mathlib-initiative/mathlib-tactics huggingface dataset:
Module: Mathlib.MeasureTheory.Function.StronglyMeasurable.AEStronglyMeasurable

Goal state before:
pp: case mpr
α : Type u_1
β : Type u_2
inst✝¹ : TopologicalSpace β
m₀ : MeasurableSpace α
μ : Measure α
f : α → β
inst✝ : Zero β
s : Set α
hs : MeasurableSet s
⊢ AEStronglyMeasurable f (μ.restrict s) → AEStronglyMeasurable (s.indicator f) μ

Tactic:
intro h

Goal state after:
case mpr
α : Type u_1
β : Type u_2
inst✝¹ : TopologicalSpace β
m₀ : MeasurableSpace α
μ : Measure α
f : α → β
inst✝ : Zero β
s : Set α
hs : MeasurableSet s
h : AEStronglyMeasurable f (μ.restrict s)
⊢ AEStronglyMeasurable (s.indicator f) μ
Module: Mathlib.MeasureTheory.Integral.Lebesgue.Add

Goal state before:
pp: α : Type u_1
m : MeasurableSpace α
μ : Measure α
f : ℕ → α → ℝ≥0∞
hf : ∀ (n : ℕ), AEMeasurable (f n) μ
h_mono : ∀ᵐ (x : α) ∂μ, Monotone fun n ↦ f n x
p : α → (ℕ → ℝ≥0∞) → Prop := fun x f' ↦ Monotone f'
hp : ∀ᵐ (x : α) ∂μ, p x fun i ↦ f i x
h_ae_seq_mono : Monotone (aeSeq hf p)
⊢ ∫⁻ (a : α), (⨆ n, aeSeq hf p n) a ∂μ = ⨆ n, ∫⁻ (a : α), f n a ∂μ

Tactic:
iSup_apply

Goal state after:
α : Type u_1
m : MeasurableSpace α
μ : Measure α
f : ℕ → α → ℝ≥0∞
hf : ∀ (n : ℕ), AEMeasurable (f n) μ
h_mono : ∀ᵐ (x : α) ∂μ, Monotone fun n ↦ f n x
p : α → (ℕ → ℝ≥0∞) → Prop := fun x f' ↦ Monotone f'
hp : ∀ᵐ (x : α) ∂μ, p x fun i ↦ f i x
h_ae_seq_mono : Monotone (aeSeq hf p)
⊢ ∫⁻ (a : α), ⨆ i, aeSeq hf p i a ∂μ = ⨆ n, ∫⁻ (a : α), f n a ∂μ
Module: Mathlib.MeasureTheory.Integral.Lebesgue.Basic

Goal state before:
pp: α : Type u_1
m : MeasurableSpace α
μ : Measure α
f : α → ℝ≥0∞
h : ∫⁻ (x : α), f x ∂μ ≠ ∞
ε : ℝ≥0∞
hε : ε ≠ 0
ε₂ : ℝ≥0∞
hε₂0 : 0 < ε₂
hε₂ε : ε₂ < ε
ε₁ : ℝ≥0∞
hε₁0 : 0 < ε₁
hε₁₂ : ε₁ < ε₂
φ : α →ₛ ℝ≥0
left✝ : ∀ (x : α), ↑(φ x) ≤ f x
hφ : ∀ (ψ : α →ₛ ℝ≥0), (∀ (x : α), ↑(ψ x) ≤ f x) → (SimpleFunc.map ofNNReal (ψ - φ)).lintegral μ < ε₁
C : ℝ≥0
hC : ∀ (x : α), φ x ≤ C
s : Set α
hs : μ s < (ε₂ - ε₁) / ↑C
ψ : α →ₛ ℝ≥0
hψ : ∀ (x : α), ↑(ψ x) ≤ f x
⊢ ↑C * ((ε₂ - ε₁) / ↑C) + ε₁ ≤ ε₂ - ε₁ + ε₁

Tactic:
by gcongr; apply mul_div_le

Goal state after:
Module: Mathlib.MeasureTheory.Integral.Lebesgue.Basic

Goal state before:
pp: α : Type u_1
m : MeasurableSpace α
μ : Measure α
f : α → ℝ≥0∞
s : Set α
g : α →ₛ ℝ≥0∞
hg : ⇑g ≤ fun a ↦ s.indicator f a
⊢ g.lintegral μ ≤ ⨆ g, ⨆ (_ : ⇑g ≤ fun a ↦ f a), g.lintegral (μ.restrict s)

Tactic:
have : g ≤ f := hg.trans (indicator_le_self s f)

Goal state after:
α : Type u_1
m : MeasurableSpace α
μ : Measure α
f : α → ℝ≥0∞
s : Set α
g : α →ₛ ℝ≥0∞
hg : ⇑g ≤ fun a ↦ s.indicator f a
this : ⇑g ≤ f
⊢ g.lintegral μ ≤ ⨆ g, ⨆ (_ : ⇑g ≤ fun a ↦ f a), g.lintegral (μ.restrict s)
Module: Mathlib.MeasureTheory.Integral.Lebesgue.Basic

Goal state before:
pp: α : Type u_1
m : MeasurableSpace α
μ ν : Measure α
⊢ (∀ (f : α → ℝ≥0∞), Measurable f → ∫⁻ (a : α), f a ∂μ = ∫⁻ (a : α), f a ∂ν) → μ = ν

Tactic:
intro h

Goal state after:
α : Type u_1
m : MeasurableSpace α
μ ν : Measure α
h : ∀ (f : α → ℝ≥0∞), Measurable f → ∫⁻ (a : α), f a ∂μ = ∫⁻ (a : α), f a ∂ν
⊢ μ = ν
Module: Mathlib.Topology.Perfect

Goal state before:
pp: case mp
α : Type u_1
inst✝¹ : TopologicalSpace α
C : Set α
inst✝ : T1Space α
⊢ Preperfect C → Perfect (closure[inst✝¹] C)

Tactic:
intro h

Goal state after:
case mp
α : Type u_1
inst✝¹ : TopologicalSpace α
C : Set α
inst✝ : T1Space α
h : Preperfect C
⊢ Perfect (closure[inst✝¹] C)
Module: Mathlib.Topology.Perfect

Goal state before:
pp: case mpr
α : Type u_1
inst✝¹ : TopologicalSpace α
C : Set α
inst✝ : T1Space α
⊢ Perfect (closure[inst✝¹] C) → Preperfect C

Tactic:
intro h

Goal state after:
case mpr
α : Type u_1
inst✝¹ : TopologicalSpace α
C : Set α
inst✝ : T1Space α
h : Perfect (closure[inst✝¹] C)
⊢ Preperfect C
Module: Mathlib.Topology.Perfect

Goal state before:
pp: α : Type u_1
inst✝¹ : TopologicalSpace α
C : Set α
inst✝ : SecondCountableTopology α
hclosed : IsClosed[inst✝¹] C
b : Set (Set α)
bct : b.Countable
left✝ : ∅ ∉ b
bbasis : IsTopologicalBasis b
v : Set (Set α) := {U | U ∈ b ∧ (U ∩ C).Countable}
V : Set α := ⋃ U ∈ v, U
D : Set α := C \ V
Vct : (V ∩ C).Countable
x : α
xD : x ∈ D
E : Set α
xE : E ∈ 𝓝 x
⊢ ¬(E ∩ D).Countable

Tactic:
intro h

Goal state after:
α : Type u_1
inst✝¹ : TopologicalSpace α
C : Set α
inst✝ : SecondCountableTopology α
hclosed : IsClosed[inst✝¹] C
b : Set (Set α)
bct : b.Countable
left✝ : ∅ ∉ b
bbasis : IsTopologicalBasis b
v : Set (Set α) := {U | U ∈ b ∧ (U ∩ C).Countable}
V : Set α := ⋃ U ∈ v, U
D : Set α := C \ V
Vct : (V ∩ C).Countable
x : α
xD : x ∈ D
E : Set α
xE : E ∈ 𝓝 x
h : (E ∩ D).Countable
⊢ False
Module: Mathlib.Analysis.Normed.Group.FunctionSeries

Goal state before:
pp: α : Type u_1
β : Type u_2
F : Type u_3
inst✝² : NormedAddCommGroup F
inst✝¹ : CompleteSpace F
u : α → ℝ
inst✝ : TopologicalSpace β
f : α → β → F
hf : ∀ (i : α), Continuous[inst✝, PseudoMetricSpace.toUniformSpace.toTopologicalSpace] (f i)
hu : Summable u
hfu : ∀ (n : α) (x : β), ‖f n x‖ ≤ u n
⊢ Continuous[inst✝, PseudoMetricSpace.toUniformSpace.toTopologicalSpace] fun x ↦ ∑' (n : α), f n x

Tactic:
← continuousOn_univ

Goal state after:
α : Type u_1
β : Type u_2
F : Type u_3
inst✝² : NormedAddCommGroup F
inst✝¹ : CompleteSpace F
u : α → ℝ
inst✝ : TopologicalSpace β
f : α → β → F
hu : Summable u
hfu : ∀ (n : α) (x : β), ‖f n x‖ ≤ u n
hf : ∀ (i : α), ContinuousOn (f i) univ
⊢ ContinuousOn (fun x ↦ ∑' (n : α), f n x) univ
Module: Mathlib.Topology.UnitInterval

Goal state before:
pp: a b : ℝ
x y z : ↑(Icc a b)
s t : ↑unitInterval
hs : ¬↑s = 1
ht : ¬↑t = 1
⊢ 1 - ↑s * ↑t ≠ 0

Tactic:
intro h

Goal state after:
a b : ℝ
x y z : ↑(Icc a b)
s t : ↑unitInterval
hs : ¬↑s = 1
ht : ¬↑t = 1
h : 1 - ↑s * ↑t = 0
⊢ False
Module: Mathlib.Topology.MetricSpace.Gluing

Goal state before:
pp: X : Type u
Y : Type v
inst✝¹ : MetricSpace X
inst✝ : MetricSpace Y
x y : X ⊕ Y
⊢ Sum.dist x y = Sum.dist y x

Tactic:
cases x

Goal state after:
case inl
X : Type u
Y : Type v
inst✝¹ : MetricSpace X
inst✝ : MetricSpace Y
y : X ⊕ Y
val✝ : X
⊢ Sum.dist (Sum.inl val✝) y = Sum.dist y (Sum.inl val✝)

case inr
X : Type u
Y : Type v
inst✝¹ : MetricSpace X
inst✝ : MetricSpace Y
y : X ⊕ Y
val✝ : Y
⊢ Sum.dist (Sum.inr val✝) y = Sum.dist y (Sum.inr val✝)
Module: Mathlib.Topology.MetricSpace.PiNat

Goal state before:
pp: case mpr
E : ℕ → Type u_1
x y : (n : ℕ) → E n
n : ℕ
⊢ cylinder y n = cylinder x n → y ∈ cylinder x n

Tactic:
intro h

Goal state after:
case mpr
E : ℕ → Type u_1
x y : (n : ℕ) → E n
n : ℕ
h : cylinder y n = cylinder x n
⊢ y ∈ cylinder x n
Module: Mathlib.Topology.MetricSpace.PiNat

Goal state before:
pp: E : ℕ → Type u_1
x y : (n : ℕ) → E n
n : ℕ
⊢ y ∈ cylinder x n ↔ x ∈ cylinder y n

Tactic:
by
  simp [eq_comm]

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

Goal state before:
pp: case mp
E : ℕ → Type u_1
x y : (n : ℕ) → E n
hne : x ≠ y
i : ℕ
⊢ x ∈ cylinder y i → i ≤ firstDiff x y

Tactic:
intro h

Goal state after:
case mp
E : ℕ → Type u_1
x y : (n : ℕ) → E n
hne : x ≠ y
i : ℕ
h : x ∈ cylinder y i
⊢ i ≤ firstDiff x y
Module: Mathlib.Topology.MetricSpace.PiNat

Goal state before:
pp: case mp
α : Type u_2
x y : ℕ → α
n : ℕ
⊢ res x n = res y n → ∀ ⦃m : ℕ⦄, m < n → x m = y m

Tactic:
intro h

Goal state after:
case mp
α : Type u_2
x y : ℕ → α
n : ℕ
h : res x n = res y n
⊢ ∀ ⦃m : ℕ⦄, m < n → x m = y m
Module: Mathlib.Topology.MetricSpace.PiNat

Goal state before:
pp: case mpr
α : Type u_2
x y : ℕ → α
n : ℕ
⊢ (∀ ⦃m : ℕ⦄, m < n → x m = y m) → res x n = res y n

Tactic:
intro h

Goal state after:
case mpr
α : Type u_2
x y : ℕ → α
n : ℕ
h : ∀ ⦃m : ℕ⦄, m < n → x m = y m
⊢ res x n = res y n
Module: Mathlib.Topology.MetricSpace.Gluing

Goal state before:
pp: X : Type u
Y : Type v
Z : Type w
inst✝¹ : MetricSpace X
inst✝ : MetricSpace Y
x : X ⊕ Y
⊢ Sum.dist x x = 0

Tactic:
cases x

Goal state after:
case inl
X : Type u
Y : Type v
Z : Type w
inst✝¹ : MetricSpace X
inst✝ : MetricSpace Y
val✝ : X
⊢ Sum.dist (Sum.inl val✝) (Sum.inl val✝) = 0

case inr
X : Type u
Y : Type v
Z : Type w
inst✝¹ : MetricSpace X
inst✝ : MetricSpace Y
val✝ : Y
⊢ Sum.dist (Sum.inr val✝) (Sum.inr val✝) = 0
Module: Mathlib.Topology.MetricSpace.PiNat

Goal state before:
pp: case inr.mpr
E : ℕ → Type u_1
x y : (n : ℕ) → E n
n : ℕ
hne : y ≠ x
⊢ n ≤ firstDiff y x → ∀ i < n, y i = x i

Tactic:
intro h

Goal state after:
case inr.mpr
E : ℕ → Type u_1
x y : (n : ℕ) → E n
n : ℕ
hne : y ≠ x
h : n ≤ firstDiff y x
⊢ ∀ i < n, y i = x i
Module: Mathlib.Topology.MetricSpace.Gluing

Goal state before:
pp: ι : Type u_1
E : ι → Type u_2
inst✝ : (i : ι) → MetricSpace (E i)
x y : (i : ι) × E i
h : dist x y < 1
⊢ x.fst = y.fst

Tactic:
cases x

Goal state after:
case mk
ι : Type u_1
E : ι → Type u_2
inst✝ : (i : ι) → MetricSpace (E i)
y : (i : ι) × E i
fst✝ : ι
snd✝ : E fst✝
h : dist ⟨fst✝, snd✝⟩ y < 1
⊢ ⟨fst✝, snd✝⟩.fst = y.fst
Module: Mathlib.Topology.MetricSpace.Gluing

Goal state before:
pp: case inr.inr.inr
ι : Type u_1
E : ι → Type u_2
inst✝ : (i : ι) → MetricSpace (E i)
i : ι
x : E i
j : ι
y : E j
k : ι
z : E k
hik : i ≠ k
hij : i ≠ j
hjk : j ≠ k
⊢ dist ⟨i, x⟩ ⟨k, z⟩ ≤ dist ⟨i, x⟩ ⟨j, y⟩ + dist ⟨j, y⟩ ⟨k, z⟩

Tactic:
· simp only [hik, hij, hjk, Sigma.dist_ne, Ne, not_false_iff]
        calc
          dist x (Nonempty.some ⟨x⟩) + 1 + dist (Nonempty.some ⟨z⟩) z =
              dist x (Nonempty.some ⟨x⟩) + 1 + 0 + (0 + 0 + dist (Nonempty.some ⟨z⟩) z) := by
            simp only [add_zero, zero_add]
          _ ≤ _ := by apply_rules [add_le_add, zero_le_one, dist_nonneg, le_rfl]

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

Goal state before:
pp: case refine_3.inr
ι : Type u_1
E : ι → Type u_2
inst✝ : (i : ι) → MetricSpace (E i)
i : ι
x : E i
j : ι
y : E j
hij : i ≠ j
⊢ Sigma.dist ⟨i, x⟩ ⟨j, y⟩ = 0 → ⟨i, x⟩ = ⟨j, y⟩

Tactic:
intro h

Goal state after:
case refine_3.inr
ι : Type u_1
E : ι → Type u_2
inst✝ : (i : ι) → MetricSpace (E i)
i : ι
x : E i
j : ι
y : E j
hij : i ≠ j
h : Sigma.dist ⟨i, x⟩ ⟨j, y⟩ = 0
⊢ ⟨i, x⟩ = ⟨j, y⟩
Module: Mathlib.Topology.MetricSpace.PiNat

Goal state before:
pp: case mpr
E : ℕ → Type u_1
inst✝¹ : (n : ℕ) → TopologicalSpace (E n)
inst✝ : ∀ (n : ℕ), DiscreteTopology (E n)
s : Set ((n : ℕ) → E n)
⊢ (∀ x ∈ s, ∃ ε > 0, ∀ (y : (n : ℕ) → E n), dist x y < ε → y ∈ s) → IsOpen[Pi.topologicalSpace] s

Tactic:
intro h

Goal state after:
case mpr
E : ℕ → Type u_1
inst✝¹ : (n : ℕ) → TopologicalSpace (E n)
inst✝ : ∀ (n : ℕ), DiscreteTopology (E n)
s : Set ((n : ℕ) → E n)
h : ∀ x ∈ s, ∃ ε > 0, ∀ (y : (n : ℕ) → E n), dist x y < ε → y ∈ s
⊢ IsOpen[Pi.topologicalSpace] s
Module: Mathlib.Topology.MetricSpace.PiNat

Goal state before:
pp: case pos
E : ℕ → Type u_1
inst✝¹ : (n : ℕ) → TopologicalSpace (E n)
inst✝ : ∀ (n : ℕ), DiscreteTopology (E n)
s : Set ((n : ℕ) → E n)
hs : IsClosed[Pi.topologicalSpace] s
hne : s.Nonempty
x : (n : ℕ) → E n
hx : x ∈ s
⊢ (s ∩ cylinder x (longestPrefix x s)).Nonempty

pp: case neg
E : ℕ → Type u_1
inst✝¹ : (n : ℕ) → TopologicalSpace (E n)
inst✝ : ∀ (n : ℕ), DiscreteTopology (E n)
s : Set ((n : ℕ) → E n)
hs : IsClosed[Pi.topologicalSpace] s
hne : s.Nonempty
x : (n : ℕ) → E n
hx : x ∉ s
⊢ (s ∩ cylinder x (longestPrefix x s)).Nonempty

Tactic:
· exact ⟨x, hx, self_mem_cylinder _ _⟩

Goal state after:
case neg
E : ℕ → Type u_1
inst✝¹ : (n : ℕ) → TopologicalSpace (E n)
inst✝ : ∀ (n : ℕ), DiscreteTopology (E n)
s : Set ((n : ℕ) → E n)
hs : IsClosed[Pi.topologicalSpace] s
hne : s.Nonempty
x : (n : ℕ) → E n
hx : x ∉ s
⊢ (s ∩ cylinder x (longestPrefix x s)).Nonempty
Module: Mathlib.MeasureTheory.Constructions.Polish.Basic

Goal state before:
pp: case mp
α : Type u_1
inst✝ : TopologicalSpace α
s : Set α
⊢ AnalyticSet s → ∃ β h, ∃ (_ : PolishSpace β), ∃ f, Continuous[_, inst✝] f ∧ range f = s

Tactic:
intro h

Goal state after:
case mp
α : Type u_1
inst✝ : TopologicalSpace α
s : Set α
h : AnalyticSet s
⊢ ∃ β h, ∃ (_ : PolishSpace β), ∃ f, Continuous[_, inst✝] f ∧ range f = s
Module: Mathlib.Topology.MetricSpace.PiNat

Goal state before:
pp: E : ℕ → Type u_1
inst✝¹ : (n : ℕ) → TopologicalSpace (E n)
inst✝ : ∀ (n : ℕ), DiscreteTopology (E n)
s : Set ((n : ℕ) → E n)
hs : IsClosed[Pi.topologicalSpace] s
hne : s.Nonempty
f : ((n : ℕ) → E n) → (n : ℕ) → E n := fun x ↦ if x ∈ s then x else ⋯.some
fs : ∀ x ∈ s, f x = x
x y : (n : ℕ) → E n
hxy : x ≠ y
hfxfy : x ≠ f y
I2 : cylinder x (firstDiff x y) = cylinder y (firstDiff x y)
xs : x ∈ s
ys : y ∉ s
A : (s ∩ cylinder y (longestPrefix y s)).Nonempty
fy : f y = A.some
⊢ A.some ∈ cylinder y (firstDiff y x)

Tactic:
apply cylinder_anti y _ A.some_mem.2

Goal state after:
E : ℕ → Type u_1
inst✝¹ : (n : ℕ) → TopologicalSpace (E n)
inst✝ : ∀ (n : ℕ), DiscreteTopology (E n)
s : Set ((n : ℕ) → E n)
hs : IsClosed[Pi.topologicalSpace] s
hne : s.Nonempty
f : ((n : ℕ) → E n) → (n : ℕ) → E n := ⋯
fs : ∀ x ∈ s, f x = x
x y : (n : ℕ) → E n
hxy : x ≠ y
hfxfy : x ≠ f y
I2 : cylinder x (firstDiff x y) = cylinder y (firstDiff x y)
xs : x ∈ s
ys : y ∉ s
A : (s ∩ cylinder y (longestPrefix y s)).Nonempty
fy : f y = A.some
⊢ firstDiff y x ≤ longestPrefix y s
Module: Mathlib.MeasureTheory.Measure.MutuallySingular

Goal state before:
pp: α : Type u_1
m0 : MeasurableSpace α
μ ν : Measure α
h : Disjoint μ ν
n : ℕ
x✝ : Set α
| (1 / 2) ^ n

Tactic:
1

Goal state after:
α : Type u_1
m0 : MeasurableSpace α
μ ν : Measure α
h : Disjoint μ ν
n : ℕ
x✝ : Set α
| 1 / 2
Module: Mathlib.MeasureTheory.Measure.MutuallySingular

Goal state before:
pp: α : Type u_1
m0 : MeasurableSpace α
μ ν : Measure α
h : Disjoint μ ν
n : ℕ
x✝ : Set α
| 1 / 2

Tactic:
equals ((1 : ℝ≥0) / (2 : ℝ≥0)) => rfl

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

Goal state before:
pp: case pos
E : ℕ → Type u_1
inst✝¹ : (n : ℕ) → TopologicalSpace (E n)
inst✝ : ∀ (n : ℕ), DiscreteTopology (E n)
s : Set ((n : ℕ) → E n)
hs : IsClosed[Pi.topologicalSpace] s
hne : s.Nonempty
f : ((n : ℕ) → E n) → (n : ℕ) → E n := fun x ↦ if x ∈ s then x else ⋯.some
fs : ∀ x ∈ s, f x = x
x y : (n : ℕ) → E n
hxy : x ≠ y
hfxfy : f x ≠ f y
I2 : cylinder x (firstDiff x y) = cylinder y (firstDiff x y)
xs : x ∉ s
ys : y ∉ s
Ax : (s ∩ cylinder x (longestPrefix x s)).Nonempty
fx : f x = Ax.some
Ay : (s ∩ cylinder y (longestPrefix y s)).Nonempty
fy : f y = Ay.some
H : longestPrefix x s < firstDiff x y ∨ longestPrefix y s < firstDiff x y
⊢ firstDiff x y ≤ firstDiff (f x) (f y)

pp: case neg
E : ℕ → Type u_1
inst✝¹ : (n : ℕ) → TopologicalSpace (E n)
inst✝ : ∀ (n : ℕ), DiscreteTopology (E n)
s : Set ((n : ℕ) → E n)
hs : IsClosed[Pi.topologicalSpace] s
hne : s.Nonempty
f : ((n : ℕ) → E n) → (n : ℕ) → E n := fun x ↦ if x ∈ s then x else ⋯.some
fs : ∀ x ∈ s, f x = x
x y : (n : ℕ) → E n
hxy : x ≠ y
hfxfy : f x ≠ f y
I2 : cylinder x (firstDiff x y) = cylinder y (firstDiff x y)
xs : x ∉ s
ys : y ∉ s
Ax : (s ∩ cylinder x (longestPrefix x s)).Nonempty
fx : f x = Ax.some
Ay : (s ∩ cylinder y (longestPrefix y s)).Nonempty
fy : f y = Ay.some
H : firstDiff x y ≤ longestPrefix x s ∧ firstDiff x y ≤ longestPrefix y s
⊢ firstDiff x y ≤ firstDiff (f x) (f y)

Tactic:
· have : cylinder x (longestPrefix x s) = cylinder y (longestPrefix y s) := by
            rcases H with H | H
            · exact cylinder_longestPrefix_eq_of_longestPrefix_lt_firstDiff hs hne H xs ys
            · symm
              rw [firstDiff_comm] at H
              exact cylinder_longestPrefix_eq_of_longestPrefix_lt_firstDiff hs hne H ys xs
          rw [fx, fy] at hfxfy
          apply (hfxfy _).elim
          congr

Goal state after:
case neg
E : ℕ → Type u_1
inst✝¹ : (n : ℕ) → TopologicalSpace (E n)
inst✝ : ∀ (n : ℕ), DiscreteTopology (E n)
s : Set ((n : ℕ) → E n)
hs : IsClosed[Pi.topologicalSpace] s
hne : s.Nonempty
f : ((n : ℕ) → E n) → (n : ℕ) → E n := fun x ↦ if x ∈ s then x else ⋯.some
fs : ∀ x ∈ s, f x = x
x y : (n : ℕ) → E n
hxy : x ≠ y
hfxfy : f x ≠ f y
I2 : cylinder x (firstDiff x y) = cylinder y (firstDiff x y)
xs : x ∉ s
ys : y ∉ s
Ax : (s ∩ cylinder x (longestPrefix x s)).Nonempty
fx : f x = Ax.some
Ay : (s ∩ cylinder y (longestPrefix y s)).Nonempty
fy : f y = Ay.some
H : firstDiff x y ≤ longestPrefix x s ∧ firstDiff x y ≤ longestPrefix y s
⊢ firstDiff x y ≤ firstDiff (f x) (f y)
Module: Mathlib.MeasureTheory.Measure.Count

Goal state before:
pp: α : Type u_1
inst✝ : MeasurableSpace α
a : α
ha : MeasurableSet {a}
⊢ (count {a}).toReal = 1

Tactic:
count_singleton' ha,

Goal state after:
α : Type u_1
inst✝ : MeasurableSpace α
a : α
ha : MeasurableSet {a}
⊢ ENNReal.toReal 1 = 1
Module: Mathlib.MeasureTheory.Measure.Dirac

Goal state before:
pp: case mp
α : Type u_1
inst✝ : MeasurableSpace α
x y : α
⊢ dirac x = dirac y → ∀ (A : Set α), MeasurableSet A → (x ∈ A ↔ y ∈ A)

Tactic:
intro h

Goal state after:
case mp
α : Type u_1
inst✝ : MeasurableSpace α
x y : α
h : dirac x = dirac y
⊢ ∀ (A : Set α), MeasurableSet A → (x ∈ A ↔ y ∈ A)
Module: Mathlib.MeasureTheory.Measure.Dirac

Goal state before:
pp: case mpr
α : Type u_1
inst✝ : MeasurableSpace α
x y : α
⊢ (∀ (A : Set α), MeasurableSet A → (x ∈ A ↔ y ∈ A)) → dirac x = dirac y

Tactic:
intro h

Goal state after:
case mpr
α : Type u_1
inst✝ : MeasurableSpace α
x y : α
h : ∀ (A : Set α), MeasurableSet A → (x ∈ A ↔ y ∈ A)
⊢ dirac x = dirac y
Module: Mathlib.MeasureTheory.Integral.Lebesgue.Countable

Goal state before:
pp: α : Type u_1
inst✝² : MeasurableSpace α
μ : Measure α
inst✝¹ : Countable α
inst✝ : MeasurableSingletonClass α
f : α → ℝ≥0∞
⊢ ∫⁻ (a : α), f a ∂μ = ∑' (a : α), f a * μ {a}

Tactic:
by
  conv_lhs => rw [← sum_smul_dirac μ, lintegral_sum_measure]
  congr 1 with a : 1
  simp [mul_comm]

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

Goal state before:
pp: ι : Type u_2
X : Type u_3
Y : ι → Type u_4
f : (i : ι) → X → Y i
x y : PiNatEmbed X Y f
hxy : x.ofPiNat = y.ofPiNat
⊢ x = y

Tactic:
cases x

Goal state after:
case toPiNat
ι : Type u_2
X : Type u_3
Y : ι → Type u_4
f : (i : ι) → X → Y i
y : PiNatEmbed X Y f
ofPiNat✝ : X
hxy : { ofPiNat := ofPiNat✝ }.ofPiNat = y.ofPiNat
⊢ { ofPiNat := ofPiNat✝ } = y
Module: Mathlib.MeasureTheory.Constructions.Polish.Basic

Goal state before:
pp: γ : Type u_3
β : Type u_4
inst✝⁵ : TopologicalSpace γ
inst✝⁴ : PolishSpace γ
inst✝³ : TopologicalSpace β
inst✝² : T2Space β
inst✝¹ : MeasurableSpace β
inst✝ : OpensMeasurableSpace β
f : γ → β
f_cont : Continuous[inst✝⁵, inst✝³] f
f_inj : Injective f
this✝ : UpgradedIsCompletelyMetrizableSpace γ := upgradeIsCompletelyMetrizable γ
b : Set (Set γ)
b_count : b.Countable
b_nonempty : ∅ ∉ b
hb : IsTopologicalBasis b
this : Encodable ↑b
A : Type (max 0 u_3) := { p // Disjoint ↑p.1 ↑p.2 }
q : A → Set β
hq1 : ∀ (p : A), f '' ↑(↑p).1 ⊆ q p
hq2 : ∀ (p : A), Disjoint (f '' ↑(↑p).2) (q p)
q_meas : ∀ (p : A), MeasurableSet (q p)
E : ↑b → Set β := fun s ↦ closure[inst✝³] (f '' ↑s) ∩ ⋂ t, ⋂ (ht : Disjoint ↑s ↑t), q ⟨(s, t), ht⟩ \ q ⟨(t, s), ⋯⟩
u : ℕ → ℝ
u_anti : StrictAnti u
u_pos : ∀ (n : ℕ), 0 < u n
u_lim : Tendsto u atTop (𝓝 0)
F : ℕ → Set β := fun n ↦ ⋃ s, ⋃ (_ : Bornology.IsBounded ↑s ∧ diam ↑s ≤ u n), E s
y : γ
n : ℕ
⊢ ∃ s ∈ b, y ∈ s ∧ s ⊆ ball y (u n / 2)

Tactic:
apply hb.mem_nhds_iff.1
      exact ball_mem_nhds _ (half_pos (u_pos n))

Goal state after:
Module: Mathlib.GroupTheory.Complement

Goal state before:
pp: case mp
G : Type u_1
inst✝ : Group G
K : Subgroup G
S : Set G
hSK : IsComplement S ↑K
g₁ g₂ : G
⊢ (hSK.equiv g₁).1 = (hSK.equiv g₂).1 → g₁⁻¹ * g₂ ∈ K

Tactic:
intro h

Goal state after:
case mp
G : Type u_1
inst✝ : Group G
K : Subgroup G
S : Set G
hSK : IsComplement S ↑K
g₁ g₂ : G
h : (hSK.equiv g₁).1 = (hSK.equiv g₂).1
⊢ g₁⁻¹ * g₂ ∈ K
Module: Mathlib.GroupTheory.Complement

Goal state before:
pp: case mpr
G : Type u_1
inst✝ : Group G
K : Subgroup G
S : Set G
hSK : IsComplement S ↑K
g₁ g₂ : G
⊢ g₁⁻¹ * g₂ ∈ K → (hSK.equiv g₁).1 = (hSK.equiv g₂).1

Tactic:
intro h

Goal state after:
case mpr
G : Type u_1
inst✝ : Group G
K : Subgroup G
S : Set G
hSK : IsComplement S ↑K
g₁ g₂ : G
h : g₁⁻¹ * g₂ ∈ K
⊢ (hSK.equiv g₁).1 = (hSK.equiv g₂).1
Module: Mathlib.GroupTheory.Complement

Goal state before:
pp: case mp
G : Type u_1
inst✝ : Group G
H : Subgroup G
T : Set G
hHT : IsComplement (↑H) T
g₁ g₂ : G
⊢ (hHT.equiv g₁).2 = (hHT.equiv g₂).2 → g₂ * g₁⁻¹ ∈ H

Tactic:
intro h

Goal state after:
case mp
G : Type u_1
inst✝ : Group G
H : Subgroup G
T : Set G
hHT : IsComplement (↑H) T
g₁ g₂ : G
h : (hHT.equiv g₁).2 = (hHT.equiv g₂).2
⊢ g₂ * g₁⁻¹ ∈ H
Module: Mathlib.GroupTheory.Complement

Goal state before:
pp: case mpr
G : Type u_1
inst✝ : Group G
H : Subgroup G
T : Set G
hHT : IsComplement (↑H) T
g₁ g₂ : G
⊢ g₂ * g₁⁻¹ ∈ H → (hHT.equiv g₁).2 = (hHT.equiv g₂).2

Tactic:
intro h

Goal state after:
case mpr
G : Type u_1
inst✝ : Group G
H : Subgroup G
T : Set G
hHT : IsComplement (↑H) T
g₁ g₂ : G
h : g₂ * g₁⁻¹ ∈ H
⊢ (hHT.equiv g₁).2 = (hHT.equiv g₂).2
Module: Mathlib.GroupTheory.Complement

Goal state before:
pp: case mp
G : Type u_1
inst✝ : Group G
S T : Set G
hST : IsComplement S T
g : G
h1 : 1 ∈ T
⊢ ↑(hST.equiv g).1 = g → g ∈ S

Tactic:
intro h

Goal state after:
case mp
G : Type u_1
inst✝ : Group G
S T : Set G
hST : IsComplement S T
g : G
h1 : 1 ∈ T
h : ↑(hST.equiv g).1 = g
⊢ g ∈ S
Module: Mathlib.GroupTheory.Complement

Goal state before:
pp: case mpr
G : Type u_1
inst✝ : Group G
S T : Set G
hST : IsComplement S T
g : G
h1 : 1 ∈ T
⊢ g ∈ S → ↑(hST.equiv g).1 = g

Tactic:
intro h

Goal state after:
case mpr
G : Type u_1
inst✝ : Group G
S T : Set G
hST : IsComplement S T
g : G
h1 : 1 ∈ T
h : g ∈ S
⊢ ↑(hST.equiv g).1 = g
Module: Mathlib.GroupTheory.Complement

Goal state before:
pp: case mp
G : Type u_1
inst✝ : Group G
S T : Set G
hST : IsComplement S T
g : G
h1 : 1 ∈ S
⊢ ↑(hST.equiv g).2 = g → g ∈ T

Tactic:
intro h

Goal state after:
case mp
G : Type u_1
inst✝ : Group G
S T : Set G
hST : IsComplement S T
g : G
h1 : 1 ∈ S
h : ↑(hST.equiv g).2 = g
⊢ g ∈ T
Module: Mathlib.GroupTheory.Complement

Goal state before:
pp: case mpr
G : Type u_1
inst✝ : Group G
S T : Set G
hST : IsComplement S T
g : G
h1 : 1 ∈ S
⊢ g ∈ T → ↑(hST.equiv g).2 = g

Tactic:
intro h

Goal state after:
case mpr
G : Type u_1
inst✝ : Group G
S T : Set G
hST : IsComplement S T
g : G
h1 : 1 ∈ S
h : g ∈ T
⊢ ↑(hST.equiv g).2 = g
Module: Mathlib.MeasureTheory.Measure.Regular

Goal state before:
pp: α : Type u_1
inst✝² : MeasurableSpace α
inst✝¹ : TopologicalSpace α
inst✝ : OpensMeasurableSpace α
μ : Measure α
s : ℕ → Set α
h : ∀ (n : ℕ), (μ.restrict (s n)).OuterRegular
h' : ∀ (n : ℕ), IsOpen[inst✝¹] (s n)
h'' : univ ⊆ ⋃ n, s n
r : ℝ≥0∞
hm : ∀ (n : ℕ), MeasurableSet (s n)
A : ℕ → Set α
hAm : ∀ (n : ℕ), MeasurableSet (A n)
hAs : ∀ (n : ℕ), A n ⊆ s n
hAd : Pairwise (Disjoint on A)
hA : MeasurableSet (⋃ n, A n)
hr : r > μ (⋃ n, A n)
HA : μ (⋃ n, A n) < ∞
δ : ℕ → ℝ≥0∞
δ0 : ∀ (i : ℕ), 0 < δ i
hδε : μ (⋃ n, A n) + ∑' (i : ℕ), δ i < r
n : ℕ
H₁ : ∀ (t : Set α), (μ.restrict (s n)) t = μ (t ∩ s n)
⊢ μ (A n ∩ s n) ≠ ∞

Tactic:
exact ((measure_mono (inter_subset_left.trans (subset_iUnion A n))).trans_lt HA).ne

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

Goal state before:
pp: α : Type u_1
β : Type u_2
γ : Type u_3
δ : Type u_4
inst✝³ : TopologicalSpace α
inst✝² : TopologicalSpace β
inst✝¹ : TopologicalSpace γ
inst✝ : TopologicalSpace δ
f : CocompactMap α β
f' : α → β
h : f' = ⇑f
⊢ Tendsto f' (cocompact α) (cocompact β)

Tactic:
by
    simp_rw [h]
    exact f.cocompact_tendsto'

Goal state after:
Module: Mathlib.MeasureTheory.Group.Measure

Goal state before:
pp: G : Type u_1
inst✝² : MeasurableSpace G
inst✝¹ : Mul G
inst✝ : MeasurableMul G
μ : Measure G
⊢ (∀ (g : G) (A : Set G), MeasurableSet A → μ ((fun h ↦ g * h) ⁻¹' A) = μ A) ↔
    ∀ (g : G), Measure.map (fun x ↦ g * x) μ = μ

Tactic:
simp_rw [Measure.ext_iff]

Goal state after:
G : Type u_1
inst✝² : MeasurableSpace G
inst✝¹ : Mul G
inst✝ : MeasurableMul G
μ : Measure G
⊢ (∀ (g : G) (A : Set G), MeasurableSet A → μ ((fun h ↦ g * h) ⁻¹' A) = μ A) ↔
    ∀ (g : G) (s : Set G), MeasurableSet s → (Measure.map (fun x ↦ g * x) μ) s = μ s
Module: Mathlib.MeasureTheory.Group.Measure

Goal state before:
pp: G : Type u_1
inst✝² : MeasurableSpace G
inst✝¹ : Mul G
inst✝ : MeasurableMul G
μ : Measure G
⊢ (∀ (g : G) (A : Set G), MeasurableSet A → μ ((fun h ↦ h * g) ⁻¹' A) = μ A) ↔
    ∀ (g : G), Measure.map (fun x ↦ x * g) μ = μ

Tactic:
simp_rw [Measure.ext_iff]

Goal state after:
G : Type u_1
inst✝² : MeasurableSpace G
inst✝¹ : Mul G
inst✝ : MeasurableMul G
μ : Measure G
⊢ (∀ (g : G) (A : Set G), MeasurableSet A → μ ((fun h ↦ h * g) ⁻¹' A) = μ A) ↔
    ∀ (g : G) (s : Set G), MeasurableSet s → (Measure.map (fun x ↦ x * g) μ) s = μ s