Borcea's normal-matrix spectral-distance conjecture

From papers

Let AA be an n×nn\times n normal matrix. Write W(A)W(A) for its numerical range, Σ(A)\Sigma(A) for its spectrum, and let AkA_k be the (n1)×(n1)(n-1)\times(n-1) matrix obtained by deleting the kkth row and column of AA. For compact sets, let HH denote the symmetrized Hausdorff distance.

Borcea's normal-matrix spectral-distance conjecture.

H(W(A),k=1nΣ(Ak))mincCAcI.H\left(W(A),\bigcup_{k=1}^n\Sigma(A_k)\right)\leq\min_{c\in\mathbb C}\|A-cI\|.

This is presented as a matrix-theoretic generalization of Schmeisser's conjecture. The source provides no resolution.

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Sources & referencesView supporting material

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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