A polynomial-time reduction from bivariate to univariate integral polynomial factorization

An algorithm is presented which reduces the problem of finding the irreducible factors of a bivariate polynomial with integer coefficients in polynomial time in the total degree and the coefficient lengths to factoring a univariate integer polynomial. Together with A. Lenstra's, H. Lenstra's and L. Lovasz' polynomial-time factorization algorithm for univariate integer polynomials and the author's multivariate to bivariate reduction the new algorithm implies the following theorem. Factoring a polynomial with a fixed number of variables into irreducibles, except for the constant factors, can be accomplished in time polynomial in the total degree and the size of its coefficients. The new algorithm can be generalized to reducing multivariate factorization directly to univariate factorization and to factoring multivariate polynomials with coefficients in algebraic number fields and finite fields in polynomial time.