The conjecture for sums of powers of quadratic polynomials

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Let nn be a positive integer, and let QPn\mathcal{QP}_n be the set of all nonidentically vanishing rational functions

f(x)=∑i=1nciPiα(x),f(x)=\sum_{i=1}^{n}c_{i}P_i^{\alpha}(x),

where ci∈Rc_i\in\mathbb{R}, α≤−1\alpha\leq -1 is real, and P1,…,PnP_1,\ldots,P_n are monic quadratic polynomials with real coefficients and no real zeros. Let Gf\mathcal{G}_f denote the garden of the real rational function ff.

Conjecture for sums of powers of quadratic polynomials. If f∈QPnf\in\mathcal{QP}_n, then ff has at most 2n−12n-1 real critical points. Moreover, if α\alpha is a negative integer, each chord of Gf\mathcal{G}_f contains at least one nonreal zero of ∏i=1nPi(x)\prod_{i=1}^{n}P_i(x).

This is proposed as an analogue of the Hawaiian conjecture for the class QPn\mathcal{QP}_n, based on numerical experiments. The source does not state whether either assertion has been proved or disproved.

References

Primary source

Julius Borcea and Boris Shapiro, “Classifying real polynomial pencils”, arXiv:math/0404215 (2004).

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