-- Mathlib/Analysis/BoxIntegral/Partition/SubboxInduction.lean
theorem exists_taggedPartition_isHenstock_isSubordinate_homothetic (I : Box ι)
    (r : (ι → ℝ) → Ioi (0 : ℝ)) :
    ∃ π : TaggedPrepartition I, π.IsPartition ∧ π.IsHenstock ∧ π.IsSubordinate r ∧
      (∀ J ∈ π, ∃ m : ℕ, ∀ i, (J :).upper i - J.lower i = (I.upper i - I.lower i) / 2 ^ m) ∧
        π.distortion = I.distortion

Proof state:
case refine_1
ι : Type u_1
inst✝ : Fintype ι
I : Box ι
r : (ι → ℝ) → ↑(Ioi 0)
J : Box ι
x✝ : J ≤ I
πi : (J' : Box ι) → TaggedPrepartition J'
hP✝ : ∀ J' ∈ splitCenter J, (πi J').IsPartition
hHen : ∀ J' ∈ splitCenter J, (πi J').IsHenstock
hr : ∀ J' ∈ splitCenter J, (πi J').IsSubordinate r
a✝ : ∀ J' ∈ splitCenter J, (πi J').distortion = J'.distortion
n : Box ι → Box ι → ℕ
hn : ∀ J' ∈ splitCenter J, ∀ J ∈ πi J', ∀ (i : ι), J.upper i - J.lower i = (J'.upper i - J'.lower i) / 2 ^ n J' J
hP : ((splitCenter J).biUnionTagged πi).IsPartition
hsub :
  ∀ J' ∈ (splitCenter J).biUnionTagged πi, ∃ n, ∀ (i : ι), J'.upper i - J'.lower i = (J.upper i - J.lower i) / 2 ^ n
⊢ ((splitCenter J).biUnionTagged πi).distortion = J.distortion

Tactic:
refine TaggedPrepartition.distortion_of_const _ hP.nonempty_boxes fun J' h' => ?_

Result:
case refine_1
ι : Type u_1
inst✝ : Fintype ι
I : Box ι
r : (ι → ℝ) → ↑(Ioi 0)
J : Box ι
x✝ : J ≤ I
πi : (J' : Box ι) → TaggedPrepartition J'
hP✝ : ∀ J' ∈ splitCenter J, (πi J').IsPartition
hHen : ∀ J' ∈ splitCenter J, (πi J').IsHenstock
hr : ∀ J' ∈ splitCenter J, (πi J').IsSubordinate r
a✝ : ∀ J' ∈ splitCenter J, (πi J').distortion = J'.distortion
n : Box ι → Box ι → ℕ
hn : ∀ J' ∈ splitCenter J, ∀ J ∈ πi J', ∀ (i : ι), J.upper i - J.lower i = (J'.upper i - J'.lower i) / 2 ^ n J' J
hP : ((splitCenter J).biUnionTagged πi).IsPartition
hsub :
  ∀ J' ∈ (splitCenter J).biUnionTagged πi, ∃ n, ∀ (i : ι), J'.upper i - J'.lower i = (J.upper i - J.lower i) / 2 ^ n
J' : Box ι
h' : J' ∈ (splitCenter J).biUnionTagged πi
⊢ J'.distortion = J.distortion

Proof state:
ι : Type u_1
inst✝ : Fintype ι
I : Box ι
r : (ι → ℝ) → ↑(Ioi 0)
J : Box ι
x✝ : J ≤ I
πi : (J' : Box ι) → TaggedPrepartition J'
hP✝ : ∀ J' ∈ splitCenter J, (πi J').IsPartition
hHen : ∀ J' ∈ splitCenter J, (πi J').IsHenstock
hr : ∀ J' ∈ splitCenter J, (πi J').IsSubordinate r
a✝ : ∀ J' ∈ splitCenter J, (πi J').distortion = J'.distortion
n : Box ι → Box ι → ℕ
hn : ∀ J' ∈ splitCenter J, ∀ J ∈ πi J', ∀ (i : ι), J.upper i - J.lower i = (J'.upper i - J'.lower i) / 2 ^ n J' J
hP : ((splitCenter J).biUnionTagged πi).IsPartition
⊢ ∀ J' ∈ (splitCenter J).biUnionTagged πi, ∃ n, ∀ (i : ι), J'.upper i - J'.lower i = (J.upper i - J.lower i) / 2 ^ n

Tactic:
intro J' hJ'

Result:
ι : Type u_1
inst✝ : Fintype ι
I : Box ι
r : (ι → ℝ) → ↑(Ioi 0)
J : Box ι
x✝ : J ≤ I
πi : (J' : Box ι) → TaggedPrepartition J'
hP✝ : ∀ J' ∈ splitCenter J, (πi J').IsPartition
hHen : ∀ J' ∈ splitCenter J, (πi J').IsHenstock
hr : ∀ J' ∈ splitCenter J, (πi J').IsSubordinate r
a✝ : ∀ J' ∈ splitCenter J, (πi J').distortion = J'.distortion
n : Box ι → Box ι → ℕ
hn : ∀ J' ∈ splitCenter J, ∀ J ∈ πi J', ∀ (i : ι), J.upper i - J.lower i = (J'.upper i - J'.lower i) / 2 ^ n J' J
hP : ((splitCenter J).biUnionTagged πi).IsPartition
J' : Box ι
hJ' : J' ∈ (splitCenter J).biUnionTagged πi
⊢ ∃ n, ∀ (i : ι), J'.upper i - J'.lower i = (J.upper i - J.lower i) / 2 ^ n

Proof state:
case refine_1
ι : Type u_1
inst✝ : Fintype ι
I : Box ι
r : (ι → ℝ) → ↑(Ioi 0)
J : Box ι
x✝ : J ≤ I
πi : (J' : Box ι) → TaggedPrepartition J'
hP✝ : ∀ J' ∈ splitCenter J, (πi J').IsPartition
hHen : ∀ J' ∈ splitCenter J, (πi J').IsHenstock
hr : ∀ J' ∈ splitCenter J, (πi J').IsSubordinate r
a✝ : ∀ J' ∈ splitCenter J, (πi J').distortion = J'.distortion
n : Box ι → Box ι → ℕ
hn : ∀ J' ∈ splitCenter J, ∀ J ∈ πi J', ∀ (i : ι), J.upper i - J.lower i = (J'.upper i - J'.lower i) / 2 ^ n J' J
hP : ((splitCenter J).biUnionTagged πi).IsPartition
hsub :
  ∀ J' ∈ (splitCenter J).biUnionTagged πi, ∃ n, ∀ (i : ι), J'.upper i - J'.lower i = (J.upper i - J.lower i) / 2 ^ n
⊢ ∃ π,
    π.IsPartition ∧
      π.IsHenstock ∧
        π.IsSubordinate r ∧
          (∀ J_1 ∈ π, ∃ m, ∀ (i : ι), J_1.upper i - J_1.lower i = (J.upper i - J.lower i) / 2 ^ m) ∧
            π.distortion = J.distortion

Tactic:
refine ⟨_, hP, isHenstock_biUnionTagged.2 hHen, isSubordinate_biUnionTagged.2 hr, hsub, ?_⟩

Result:
case refine_1
ι : Type u_1
inst✝ : Fintype ι
I : Box ι
r : (ι → ℝ) → ↑(Ioi 0)
J : Box ι
x✝ : J ≤ I
πi : (J' : Box ι) → TaggedPrepartition J'
hP✝ : ∀ J' ∈ splitCenter J, (πi J').IsPartition
hHen : ∀ J' ∈ splitCenter J, (πi J').IsHenstock
hr : ∀ J' ∈ splitCenter J, (πi J').IsSubordinate r
a✝ : ∀ J' ∈ splitCenter J, (πi J').distortion = J'.distortion
n : Box ι → Box ι → ℕ
hn : ∀ J' ∈ splitCenter J, ∀ J ∈ πi J', ∀ (i : ι), J.upper i - J.lower i = (J'.upper i - J'.lower i) / 2 ^ n J' J
hP : ((splitCenter J).biUnionTagged πi).IsPartition
hsub :
  ∀ J' ∈ (splitCenter J).biUnionTagged πi, ∃ n, ∀ (i : ι), J'.upper i - J'.lower i = (J.upper i - J.lower i) / 2 ^ n
⊢ ((splitCenter J).biUnionTagged πi).distortion = J.distortion

Proof state:
case refine_2
ι : Type u_1
inst✝ : Fintype ι
I : Box ι
r : (ι → ℝ) → ↑(Ioi 0)
z : ι → ℝ
x✝ : z ∈ Box.Icc I
J : Box ι
a✝ : J ≤ I
n : ℕ
Hmem : z ∈ Box.Icc J
HIcc : Box.Icc J ⊆ Box.Icc I ∧ Box.Icc J ⊆ closedBall z ↑(r z)
Hsub : ∀ (i : ι), J.upper i - J.lower i = (I.upper i - I.lower i) / 2 ^ n
⊢ ∃ m, ∀ (i : ι), J.upper i - J.lower i = (J.upper i - J.lower i) / 2 ^ m

Tactic:
refine ⟨0, fun i => ?_⟩

Result:
case refine_2
ι : Type u_1
inst✝ : Fintype ι
I : Box ι
r : (ι → ℝ) → ↑(Ioi 0)
z : ι → ℝ
x✝ : z ∈ Box.Icc I
J : Box ι
a✝ : J ≤ I
n : ℕ
Hmem : z ∈ Box.Icc J
HIcc : Box.Icc J ⊆ Box.Icc I ∧ Box.Icc J ⊆ closedBall z ↑(r z)
Hsub : ∀ (i : ι), J.upper i - J.lower i = (I.upper i - I.lower i) / 2 ^ n
i : ι
⊢ J.upper i - J.lower i = (J.upper i - J.lower i) / 2 ^ 0

Proof state:
case refine_2
ι : Type u_1
inst✝ : Fintype ι
I : Box ι
r : (ι → ℝ) → ↑(Ioi 0)
z : ι → ℝ
x✝ : z ∈ Box.Icc I
⊢ ∃ U ∈ 𝓝[Box.Icc I] z,
    ∀ J ≤ I,
      ∀ (m : ℕ),
        z ∈ Box.Icc J →
          Box.Icc J ⊆ U →
            (∀ (i : ι), J.upper i - J.lower i = (I.upper i - I.lower i) / 2 ^ m) →
              ∃ π,
                π.IsPartition ∧
                  π.IsHenstock ∧
                    π.IsSubordinate r ∧
                      (∀ J_1 ∈ π, ∃ m, ∀ (i : ι), J_1.upper i - J_1.lower i = (J.upper i - J.lower i) / 2 ^ m) ∧
                        π.distortion = J.distortion

Tactic:
refine ⟨Box.Icc I ∩ closedBall z (r z),
  inter_mem_nhdsWithin _ (closedBall_mem_nhds _ (r z).coe_prop), ?_⟩

Result:
case refine_2
ι : Type u_1
inst✝ : Fintype ι
I : Box ι
r : (ι → ℝ) → ↑(Ioi 0)
z : ι → ℝ
x✝ : z ∈ Box.Icc I
⊢ ∀ J ≤ I,
    ∀ (m : ℕ),
      z ∈ Box.Icc J →
        Box.Icc J ⊆ Box.Icc I ∩ closedBall z ↑(r z) →
          (∀ (i : ι), J.upper i - J.lower i = (I.upper i - I.lower i) / 2 ^ m) →
            ∃ π,
              π.IsPartition ∧
                π.IsHenstock ∧
                  π.IsSubordinate r ∧
                    (∀ J_1 ∈ π, ∃ m, ∀ (i : ι), J_1.upper i - J_1.lower i = (J.upper i - J.lower i) / 2 ^ m) ∧
                      π.distortion = J.distortion