Before revision: We show that, except for a special family of polynomials -that we call \lambda -reducible-, a natural  generalization of Schwartz-Zippel-DeMillo-Lipton lemma holds.
After revision: We show that, except for a special family of polynomials -that we call \lambda -reducible-, a natural generalization of Schwartz-Zippel-DeMillo-Lipton lemma holds.