Abstract
We study the root distribution of some univariate polynomials satisfying a recurrence of order two with linear polynomial coefficients. We show that the set of non-isolated limits of zeros of the polynomials is either an arc, or a circle, or an interval, or a “lollipop.” As an application, we discover a sufficient and necessary condition for the universal real-rootedness of the polynomials, subject to certain sign condition on the coefficients of the recurrence. Moreover, we obtain the sharp bound for all the zeros when they are real.
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Communicated by Fuad Kittaneh.
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D.G.L. Wang is supported by the General Program of National Natural Science Foundation of China (Grant No. 11671037). This paper is completed when the first author is a visiting scholar at MIT.
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Wang, D.G.L., Zhang, J.J.R. Geometry of Limits of Zeros of Polynomial Sequences of Type (1,1). Bull. Malays. Math. Sci. Soc. 44, 785–803 (2021). https://doi.org/10.1007/s40840-020-00975-y
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DOI: https://doi.org/10.1007/s40840-020-00975-y