calc
  lh s ≤ under (lh s) := le_under _
  _    ≤ 2 * s        := by simp [←hs.domain_eq]
case pos
M : Type u_1
inst✝⁵ : Zero M
inst✝⁴ : One M
inst✝³ : Add M
inst✝² : Mul M
inst✝¹ : LT M
inst✝ : M ⊧ₘ* 𝐈𝚺₁
s : M
hs : Seq s
⊢ lh s ≤ 2 * s
no goals