Theorem: algebra.lex_le_trans
Proof state before:
n : ℕ
v₁ v₂ v₃ : Variables n order.Lex
h₁ : Order.lex v₁ v₂
h₂ : Order.lex v₂ v₃
m : ℕ
a b c : Variables m order.Lex
x : ℕ
xs : List ℕ
p : List.length (x :: xs) = m
y : ℕ
ys : List ℕ
q : List.length (y :: ys) = m
z : ℕ
zs : List ℕ
l : List.length (z :: zs) = m
ab :
  match { val := x :: xs, property := p }, { val := y :: ys, property := q } with
  | { val := [], property := property }, { val := [], property := property_1 } => True
  | { val := x_1 :: tail, property := property }, { val := y_1 :: tail_1, property := property_1 } =>
    if x_1 = y_1 then
      Order.lex_impl (Vector.tail { val := x :: xs, property := p }) (Vector.tail { val := y :: ys, property := q })
    else x_1 ≤ y_1
bc :
  match { val := y :: ys, property := q }, { val := z :: zs, property := l } with
  | { val := [], property := property }, { val := [], property := property_1 } => True
  | { val := x :: tail, property := property }, { val := y_1 :: tail_1, property := property_1 } =>
    if x = y_1 then
      Order.lex_impl (Vector.tail { val := y :: ys, property := q }) (Vector.tail { val := z :: zs, property := l })
    else x ≤ y_1
⊢ match { val := x :: xs, property := p }, { val := z :: zs, property := l } with
  | { val := [], property := property }, { val := [], property := property_1 } => True
  | { val := x_1 :: tail, property := property }, { val := y :: tail_1, property := property_1 } =>
    if x_1 = y then
      Order.lex_impl (Vector.tail { val := x :: xs, property := p }) (Vector.tail { val := z :: zs, property := l })
    else x_1 ≤ y
Tactic:
split at ab
Proof state after:
case h_1
n : ℕ
v₁ v₂ v₃ : Variables n order.Lex
h₁ : Order.lex v₁ v₂
h₂ : Order.lex v₂ v₃
m : ℕ
a b c : Variables m order.Lex
x : ℕ
xs : List ℕ
p : List.length (x :: xs) = m
y : ℕ
ys : List ℕ
q : List.length (y :: ys) = m
z : ℕ
zs : List ℕ
l : List.length (z :: zs) = m
bc :
  match { val := y :: ys, property := q }, { val := z :: zs, property := l } with
  | { val := [], property := property }, { val := [], property := property_1 } => True
  | { val := x :: tail, property := property }, { val := y_1 :: tail_1, property := property_1 } =>
    if x = y_1 then
      Order.lex_impl (Vector.tail { val := y :: ys, property := q }) (Vector.tail { val := z :: zs, property := l })
    else x ≤ y_1
v₁✝ v₂✝ : Vector ℕ m
property✝¹ property✝ : List.length [] = m
heq✝¹ : { val := x :: xs, property := p } = { val := [], property := property✝¹ }
heq✝ : { val := y :: ys, property := q } = { val := [], property := property✝ }
ab : True
⊢ if x = z then Order.lex_impl (tail { val := x :: xs, property := p }) (tail { val := z :: zs, property := l })
  else x ≤ z

case h_2
n : ℕ
v₁ v₂ v₃ : Variables n order.Lex
h₁ : Order.lex v₁ v₂
h₂ : Order.lex v₂ v₃
m : ℕ
a b c : Variables m order.Lex
x : ℕ
xs : List ℕ
p : List.length (x :: xs) = m
y : ℕ
ys : List ℕ
q : List.length (y :: ys) = m
z : ℕ
zs : List ℕ
l : List.length (z :: zs) = m
bc :
  match { val := y :: ys, property := q }, { val := z :: zs, property := l } with
  | { val := [], property := property }, { val := [], property := property_1 } => True
  | { val := x :: tail, property := property }, { val := y_1 :: tail_1, property := property_1 } =>
    if x = y_1 then
      Order.lex_impl (Vector.tail { val := y :: ys, property := q }) (Vector.tail { val := z :: zs, property := l })
    else x ≤ y_1
v₁✝ v₂✝ : Vector ℕ m
x✝ : ℕ
tail✝¹ : List ℕ
property✝¹ : List.length (x✝ :: tail✝¹) = m
y✝ : ℕ
tail✝ : List ℕ
property✝ : List.length (y✝ :: tail✝) = m
heq✝¹ : { val := x :: xs, property := p } = { val := x✝ :: tail✝¹, property := property✝¹ }
heq✝ : { val := y :: ys, property := q } = { val := y✝ :: tail✝, property := property✝ }
ab :
  if x✝ = y✝ then Order.lex_impl (tail { val := x :: xs, property := p }) (tail { val := y :: ys, property := q })
  else x✝ ≤ y✝
⊢ if x = z then Order.lex_impl (tail { val := x :: xs, property := p }) (tail { val := z :: zs, property := l })
  else x ≤ z