theorem
HexRootsMathlib.remote_tail_le
{s : Multiset ℂ}
{d ρ : ℝ}
(hd : 0 < d)
(hρ : 0 ≤ ρ)
(hs : ∀ z ∈ s, d ≤ ‖z‖)
:
If every remote root has norm at least d, the normalized coefficient
tail is bounded by (1 + ρ / d)^n - 1. The next completeness layer connects
this elementary-symmetric data to the coefficients of the normalized product
∏ z, (1 - X / z).