Weighted Ehrhart Theory: Extending Stanley's nonnegativity theorem
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arXiv
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| Main Authors: | , , , , , , |
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| Format: | Preprint |
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2023
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| _version_ | 1866910690254520320 |
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| author | Bajo, Esme Davis, Robert De Loera, Jesús A. Garber, Alexey Mora, Sofía Garzón Jochemko, Katharina Yu, Josephine |
| author_facet | Bajo, Esme Davis, Robert De Loera, Jesús A. Garber, Alexey Mora, Sofía Garzón Jochemko, Katharina Yu, Josephine |
| contents | We generalize R. P. Stanley's celebrated theorem that the $h^\ast$-polynomial of the Ehrhart series of a rational polytope has nonnegative coefficients and is monotone under containment of polytopes. We show that these results continue to hold for weighted Ehrhart series where lattice points are counted with polynomial weights, as long as the weights are homogeneous polynomials decomposable as sums of products of linear forms that are nonnegative on the polytope. We also show nonnegativity of the $h^\ast$-polynomial as a real-valued function for a larger family of weights.
We then target the case when the weight function is the square of a single (arbitrary) linear form. We show stronger results for two-dimensional convex lattice polygons and give concrete examples showing tightness of the hypotheses. As an application, we construct a counterexample to a conjecture by Berg, Jochemko, and Silverstein on Ehrhart tensor polynomials. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2303_09614 |
| institution | arXiv |
| publishDate | 2023 |
| record_format | arxiv |
| spellingShingle | Weighted Ehrhart Theory: Extending Stanley's nonnegativity theorem Bajo, Esme Davis, Robert De Loera, Jesús A. Garber, Alexey Mora, Sofía Garzón Jochemko, Katharina Yu, Josephine Combinatorics Metric Geometry 52B20, 05A15, 52B45 We generalize R. P. Stanley's celebrated theorem that the $h^\ast$-polynomial of the Ehrhart series of a rational polytope has nonnegative coefficients and is monotone under containment of polytopes. We show that these results continue to hold for weighted Ehrhart series where lattice points are counted with polynomial weights, as long as the weights are homogeneous polynomials decomposable as sums of products of linear forms that are nonnegative on the polytope. We also show nonnegativity of the $h^\ast$-polynomial as a real-valued function for a larger family of weights. We then target the case when the weight function is the square of a single (arbitrary) linear form. We show stronger results for two-dimensional convex lattice polygons and give concrete examples showing tightness of the hypotheses. As an application, we construct a counterexample to a conjecture by Berg, Jochemko, and Silverstein on Ehrhart tensor polynomials. |
| title | Weighted Ehrhart Theory: Extending Stanley's nonnegativity theorem |
| topic | Combinatorics Metric Geometry 52B20, 05A15, 52B45 |
| url | https://arxiv.org/abs/2303.09614 |