The calculation of multivariate polynomial resultant

Abstract

An efficient algorithm is presented for the exact calculation of resultants of multivariate polynomials with integer coefficients. The algorithm applies modular homomorphisms and the Chinese remainder theorem, evaluation homomorphisms and interpolation, in reducing the problem to resultant calculation for univariate polynomials over GF(p), whereupon a polynomial remainder sequence algorithm is used. The computing time of the algorithm is analyzed theoretically as a function of the degrees and coefficient sizes of its inputs. As a very special case, it is shown that when all degrees are equal and the coefficient size is fixed, its computing time is approximately proportional to λ 2r+l , where λ is the common degree and r is the number of variables. Empirically observed computing times of the algorithm are tabulated for a large number of examples, and other algorithms are compared. Potential application of the algorithm to the solution of systems of polynomial equations is briefly discussed.