Module: Mathlib.Analysis.BoxIntegral.Basic

Goal state before:
pp: case hbc
ι : Type u
E : Type v
inst✝⁴ : NormedAddCommGroup E
inst✝³ : NormedSpace ℝ E
inst✝² : Fintype ι
l : IntegrationParams
inst✝¹ : CompleteSpace E
I : Box ι
f : (ι → ℝ) → E
μ : Measure (ι → ℝ)
inst✝ : IsLocallyFiniteMeasure μ
hc : ∀ᵐ (x : ι → ℝ) ∂μ.restrict (Box.Icc I), ContinuousWithinAt f (Box.Icc I) x
ε : ℝ
ε0 : ε > 0
ε₁ : ℝ
ε₁0 : 0 < ε₁
hε₁ : 2 * μ.toBoxAdditive I * ε₁ < ε
C : ℝ
hC : ∀ x ∈ Box.Icc I, ‖f x‖ ≤ C
C0 : 0 ≤ C
ε₂ : ℝ
ε₂0 : 0 < ε₂
hε₂ : 4 * C * ε₂ < ε
ε₂0' : ENNReal.ofReal ε₂ ≠ 0
D : Set (ι → ℝ) := {x | x ∈ Box.Icc I ∧ ¬ContinuousWithinAt f (Box.Icc I) x}
μ' : Measure (ι → ℝ) := μ.restrict (Box.Icc I)
μ'D : μ' D = 0
U : Set (ι → ℝ)
UD : U ⊇ D
Uopen : IsOpen U
hU : μ' U < ENNReal.ofReal ε₂
comp : IsCompact (Box.Icc I \ U)
this : ∀ x ∈ Box.Icc I \ U, oscillationWithin f (Box.Icc I) x < ENNReal.ofReal ε₁
r : ℝ
r0 : r > 0
hr : ∀ x ∈ Box.Icc I \ U, ediam (f '' (eball x (ENNReal.ofReal r) ∩ Box.Icc I)) ≤ ENNReal.ofReal ε₁
c₁ c₂ : ℝ≥0
π₁ π₂ : TaggedPrepartition I
h₁ : l.MemBaseSet I c₁ ((fun x x_1 ↦ ⟨r / 2, ⋯⟩) c₁) π₁
h₁p : π₁.IsPartition
h₂ : l.MemBaseSet I c₂ ((fun x x_1 ↦ ⟨r / 2, ⋯⟩) c₂) π₂
h₂p : π₂.IsPartition
μI : μ ↑I < ∞
t₁ : Box ι → ι → ℝ := fun J ↦ (π₁.infPrepartition π₂.toPrepartition).tag J
t₂ : Box ι → ι → ℝ := fun J ↦ (π₂.infPrepartition π₁.toPrepartition).tag J
B : Finset (Box ι) := (π₁.toPrepartition ⊓ π₂.toPrepartition).boxes
B' : Finset (Box ι) := {J ∈ B | ↑J ⊆ U}
hB' : B' ⊆ B
μJ_ne_top : ∀ J ∈ B, μ ↑J ≠ ∞
un : ∀ S ⊆ B, ⋃ J ∈ S, ↑J ⊆ ↑I
J : Box ι
hJ : J ∈ B ∧ (J ∈ B → ¬↑J ⊆ U)
x : ι → ℝ
xJ : x ∈ J
xnU : x ∉ U
hx : x ∈ Box.Icc I \ U
⊢ ‖f (t₁ J) - f (t₂ J)‖ ≤ ε₁

Tactic:
have ineq : edist (f (t₁ J)) (f (t₂ J)) ≤ ediam (f '' (ball x r ∩ (Box.Icc I))) := by
        apply edist_le_ediam_of_mem <;>
          refine Set.mem_image_of_mem f ⟨?_, tag_mem_Icc _ J⟩ <;>
          refine closedBall_subset_ball (div_two_lt_of_pos r0) <| mem_closedBall_comm.1 ?_
        · exact h₁.isSubordinate.infPrepartition π₂.toPrepartition J hJ.1 (Box.coe_subset_Icc xJ)
        · exact h₂.isSubordinate.infPrepartition π₁.toPrepartition J
            ((π₁.mem_infPrepartition_comm).1 hJ.1) (Box.coe_subset_Icc xJ)

Goal state after:
case hbc
ι : Type u
E : Type v
inst✝⁴ : NormedAddCommGroup E
inst✝³ : NormedSpace ℝ E
inst✝² : Fintype ι
l : IntegrationParams
inst✝¹ : CompleteSpace E
I : Box ι
f : (ι → ℝ) → E
μ : Measure (ι → ℝ)
inst✝ : IsLocallyFiniteMeasure μ
hc : ∀ᵐ (x : ι → ℝ) ∂μ.restrict (Box.Icc I), ContinuousWithinAt f (Box.Icc I) x
ε : ℝ
ε0 : ε > 0
ε₁ : ℝ
ε₁0 : 0 < ε₁
hε₁ : 2 * μ.toBoxAdditive I * ε₁ < ε
C : ℝ
hC : ∀ x ∈ Box.Icc I, ‖f x‖ ≤ C
C0 : 0 ≤ C
ε₂ : ℝ
ε₂0 : 0 < ε₂
hε₂ : 4 * C * ε₂ < ε
ε₂0' : ENNReal.ofReal ε₂ ≠ 0
D : Set (ι → ℝ) := {x | x ∈ Box.Icc I ∧ ¬ContinuousWithinAt f (Box.Icc I) x}
μ' : Measure (ι → ℝ) := μ.restrict (Box.Icc I)
μ'D : μ' D = 0
U : Set (ι → ℝ)
UD : U ⊇ D
Uopen : IsOpen U
hU : μ' U < ENNReal.ofReal ε₂
comp : IsCompact (Box.Icc I \ U)
this : ∀ x ∈ Box.Icc I \ U, oscillationWithin f (Box.Icc I) x < ENNReal.ofReal ε₁
r : ℝ
r0 : r > 0
hr : ∀ x ∈ Box.Icc I \ U, ediam (f '' (eball x (ENNReal.ofReal r) ∩ Box.Icc I)) ≤ ENNReal.ofReal ε₁
c₁ c₂ : ℝ≥0
π₁ π₂ : TaggedPrepartition I
h₁ : l.MemBaseSet I c₁ ((fun x x_1 ↦ ⟨r / 2, ⋯⟩) c₁) π₁
h₁p : π₁.IsPartition
h₂ : l.MemBaseSet I c₂ ((fun x x_1 ↦ ⟨r / 2, ⋯⟩) c₂) π₂
h₂p : π₂.IsPartition
μI : μ ↑I < ∞
t₁ : Box ι → ι → ℝ := fun J ↦ (π₁.infPrepartition π₂.toPrepartition).tag J
t₂ : Box ι → ι → ℝ := fun J ↦ (π₂.infPrepartition π₁.toPrepartition).tag J
B : Finset (Box ι) := (π₁.toPrepartition ⊓ π₂.toPrepartition).boxes
B' : Finset (Box ι) := {J ∈ B | ↑J ⊆ U}
hB' : B' ⊆ B
μJ_ne_top : ∀ J ∈ B, μ ↑J ≠ ∞
un : ∀ S ⊆ B, ⋃ J ∈ S, ↑J ⊆ ↑I
J : Box ι
hJ : J ∈ B ∧ (J ∈ B → ¬↑J ⊆ U)
x : ι → ℝ
xJ : x ∈ J
xnU : x ∉ U
hx : x ∈ Box.Icc I \ U
ineq : edist (f (t₁ J)) (f (t₂ J)) ≤ ediam (f '' (Metric.ball x r ∩ Box.Icc I))
⊢ ‖f (t₁ J) - f (t₂ J)‖ ≤ ε₁