace β
p : κ → Prop
s : κ → Set (β × β)
F : ι → β → α
S : Set β
hβ : (𝓤 β ⊓ 𝓟 (S ×ˢ S)).HasBasis p s
⊢ Tendsto (fun x ↦ ((⇑ofFun ∘ swap F) x.1, (⇑ofFun ∘ swap F) x.2)) (𝓤 β ⊓ 𝓟 (S ×ˢ S)) (𝓤 (ι →ᵤ α)) ↔
    ∀ U ∈ 𝓤 α, ∃ k, p k ∧ ∀ (x y : β), (x, y) ∈ s k → ∀ (i : ι), (F i x, F i y) ∈ U

Tactic:
hβ.tendsto_iff (UniformFun.hasBasis_uniformity ι α)

Goal state after:
ι : Type u_1
κ : Type u_2
α : Type u_6
β : Type u_8
uα : UniformSpace α
uβ : UniformSpace β
p : κ → Prop
s : κ → Set (β × β)
F : ι → β → α
S : Set β
hβ : (𝓤 β ⊓ 𝓟 (S ×ˢ S)).HasBasis p s
⊢ (∀ ib ∈ 𝓤 α, ∃ ia, p ia ∧ ∀ x ∈ s ia, ((⇑ofFun ∘ swap F) x.1, (⇑ofFun ∘ swap F) x.2) ∈ UniformFun.gen ι α ib) ↔
    ∀ U ∈ 𝓤 α, ∃ k, p k ∧ ∀ (x y : β), (x, y) ∈ s k → ∀ (i : ι), (F i x, F i y) ∈ U
Module: Mathlib.Topology.UniformSpace.Equicontinuity

Goal state before:
pp: ι : Type u_1
α : Type u_6
β : Type u_8
uα : UniformSpace α
uβ : UniformSpace β
κ₁ : Type u_11
κ₂ : Type u_12
p₁ : κ₁ → Prop
s₁ : κ₁ → Set (β × β)
p₂ : κ₂ → Prop
s₂ : κ₂ → Set (α × α)
F : ι → β → α
hβ : (𝓤 β).HasBasis p₁ s₁
hα : (𝓤 α).HasBasis p₂ s₂
⊢ UniformEquicontinuous F ↔
    ∀ (k₂ : κ₂), p₂ k₂ → ∃ k₁, p₁ k₁ ∧ ∀ (x y : β), (x, y) ∈ s₁ k₁ → ∀ (i : ι), (F i x, F i y) ∈ s₂ k₂

Tactic:
by
  rw [uniformEquicontinuous_iff_uniformContinuous, UniformContinuous,
    hβ.tendsto_iff (UniformFun.hasBasis_uniformity_of_basis ι α hα)]
  simp only [Prod.forall]
  rfl

Goal state after:
Module: Mathlib.Topology.UniformSpace.UniformConvergenceTopology

Goal state before:
pp: α : Type u_1
β : Type u_2
γ : Type u_3
ι : Type u_4
s : Set α
p : Filter ι
inst✝¹ : UniformSpace β
𝔖 : Set (Set α)
inst✝ : CompleteSpace β
⊢ CompleteSpace (α →ᵤ[𝔖] β)

Tactic:
rcases isEmpty_or_nonempty β
  · infer_instance
  · refine ⟨fun {F} hF ↦ ?_⟩
    have := hF.1
    have : ∀ x ∈ ⋃₀ 𝔖, ∃ y : β, Tendsto (toFun 𝔖 · x) F (𝓝 y) := fun x hx ↦
      CompleteSpace.complete (hF.map (uniformContinuous_eval_of_mem_sUnion _ _ hx))
    choose! g hg using this
    use ofFun 𝔖 g
    simp_rw [UniformOnFun.nhds_eq_of_basis _ _ uniformity_hasBasis_closed, le_iInf₂_iff,
      le_principal_iff]
    intro s hs U ⟨hU, hUc⟩
    rcases cauchy_iff.mp hF |>.2 _ <| UniformOnFun.gen_mem_uniformity _ _ hs hU
      with ⟨V, hV, hVU⟩
    filter_upwards [hV] with f hf x hx
    refine hUc.mem_of_tendsto ((hg x ⟨s, hs, hx⟩).prodMk_nhds tendsto_const_nhds) ?_
    filter_upwards [hV] with g' hg' using hVU (mk_mem_prod hg' hf) _ hx

Goal state after:
Module: Mathlib.Topology.Algebra.ConstMulAction

Goal state before:
pp: G : Type u_4
inst✝² : Group G
inst✝¹ : TopologicalSpace G
inst✝ : ContinuousConstSMul G G
g : G
s : Set G
⊢ g • s ∈ 𝓝 g ↔ s ∈ 𝓝 1

Tactic:
← smul_mem_nhds_smul_iff g⁻¹

Goal state after:
G : Type u_4
inst✝² : Group G
inst✝¹ : TopologicalSpace G
inst✝ : ContinuousConstSMul G G
g : G
s : Set G
⊢ g⁻¹ • g • s ∈ 𝓝 (g⁻¹ • g) ↔ s ∈ 𝓝 1
Module: Mathlib.Topology.Algebra.Monoid

Goal state before:
pp: M : Type u_3
inst✝² : TopologicalSpace M
inst✝¹ : Mul M
inst✝ : ContinuousMul M
a b : M
⊢ map (Function.uncurry fun x1 x2 ↦ x1 * x2) (𝓝 (a, b)) ≤ 𝓝 (a * b)

Tactic:
exact continuous_mul.tendsto _

Goal state after:
Module: Mathlib.Topology.Algebra.ConstMulAction

Goal state before:
pp: case neg
M : Type u_1
α : Type u_2
β : Type u_3
Γ : Type u_4
inst✝⁶ : Group Γ
T : Type u_5
inst✝⁵ : TopologicalSpace T
inst✝⁴ : MulAction Γ T
inst✝³ : T2Space T
inst✝² : LocallyCompactSpace T
inst✝¹ : ContinuousConstSMul Γ T
inst✝ : ProperlyDiscontinuousSMul Γ T
this : Setoid T := MulAction.orbitRel Γ T
Q : Type u_5 := Quotient (MulAction.orbitRel Γ T)
f : T → Q := Quotient.mk'
f_op : IsOpenMap f
i✝ : Quotient (MulAction.orbitRel Γ T)
x₀ : T
j✝ : Quotient (MulAction.orbitRel Γ T)
y₀ : T
hxy : f x₀ ≠ f y₀
hγx₀y₀ : ∀ (γ : Γ), γ • x₀ ≠ y₀
K₀ : Set T
hK₀ : IsCompact K₀
K₀_in : K₀ ∈ 𝓝 x₀
L₀ : Set T
hL₀ : IsCompact L₀
L₀_in : L₀ ∈ 𝓝 y₀
bad_Γ_set : Set Γ := {γ | ((fun x ↦ γ • x) '' K₀ ∩ L₀).Nonempty}
bad_Γ_finite : bad_Γ_set.Finite
u v : Γ → Set T
hu : ∀ (γ : Γ), u γ ∈ 𝓝 (γ • x₀)
hv : ∀ (γ : Γ), v γ ∈ 𝓝 y₀
u_v_disjoint : ∀ (γ : Γ), Disjoint (u γ) (v γ)
U₀₀ : Set T := ⋂ γ ∈ bad_Γ_set, (fun x ↦ γ • x) ⁻¹' u γ
U₀ : Set T := U₀₀ ∩ K₀
V₀₀ : Set T := ⋂ γ ∈ bad_Γ_set, v γ
V₀ : Set T := V₀₀ ∩ L₀
U_nhds : f '' U₀ ∈ 𝓝 (f x₀)
V_nhds : f '' V₀ ∈ 𝓝 (f y₀)
x : T
x_in_U₀₀ : x ∈ U₀₀
x_in_K₀ : x ∈ K₀
γ : Γ
H : γ ∉ bad_Γ_set
⊢ γ • x ∉ V₀

Tactic:
· rintro ⟨-, h'⟩
    simp only [bad_Γ_set, image_smul, not_nonempty_iff_eq_empty, mem_ofPred_eq] at H
    exact eq_empty_iff_forall_notMem.mp H (γ • x) ⟨mem_image_of_mem _ x_in_K₀, h'⟩

Goal state after:
Module: Mathlib.Topology.Maps.Proper.Basic

Goal state before:
pp: case mpr
X : Type u_1
Y : Type u_2
inst✝¹ : TopologicalSpace X
inst✝ : TopologicalSpace Y
f : X → Y
x✝ : Continuous[inst✝¹, inst✝] f
H : ∀ ⦃𝒰 : Ultrafilter X⦄ ⦃y : Y⦄, Tendsto f (↑𝒰) (𝓝 y) → ∃ x, f x = y ∧ ↑𝒰 ≤ 𝓝 x
⊢ ∀ ⦃ℱ : Filter X⦄ ⦃y : Y⦄, MapClusterPt y ℱ f → ∃ x, f x = y ∧ ClusterPt x ℱ

Tactic:
simp_rw [MapClusterPt, ClusterPt, ← Filter.push_pull', map_neBot_iff, ← exists_ultrafilter_iff,
      forall_exists_index]

Goal state after:
case mpr
X : Type u_1
Y : Type u_2
inst✝¹ : TopologicalSpace X
inst✝ : TopologicalSpace Y
f : X → Y
x✝ : Continuous[inst✝¹, inst✝] f
H : ∀ ⦃𝒰 : Ultrafilter X⦄ ⦃y : Y⦄, Tendsto f (↑𝒰) (𝓝 y) → ∃ x, f x = y ∧ ↑𝒰 ≤ 𝓝 x
⊢ ∀ ⦃ℱ : Filter X⦄ ⦃y : Y⦄ (x : Ultrafilter X), ↑x ≤ comap f (𝓝 y) ⊓ ℱ → ∃ x, f x = y ∧ ∃ u, ↑u ≤ 𝓝 x ⊓ ℱ
Module: Mathlib.Topology.Maps.Proper.Basic

Goal state before:
pp: case right
ι : Type u_5
X : ι → Type u_6
Y : ι → Type u_7
inst✝¹ : (i : ι) → TopologicalSpace (X i)
inst✝ : (i : ι) → TopologicalSpace (Y i)
f : (i : ι) → X i → Y i
h :
  ∀ (i : ι),
    Continuous[inst✝¹ i, inst✝ i] (f i) ∧
      ∀ ⦃𝒰 : Ultrafilter (X i)⦄ ⦃y : Y i⦄, Tendsto (f i) (↑𝒰) (𝓝 y) → ∃ x, f i x = y ∧ ↑𝒰 ≤ 𝓝 x
⊢ ∀ ⦃𝒰 : Ultrafilter ((i : ι) → X i)⦄ ⦃y : (i : ι) → Y i⦄,
    Tendsto (fun x i ↦ f i (x i)) (↑𝒰) (𝓝 y) → ∃ x, (fun i ↦ f i (x i)) = y ∧ ↑𝒰 ≤ 𝓝 x

Tactic:
· intro 𝒰 y hy
  -- That means that each `f i` tends to `y i` along `map (eval i) 𝒰`.
    have : ∀ i, Tendsto (f i) (Ultrafilter.map (eval i) 𝒰) (𝓝 (y i)) := by
      simpa [tendsto_pi_nhds] using! hy
  -- Thus, by properness of all the `f i`s, we can choose some `x : Π i, X i` such that, for all
  -- `i`, `f i (x i) = y i` and `map (eval i) 𝒰` tends to  `x i`.
    choose x hxy hx using fun i ↦ (h i).2 (this i)
  -- By the properties of the product topology, that means that `𝒰` tends to `x`,
  -- which completes the proof since `(Π i, f i) x = y`.
    refine ⟨x, funext hxy, ?_⟩
    rwa [nhds_pi, le_pi]

Goal state after: