Real-rooted Ehrhart $h^*$-polynomials of crown posets and wheel and whirl matroids

Ying Cao; Houshan Fu

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arXiv · 2610.40496

Real-rooted Ehrhart $h^*$-polynomials of crown posets and wheel and whirl matroids

Ying Cao·Houshan Fu

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Abstract

We prove that the Ehrhart $h^*$-polynomials of crown order polytopes are real-rooted, settling a conjecture of Lundström and Saud Maia Leite. For each integer $r\ge3$, the crown order polytope on $2r$ elements and the rank-$r$ whirl base polytope have the same $h^*$-polynomial. The $h^*$-polynomials of the rank-$r$ wheel and whirl base polytopes, as well as every convex combination of the two, have $2r-2$ distinct negative roots. Their coefficient sequences are positive, unimodal, and strictly ultra log-concave of order $2r-2$.

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Ying Cao, Houshan Fu. 2026-10-29. Real-rooted Ehrhart $h^*$-polynomials of crown posets and wheel and whirl matroids. https://arxiv.org/abs/2610.40496

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