Theorem: Batteries.RBNode.Ordered.append
File: .lake/packages/batteries/Batteries/Data/RBMap/WF.lean

Proof steps:
state_before: α : Type u_1
cmp : α → α → Ordering
l : RBNode α
v : α
r : RBNode α
lv : All (fun x => cmpLT cmp x v) l
vr : All (fun x => cmpLT cmp v x) r
hl : Ordered cmp l
hr : Ordered cmp r
⊢ Ordered cmp (l.append r)
state_after: α : Type u_1
cmp : α → α → Ordering
l : RBNode α
v : α
r : RBNode α
lv : All (fun x => cmpLT cmp x v) l
vr : All (fun x => cmpLT cmp v x) r
hl : Ordered cmp l
hr : Ordered cmp r
⊢ Ordered cmp
    (match l, r with
    | nil, x => x
    | x, nil => x
    | node red a x b, node red c y d =>
      match b.append c with
      | node red b' z c' => node red (node red a x b') z (node red c' y d)
      | bc => node red a x (node red bc y d)
    | node black a x b, node black c y d =>
      match b.append c with
      | node red b' z c' => node red (node black a x b') z (node black c' y d)
      | bc => a.balLeft x (node black bc y d)
    | a@h:(node black l v r), node red b x c => node red (a.append b) x c
    | node red a x b, c@h:(node black l v r) => node red a x (b.append c))
tactic: unfold append
state_before: α : Type u_1
cmp : α → α → Ordering
l : RBNode α
v : α
r : RBNode α
lv : All (fun x => cmpLT cmp x v) l
vr : All (fun x => cmpLT cmp v x) r
hl : Ordered cmp l
hr : Ordered cmp r
⊢ Ordered cmp
    (match l, r with
    | nil, x => x
    | x, nil => x
    | node red a x b, node red c y d =>
      match b.append c with
      | node red b' z c' => node red (node red a x b') z (node red c' y d)
      | bc => node red a x (node red bc y d)
    | node black a x b, node black c y d =>
      match b.append c with
      | node red b' z c' => node red (node black a x b') z (node black c' y d)
      | bc => a.balLeft x (node black bc y d)
    | a@h:(node black l v r), node red b x c => node red (a.append b) x c
    | node red a x b, c@h:(node black l v r) => node red a x (b.append c))
state_after: case h_1
α : Type u_1
cmp : α → α → Ordering
v : α
r : RBNode α
vr : All (fun x => cmpLT cmp v x) r
hr : Ordered cmp r
x✝¹ x✝ : RBNode α
lv : All (fun x => cmpLT cmp x v) nil
hl : Ordered cmp nil
⊢ Ordered cmp r

case h_2
α : Type u_1
cmp : α → α → Ordering
l : RBNode α
v : α
lv : All (fun x => cmpLT cmp x v) l
hl : Ordered cmp l
x✝² x✝¹ : RBNode α
x✝ : l = nil → False
vr : All (fun x => cmpLT cmp v x) nil
hr : Ordered cmp nil
⊢ Ordered cmp l

case h_3
α : Type u_1
cmp : α → α → Ordering
v : α
x✝² x✝¹ a✝ : RBNode α
x✝ : α
b✝ c✝ : RBNode α
y✝ : α
d✝ : RBNode α
lv : All (fun x => cmpLT cmp x v) (node red a✝ x✝ b✝)
hl : Ordered cmp (node red a✝ x✝ b✝)
vr : All (fun x => cmpLT cmp v x) (node red c✝ y✝ d✝)
hr : Ordered cmp (node red c✝ y✝ d✝)
⊢ Ordered cmp
    (match b✝.append c✝ with
    | node red b' z c' => node red (node red a✝ x✝ b') z (node red c' y✝ d✝)
    | bc => node red a✝ x✝ (node red bc y✝ d✝))

case h_4
α : Type u_1
cmp : α → α → Ordering
v : α
x✝² x✝¹ a✝ : RBNode α
x✝ : α
b✝ c✝ : RBNode α
y✝ : α
d✝ : RBNode α
lv : All (fun x => cmpLT cmp x v) (node black a✝ x✝ b✝)
hl : Ordered cmp (node black a✝ x✝ b✝)
vr : All (fun x => cmpLT cmp v x) (node black c✝ y✝ d✝)
hr : Ordered cmp (node black c✝ y✝ d✝)
⊢ Ordered cmp
    (match b✝.append c✝ with
    | node red b' z c' => node red (node black a✝ x✝ b') z (node black c' y✝ d✝)
    | bc => a✝.balLeft x✝ (node black bc y✝ d✝))

case h_5
α : Type u_1
cmp : α → α → Ordering
v : α
x✝² x✝¹ l✝ : RBNode α
v✝ : α
r✝ b✝ : RBNode α
x✝ : α
c✝ : RBNode α
lv : All (fun x => cmpLT cmp x v) (node black l✝ v✝ r✝)
hl : Ordered cmp (node black l✝ v✝ r✝)
vr : All (fun x => cmpLT cmp v x) (node red b✝ x✝ c✝)
hr : Ordered cmp (node red b✝ x✝ c✝)
⊢ Ordered cmp (node red ((node black l✝ v✝ r✝).append b✝) x✝ c✝)

case h_6
α : Type u_1
cmp : α → α → Ordering
v : α
x✝² x✝¹ a✝ : RBNode α
x✝ : α
b✝ l✝ : RBNode α
v✝ : α
r✝ : RBNode α
lv : All (fun x => cmpLT cmp x v) (node red a✝ x✝ b✝)
hl : Ordered cmp (node red a✝ x✝ b✝)
vr : All (fun x => cmpLT cmp v x) (node black l✝ v✝ r✝)
hr : Ordered cmp (node black l✝ v✝ r✝)
⊢ Ordered cmp (node red a✝ x✝ (b✝.append (node black l✝ v✝ r✝)))
tactic: split