Explicit Construction of Polytopes whose Ehrhart Polynomials Realize any Given Sign Pattern

Fuente: arXiv
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Main Authors: Liu, Feihu, Tao, Sihao, Xin, Guoce
Format: Preprint
Published: 2026
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author Liu, Feihu
Tao, Sihao
Xin, Guoce
author_facet Liu, Feihu
Tao, Sihao
Xin, Guoce
contents In Ehrhart theory, the well-known sign pattern problem asks: given a positive integer $d\geq 3$ and integers $1 \leq i_1 < \cdots < i_k \leq d-2$, does there exist a $d$-dimensional integral polytope $\mathcal{P}$ such that in its Ehrhart polynomial $i(\mathcal{P}, t)$ the coefficients of $t^{i_1}, \ldots, t^{i_k}$ are negative, while all remaining coefficients are positive? This problem was proposed by Hibi, Higashitani, Tsuchiya, and Yoshida. In this paper, we first construct a class of simplices $\mathcal{S}_d(m)$ whose Ehrhart polynomial has leading coefficient $m$ and all other coefficients fixed positive constants. Then, using the Cartesian product of $\mathcal{S}_d(m)$ and the Reeve tetrahedron, we obtain the first complete solution to the sign pattern problem. Finally, while attacking the sign pattern problem, we discovered a fast algorithm for computing the $h^*$-polynomial of a class of simplices $Δ(0,q)$. This algorithm is crucial for constructing the simplices $\mathcal{S}_d(m)$.
format Preprint
id arxiv_https___arxiv_org_abs_2605_23544
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Explicit Construction of Polytopes whose Ehrhart Polynomials Realize any Given Sign Pattern
Liu, Feihu
Tao, Sihao
Xin, Guoce
Combinatorics
In Ehrhart theory, the well-known sign pattern problem asks: given a positive integer $d\geq 3$ and integers $1 \leq i_1 < \cdots < i_k \leq d-2$, does there exist a $d$-dimensional integral polytope $\mathcal{P}$ such that in its Ehrhart polynomial $i(\mathcal{P}, t)$ the coefficients of $t^{i_1}, \ldots, t^{i_k}$ are negative, while all remaining coefficients are positive? This problem was proposed by Hibi, Higashitani, Tsuchiya, and Yoshida. In this paper, we first construct a class of simplices $\mathcal{S}_d(m)$ whose Ehrhart polynomial has leading coefficient $m$ and all other coefficients fixed positive constants. Then, using the Cartesian product of $\mathcal{S}_d(m)$ and the Reeve tetrahedron, we obtain the first complete solution to the sign pattern problem. Finally, while attacking the sign pattern problem, we discovered a fast algorithm for computing the $h^*$-polynomial of a class of simplices $Δ(0,q)$. This algorithm is crucial for constructing the simplices $\mathcal{S}_d(m)$.
title Explicit Construction of Polytopes whose Ehrhart Polynomials Realize any Given Sign Pattern
topic Combinatorics
url https://arxiv.org/abs/2605.23544