Factoring Polynomials with Rational Coefficients.
We show how an old principle, due to Walsh (1922), can be used in order to construct an algorithm which finds the roots of polynomials with complex coefficients. This algorithm uses a linear command. From the very first step, the zero is located inside a disk, so several zeros can be searched at the same time.
We prove that there are only finitely many positive integers such that there is some integer such that is 1 or a prime for all , thus solving a problem of Byeon and Stark.
Soit un sous-groupe de rang maximal d’un corps de nombres . On montre qu’une fonction entière, envoyant dans l’anneau des entiers d’une extension finie de , de croissance analytique et arithmétique faibles est un polynôme. Ce résultat étend un théorème bien connu de Pólya. On montre également que ce résultat est à constante près optimal.