“…In case n = 2 this problem was solved by the famous Abhyankar-Moh theorem [1] which states that f is a coordinate if and only if I(∂ x f, ∂ y f ) = (1) and the curve defined by f = 0 has one place at infinity. Since then, various solutions have been given to this problem, see, e.g., [2][3][4][5]7,16,18]. For n 3 the problem remains open so far, and a well-known Conjecture of Abhyankar and Sathaye states that any time K[x]/f is K-isomorphic to K [n−1] , f is a coordinate in K [x].…”