The disconnectedness of certain sets defined after uni-variate polynomials

被引:2
作者
Kostov, Vladimir Petrov [1 ]
机构
[1] Univ Cote Azur, Dept Math, CNRS, LJAD, Nice, France
来源
CONSTRUCTIVE MATHEMATICAL ANALYSIS | 2022年 / 5卷 / 03期
关键词
Real polynomial in one variable; hyperbolic polynomial; Descartes' rule of signs; discriminant set; DESCARTES RULE; SIGNS;
D O I
10.33205/cma.1111247
中图分类号
O1 [数学];
学科分类号
0701 ; 070101 ;
摘要
We consider the set of monic real uni-variate polynomials of a given degree d with non-vanishing coefficients, with given signs of the coefficients and with given quantities pos of their positive and neg of their negative roots (all roots are distinct). For d >= 6 and for signs of the coefficients (+, -, +, +, ... , +, +, -, +), we prove that the set of such polynomials having two positive, d - 4 negative and two complex conjugate roots, is not connected. For pos + neg <= 3 and for any d, we give the exhaustive answer to the question for which signs of the coefficients there exist polynomials with such values of pos and neg.
引用
收藏
页码:119 / 133
页数:15
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