Module: Mathlib.MeasureTheory.VectorMeasure.Decomposition.Hahn

Goal state before:
pp: case left
α : Type u_1
inst✝ : MeasurableSpace α
s : SignedMeasure α
i j : Set α
hi : MeasurableSet i
hj : MeasurableSet j
hi' : (∀ ⦃j : Set α⦄, MeasurableSet j → j ⊆ i → 0 j ≤ s j) ∧ ∀ ⦃j : Set α⦄, MeasurableSet j → j ⊆ iᶜ → s j ≤ 0 j
hj' :
  (∀ ⦃j_1 : Set α⦄, MeasurableSet j_1 → j_1 ⊆ j → 0 j_1 ≤ s j_1) ∧
    ∀ ⦃j_1 : Set α⦄, MeasurableSet j_1 → j_1 ⊆ jᶜ → s j_1 ≤ 0 j_1
⊢ s (jᶜ ∩ i) + 0 (iᶜ ∩ j) = 0

pp: case left.h
α : Type u_1
inst✝ : MeasurableSpace α
s : SignedMeasure α
i j : Set α
hi : MeasurableSet i
hj : MeasurableSet j
hi' : (∀ ⦃j : Set α⦄, MeasurableSet j → j ⊆ i → 0 j ≤ s j) ∧ ∀ ⦃j : Set α⦄, MeasurableSet j → j ⊆ iᶜ → s j ≤ 0 j
hj' :
  (∀ ⦃j_1 : Set α⦄, MeasurableSet j_1 → j_1 ⊆ j → 0 j_1 ≤ s j_1) ∧
    ∀ ⦃j_1 : Set α⦄, MeasurableSet j_1 → j_1 ⊆ jᶜ → s j_1 ≤ 0 j_1
⊢ Disjoint (jᶜ ∩ i) (iᶜ ∩ j)

pp: case left.hA
α : Type u_1
inst✝ : MeasurableSpace α
s : SignedMeasure α
i j : Set α
hi : MeasurableSet i
hj : MeasurableSet j
hi' : (∀ ⦃j : Set α⦄, MeasurableSet j → j ⊆ i → 0 j ≤ s j) ∧ ∀ ⦃j : Set α⦄, MeasurableSet j → j ⊆ iᶜ → s j ≤ 0 j
hj' :
  (∀ ⦃j_1 : Set α⦄, MeasurableSet j_1 → j_1 ⊆ j → 0 j_1 ≤ s j_1) ∧
    ∀ ⦃j_1 : Set α⦄, MeasurableSet j_1 → j_1 ⊆ jᶜ → s j_1 ≤ 0 j_1
⊢ MeasurableSet (jᶜ ∩ i)

pp: case left.hB
α : Type u_1
inst✝ : MeasurableSpace α
s : SignedMeasure α
i j : Set α
hi : MeasurableSet i
hj : MeasurableSet j
hi' : (∀ ⦃j : Set α⦄, MeasurableSet j → j ⊆ i → 0 j ≤ s j) ∧ ∀ ⦃j : Set α⦄, MeasurableSet j → j ⊆ iᶜ → s j ≤ 0 j
hj' :
  (∀ ⦃j_1 : Set α⦄, MeasurableSet j_1 → j_1 ⊆ j → 0 j_1 ≤ s j_1) ∧
    ∀ ⦃j_1 : Set α⦄, MeasurableSet j_1 → j_1 ⊆ jᶜ → s j_1 ≤ 0 j_1
⊢ MeasurableSet (iᶜ ∩ j)

Tactic:
le_antisymm (hj'.2 (hj.compl.inter hi) Set.inter_subset_left)
        (hi'.1 (hj.compl.inter hi) Set.inter_subset_right),

Goal state after:
case left
α : Type u_1
inst✝ : MeasurableSpace α
s : SignedMeasure α
i j : Set α
hi : MeasurableSet i
hj : MeasurableSet j
hi' : (∀ ⦃j : Set α⦄, MeasurableSet j → j ⊆ i → 0 j ≤ s j) ∧ ∀ ⦃j : Set α⦄, MeasurableSet j → j ⊆ iᶜ → s j ≤ 0 j
hj' :
  (∀ ⦃j_1 : Set α⦄, MeasurableSet j_1 → j_1 ⊆ j → 0 j_1 ≤ s j_1) ∧
    ∀ ⦃j_1 : Set α⦄, MeasurableSet j_1 → j_1 ⊆ jᶜ → s j_1 ≤ 0 j_1
⊢ 0 (jᶜ ∩ i) + 0 (iᶜ ∩ j) = 0

case left.h
α : Type u_1
inst✝ : MeasurableSpace α
s : SignedMeasure α
i j : Set α
hi : MeasurableSet i
hj : MeasurableSet j
hi' : (∀ ⦃j : Set α⦄, MeasurableSet j → j ⊆ i → 0 j ≤ s j) ∧ ∀ ⦃j : Set α⦄, MeasurableSet j → j ⊆ iᶜ → s j ≤ 0 j
hj' :
  (∀ ⦃j_1 : Set α⦄, MeasurableSet j_1 → j_1 ⊆ j → 0 j_1 ≤ s j_1) ∧
    ∀ ⦃j_1 : Set α⦄, MeasurableSet j_1 → j_1 ⊆ jᶜ → s j_1 ≤ 0 j_1
⊢ Disjoint (jᶜ ∩ i) (iᶜ ∩ j)

case left.hA
α : Type u_1
inst✝ : MeasurableSpace α
s : SignedMeasure α
i j : Set α
hi : MeasurableSet i
hj : MeasurableSet j
hi' : (∀ ⦃j : Set α⦄, MeasurableSet j → j ⊆ i → 0 j ≤ s j) ∧ ∀ ⦃j : Set α⦄, MeasurableSet j → j ⊆ iᶜ → s j ≤ 0 j
hj' :
  (∀ ⦃j_1 : Set α⦄, MeasurableSet j_1 → j_1 ⊆ j → 0 j_1 ≤ s j_1) ∧
    ∀ ⦃j_1 : Set α⦄, MeasurableSet j_1 → j_1 ⊆ jᶜ → s j_1 ≤ 0 j_1
⊢ MeasurableSet (jᶜ ∩ i)

case left.hB
α : Type u_1
inst✝ : MeasurableSpace α
s : SignedMeasure α
i j : Set α
hi : MeasurableSet i
hj : MeasurableSet j
hi' : (∀ ⦃j : Set α⦄, MeasurableSet j → j ⊆ i → 0 j ≤ s j) ∧ ∀ ⦃j : Set α⦄, MeasurableSet j → j ⊆ iᶜ → s j ≤ 0 j
hj' :
  (∀ ⦃j_1 : Set α⦄, MeasurableSet j_1 → j_1 ⊆ j → 0 j_1 ≤ s j_1) ∧
    ∀ ⦃j_1 : Set α⦄, MeasurableSet j_1 → j_1 ⊆ jᶜ → s j_1 ≤ 0 j_1
⊢ MeasurableSet (iᶜ ∩ j)