fact: Definition one_root2 {R : archiFieldType} (p : {poly R}) (a : R) := exists c k : R, [/\ a < c, 0 < k, (forall x, a < x -> x <= c -> p.[x] < 0) & (forall x y, c <= x -> x < y -> k * (y - x) <= p.[y] - p.[x])]%R.
imports: mathcomp(all_ssreflect all_algebra) pol desc