α : Type u_1
inst✝² : GeneralizedBooleanAlgebra α
inst✝¹ : DecidableRel Disjoint
inst✝ : DecidableRel fun x x_1 => x ≤ x_1
s : Finset α
u✝ v✝ a✝ b u v a : α
⊢ (if
        Disjoint u (if Disjoint u a ∧ v ≤ a then (a ⊔ u) \ v else a) ∧
          v ≤ if Disjoint u a ∧ v ≤ a then (a ⊔ u) \ v else a then
      ((if Disjoint u a ∧ v ≤ a then (a ⊔ u) \ v else a) ⊔ u) \ v
    else if Disjoint u a ∧ v ≤ a then (a ⊔ u) \ v else a) =
    if Disjoint u a ∧ v ≤ a then (a ⊔ u) \ v else a
α : Type u_1
inst✝² : GeneralizedBooleanAlgebra α
inst✝¹ : DecidableRel Disjoint
inst✝ : DecidableRel fun x x_1 => x ≤ x_1
s : Finset α
u✝ v✝ a✝ b u v a : α
⊢ compress u v (compress u v a) = compress u v a
unfold compress
case inl.inl
α : Type u_1
inst✝² : GeneralizedBooleanAlgebra α
inst✝¹ : DecidableRel Disjoint
inst✝ : DecidableRel fun x x_1 => x ≤ x_1
s : Finset α
u✝ v✝ a✝ b u v a : α
h : Disjoint u a ∧ v ≤ a
h' : Disjoint u ((a ⊔ u) \ v) ∧ v ≤ (a ⊔ u) \ v
⊢ ((a ⊔ u) \ v ⊔ u) \ v = (a ⊔ u) \ v
α : Type u_1
inst✝² : GeneralizedBooleanAlgebra α
inst✝¹ : DecidableRel Disjoint
inst✝ : DecidableRel fun x x_1 => x ≤ x_1
s : Finset α
u✝ v✝ a✝ b u v a : α
⊢ (if
        Disjoint u (if Disjoint u a ∧ v ≤ a then (a ⊔ u) \ v else a) ∧
          v ≤ if Disjoint u a ∧ v ≤ a then (a ⊔ u) \ v else a then
      ((if Disjoint u a ∧ v ≤ a then (a ⊔ u) \ v else a) ⊔ u) \ v
    else if Disjoint u a ∧ v ≤ a then (a ⊔ u) \ v else a) =
    if Disjoint u a ∧ v ≤ a then (a ⊔ u) \ v else a
split_ifs with h h' <;> try rfl
no goals
case inl.inl
α : Type u_1
inst✝² : GeneralizedBooleanAlgebra α
inst✝¹ : DecidableRel Disjoint
inst✝ : DecidableRel fun x x_1 => x ≤ x_1
s : Finset α
u✝ v✝ a✝ b u v a : α
h : Disjoint u a ∧ v ≤ a
h' : Disjoint u ((a ⊔ u) \ v) ∧ v ≤ (a ⊔ u) \ v
⊢ ((a ⊔ u) \ v ⊔ u) \ v = (a ⊔ u) \ v
rw [le_sdiff_iff.1 h'.2, sdiff_bot, sdiff_bot, sup_assoc, sup_idem]
no goals
case inr
α : Type u_1
inst✝² : GeneralizedBooleanAlgebra α
inst✝¹ : DecidableRel Disjoint
inst✝ : DecidableRel fun x x_1 => x ≤ x_1
s : Finset α
u✝ v✝ a✝ b u v a : α
h : ¬(Disjoint u a ∧ v ≤ a)
⊢ a = a
rfl