On the reducibility and the lenticular sets of zeroes of almost Newman lacunary polynomials

Abstract

The class B of lacunary polynomials f(x) := -1 + x + x^n + x^{m_1} + x^{m_2} + ... + x^{m_s}, where s >= 0, m_1 - n >= n - 1, m_{q+1} - m_{q} >= n - 1 for 1 <= q < s, n >= 3 is studied. A polynomial having its coefficients in {0, 1} except its constant coefficient equal to -1 is called an almost Newman polynomial. A general theorem of factorization of the almost Newman polynomials of the class B is obtained. Such polynomials possess lenticular roots in the open unit disk off the unit circle in the small angular sector \pi/18 <= arg z <= \pi/18 and their nonreciprocal parts are always irreducible. The existence of lenticuli of roots is a peculiarity of the class B. By comparison with the Odlyzko - Poonen Conjecture and its variant Conjecture, an ``Asymptotic Reducibility Conjecture'' is formulated aiming at establishing the proportion of irreducible polynomials in this class. This proportion is conjectured to be 3/4 and estimated using Monte-Carlo methods. The numerical approximate value ~ 0.756 is obtained. The results extend those on trinomials (Selmer) and quadrinomials (Ljunggren, Mills, Finch and Jones).

Keywords

Bibliographic record

BibTeX Citation

@article{Dutykh2018reducibilitylenticular,
  author = {Dutykh, D. and Verger-Gaugry, J.-L.},
  title = {On the reducibility and the lenticular sets of zeroes of almost Newman lacunary polynomials},
  journal = {Arnold Mathematical Journal},
  year = {2018},
  volume = {4},
  number = {3-4},
  pages = {315--344},
  doi = {10.1007/s40598-019-00102-1},
  abstract = {The class B of lacunary polynomials f(x) := -1 + x + x^n + x^{m_1} + x^{m_2} + ... + x^{m_s}, where s >= 0, m_1 - n >= n - 1, m_{q+1} - m_{q} >= n - 1 for 1 <= q < s, n >= 3 is studied. A polynomial having its coefficients in {0, 1} except its constant coefficient equal to -1 is called an almost Newman polynomial. A general theorem of factorization of the almost Newman polynomials of the class B is obtained. Such polynomials possess lenticular roots in the open unit disk off the unit circle in the small angular sector \pi/18 <= arg z <= \pi/18 and their nonreciprocal parts are always irreducible. The existence of lenticuli of roots is a peculiarity of the class B. By comparison with the Odlyzko - Poonen Conjecture and its variant Conjecture, an ``Asymptotic Reducibility Conjecture'' is formulated aiming at establishing the proportion of irreducible polynomials in this class. This proportion is conjectured to be 3/4 and estimated using Monte-Carlo methods. The numerical approximate value ~ 0.756 is obtained. The results extend those on trinomials (Selmer) and quadrinomials (Ljunggren, Mills, Finch and Jones).},
  keywords = {Newman polynomial, Lenticular root, Reducibility, Lacunary polynomial, Almost Newman polynomial, ACM2012.G.1.3}
}