rw [Function.minimalPeriod]
case left.hm
a b : ℕ
heq : next^[a] (0, 0) = next^[b] (0, 0)
⊢ a < Function.minimalPeriod next (0, 0)
case left.hm
a b : ℕ
heq : next^[a] (0, 0) = next^[b] (0, 0)
⊢ a < if h : (0, 0) ∈ Function.periodicPts next then Nat.find h else 0