fact: Definition ac_is_zero α {R : ring α} {K : field R} {acf : algeb_closed_field K} (x : α) := if fld_zerop x then True else False.
imports: Utf8 QArith NPeano ArithRing Misc Field2 ConvexHull Newton Fsummation Fpolynomial Puiseux_base Puiseux_series CharactPolyn