Some results on counting roots of polynomials and the Sylvester resultant.

International audience We present two results, the first on the distribution of the roots of a polynomial over the ring of integers modulo n and the second on the distribution of the roots of the Sylvester resultant of two multivariate polynomials. The second result has application to polynomial GCD computation and solving polynomial diophantine equations.

Approximate Gröbner Bases, Overdetermined Polynomial Systems, and Approximate GCDs

We discuss computation of Gröbner bases using approximate arithmetic for coefficients. We show how certain considerations of tolerance, corresponding roughly to absolute and relative error from numeric computation, allow us to obtain good approximate solutions to problems that are overdetermined. We provide examples of solving overdetermined systems of polynomial equations. As a secondary feature we show handling of approximate polynomial GCD computations, using benchmarks from the literature.

Polynomial GCD Derived through Monic Polynomial Subtractions

A simple and efficient algorithm for finding the GCD of a pair of univariate polynomials is derived. The process requires only successive subtraction of two monic polynomials. Amazingly, this approach gives the desired GCD for a pair of test polynomials of very high degree, such as and its derivative.