simp_arith
case right
α : Type
inst✝¹ : LE α
inst✝ : DecidableRel LE.le
x y : α
zs : List α
a b : α
cs : List α
helper : List.length (split cs).fst ≤ List.length cs ∧ List.length (split cs).snd ≤ List.length cs
⊢ List.length cs ≤ List.length cs + 1
no goals