Abstract
We give a description of the tropical Severi variety of univariate polynomials of degree n having two double roots. We show that, as a set, it is given as the union of three explicit types of cones of maximal dimension n − 1, where only cones of two of these types are cones of the secondary fan of {0,..., n}. Through Kapranov’s theorem, this goal is achieved by a careful study of the possible valuations of the elementary symmetric functions of the roots of a polynomial with two double roots. Despite its apparent simplicity, the computation of the tropical Severi variety has both combinatorial and arithmetic ingredients.
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Dickenstein, A., Herrero, M.I. & Tabera, L.F. Arithmetics and combinatorics of tropical Severi varieties of univariate polynomials. Isr. J. Math. 221, 741–777 (2017). https://doi.org/10.1007/s11856-017-1573-0
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DOI: https://doi.org/10.1007/s11856-017-1573-0