Edrei–Saff–Varga modified width conjecture

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Let ff be an entire function of positive, finite order λ\lambda, and let pn(z)p_n(z) denote its nthn^\text{th} partial sum. Edrei–Saff–Varga's modified width conjecture. There exist an infinite sequence of positive integers NN and finitely many exceptional arguments θ1,θ2,…,θq\theta_1,\theta_2,\ldots,\theta_q such that the following hold: for every argument θ≠θj\theta\ne\theta_j, j=1,2,…,qj=1,2,\ldots,q, there is a positive sequence ρn\rho_n, n∈Nn\in N, with ρn→∞\rho_n\to\infty and ρn=O(n2/λ)\rho_n=O(n^{2/\lambda}), for which, for every fixed ϵ>0\epsilon>0, the number of zeros of pn(z)p_n(z) in

∣z−ρneiθ∣≤ρnn−1+ϵ\left|z-\rho_ne^{i\theta}\right|\leq\rho_nn^{-1+\epsilon}

tends to infinity as n→∞n\to\infty, n∈Nn\in N; and for every exceptional argument θj\theta_j, there is an integer m≥2m\geq2 and a positive sequence ρn\rho_n, n∈Nn\in N, with ρn→∞\rho_n\to\infty and ρn=O(n2/(λm))\rho_n=O(n^{2/(\lambda m)}), for which, for every fixed ϵ>0\epsilon>0, the number of zeros of pn(z)p_n(z) in

∣z−ρneiθj∣≤ρnn−1/m+ϵ\left|z-\rho_ne^{i\theta_j}\right|\leq\rho_nn^{-1/m+\epsilon}

tends to infinity as n→∞n\to\infty, n∈Nn\in N. The modified conjecture describes dense clustering of zeros in all but finitely many directions, with slower concentration allowed in exceptional directions associated with maximal exponential growth; its resolution is not specified in the source.

References

Primary source

Antonio R. Vargas, “Newman-Rivlin asymptotics for partial sums of power series”, arXiv:1503.04262 (2015).

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