Borcea's Toeplitz reformulation of the 2-variance conjecture

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Assume n≥3n\geq3, choose a1,…,an−1∈Ca_1,\dots,a_{n-1}\in\mathbb C, and set

a0=−∑k=1n−1ak.a_0=-\sum_{k=1}^{n-1}a_k.

Let BB be the (n−1)×(n−1)(n-1)\times(n-1) Toeplitz matrix

B=(a0a1…an−2an−1a0a1…vdots⋱⋱⋮a2…an−1a0).B=\begin{pmatrix}a_0&a_1&\dots&a_{n-2}\\a_{n-1}&a_0&a_1&\dots\\vdots&\ddots&\ddots&\vdots\\a_2&\dots&a_{n-1}&a_0\end{pmatrix}.

Borcea's Toeplitz conjecture. The matrix BB has at least one eigenvalue λ\lambda satisfying

∣λ∣2≤∑k=1n−1∣ak∣2.|\lambda|^2\leq\sum_{k=1}^{n-1}|a_k|^2.

The source states that this matrix conjecture is equivalent to Statement (i), and hence to the 2-variance conjecture. No resolution is given.

References

Primary source

Dmitry Khavinson, Rajesh Pereira, Mihai Putinar, Edward B. Saff and Serguei Shimorin, “Borcea's variance conjectures on the critical points of polynomials”, arXiv:1010.5167 (2011).

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