TY - JOUR

T1 - On μ-symmetric polynomials

AU - Yang, Jing

AU - Yap, Chee K.

N1 - Publisher Copyright:
© 2022 World Scientific Publishing Company.

PY - 2021

Y1 - 2021

N2 - We study functions of the roots of an integer polynomial p = p(x) with m ≥ 2 distinct roots = (1,.,m) of multiplicity μ = (μ1,.,μm), μ1 ≥⋯ ≥ μm ≥ 1. Traditionally, root functions are studied via the theory of symmetric polynomials; we generalize this theory to μ-symmetric polynomials. We initiate the study of the vector space of μ-symmetric polynomials of a given degree via the concepts of μ-gist and μ-ideal. In particular, we are interested in the root function Dμ+(r 1,.,rm)a1ijm(ri-rj)μi+μj. The D-plus discriminant of p is D+(p)D μ+( 1,.,m). This quantity appears in the complexity analysis of the root clustering algorithm of Becker et al. (ISSAC 2016). We conjecture that Dμ+(r 1.rm) is μ-symmetric, which implies D+(p) is rational. To explore this conjecture experimentally, we introduce algorithms for checking if a given root function is μ-symmetric. We design three such algorithms: one based on Gröbner bases, another based on canonical bases and reduction, and the third based on solving linear equations. Each of these algorithms has variants that depend on the choice of a basis for the μ-symmetric functions. We implement these algorithms (and their variants) in Maple and experiments show that the latter two algorithms are significantly faster than the first.

AB - We study functions of the roots of an integer polynomial p = p(x) with m ≥ 2 distinct roots = (1,.,m) of multiplicity μ = (μ1,.,μm), μ1 ≥⋯ ≥ μm ≥ 1. Traditionally, root functions are studied via the theory of symmetric polynomials; we generalize this theory to μ-symmetric polynomials. We initiate the study of the vector space of μ-symmetric polynomials of a given degree via the concepts of μ-gist and μ-ideal. In particular, we are interested in the root function Dμ+(r 1,.,rm)a1ijm(ri-rj)μi+μj. The D-plus discriminant of p is D+(p)D μ+( 1,.,m). This quantity appears in the complexity analysis of the root clustering algorithm of Becker et al. (ISSAC 2016). We conjecture that Dμ+(r 1.rm) is μ-symmetric, which implies D+(p) is rational. To explore this conjecture experimentally, we introduce algorithms for checking if a given root function is μ-symmetric. We design three such algorithms: one based on Gröbner bases, another based on canonical bases and reduction, and the third based on solving linear equations. Each of these algorithms has variants that depend on the choice of a basis for the μ-symmetric functions. We implement these algorithms (and their variants) in Maple and experiments show that the latter two algorithms are significantly faster than the first.

KW - D-plus discriminant

KW - gist polynomial

KW - lift polynomial

KW - multiple roots

KW - symmetric function

KW - μ-ideal

KW - μ-symmetric polynomial

UR - http://www.scopus.com/inward/record.url?scp=85116819729&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=85116819729&partnerID=8YFLogxK

U2 - 10.1142/S0219498822502334

DO - 10.1142/S0219498822502334

M3 - Article

AN - SCOPUS:85116819729

JO - Journal of Algebra and Its Applications

JF - Journal of Algebra and Its Applications

SN - 0219-4988

ER -