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Ehrhart theory measures a polytope P discretely by counting the lattice points inside its dilates P, 2P, 3P, .... We compute the Ehrhart quasipolynomials of the standard Coxeter permutahedra for the classical Coxeter groups, expressing them…

Combinatorics · Mathematics 2021-12-21 Federico Ardila , Matthias Beck , Jodi McWhirter

We study the number of lattice points in integer dilates of the rational polytope $P = (x_1,...,x_n) \in \R_{\geq 0}^n : \sum_{k=1}^n x_k a_k \leq 1$, where $a_1,...,a_n$ are positive integers. This polytope is closely related to the linear…

Number Theory · Mathematics 2007-05-23 Matthias Beck , Ricardo Diaz , Sinai Robins

Let X be the set of integer points in some polyhedron. We investigate the smallest number of facets of any polyhedron whose set of integer points is X. This quantity, which we call the relaxation complexity of X, corresponds to the smallest…

Combinatorics · Mathematics 2014-12-12 Volker Kaibel , Stefan Weltge

The Ehrhart polynomial of a convex lattice polytope counts integer points in integral dilates of the polytope. We present new linear inequalities satisfied by the coefficients of Ehrhart polynomials and relate them to known inequalities. We…

Combinatorics · Mathematics 2007-05-23 M. Beck , J. A. De Loera , M. Develin , J. Pfeifle , R. P. Stanley

Let $ES_{d}(n)$ be the smallest integer such that any set of $ES_{d}(n)$ points in $\mathbb{R}^{d}$ in general position contains $n$ points in convex position. In 1960, Erd\H{o}s and Szekeres showed that $ES_{2}(n) \geq 2^{n-2} + 1$ holds,…

Combinatorics · Mathematics 2022-08-10 Cosmin Pohoata , Dmitrii Zakharov

Let a polytope $P$ be defined by a system $A x \leq b$. We consider the problem of counting the number of integer points inside $P$, assuming that $P$ is $\Delta$-modular, where the polytope $P$ is called $\Delta$-modular if all the rank…

Computational Complexity · Computer Science 2023-05-09 D. V. Gribanov , D. S. Malyshev

We show that the polytopes obtained from the Birkhoff polytope by imposing additional inequalities restricting the "longest increasing subsequence" have Ehrhart quasi-polynomials which are honest polynomials, even though they are just…

Combinatorics · Mathematics 2023-12-21 Per Alexandersson , Sam Hopkins , Gjergji Zaimi

We give novel and explicit formulas for the Ehrhart quasi-polynomials of rational simple polytopes, in terms of Barnes polynomials and discrete moments of half-open parallelepipeds. These formulas also hold for all positive dilations of a…

Combinatorics · Mathematics 2026-02-02 Sinai Robins

We investigate the complexity of counting the number of integer points in tropical polytopes, and the complexity of calculating their volume. We study the tropical analogue of the outer parallel body and establish bounds for its volume. We…

Computational Complexity · Computer Science 2019-12-30 Stephane Gaubert , Marie MacCaig

We give a new proof for a theorem of Ehrhart regarding the quasi-polynomiality of the function that counts the number of integer points in the integral dilates of a rational polytope. The proof involves a geometric bijection,…

Combinatorics · Mathematics 2012-12-27 Steven V Sam

If $P$ is a lattice polytope (i.e., $P$ is the convex hull of finitely many integer points in $\mathbb{R}^d$) of dimension $d$, Ehrhart's famous theorem (1962) asserts that the integer-point counting function $|nP \cap \mathbb{Z}^d|$ is a…

Combinatorics · Mathematics 2024-09-24 Esme Bajo , Matthias Beck

We prove that computing a shortest monotone path to the optimum of a linear program over a simple polytope is NP-hard, thus resolving a 2022 open question of De Loera, Kafer, and Sanit\`a. As a consequence, finding a shortest sequence of…

Data Structures and Algorithms · Computer Science 2026-04-09 Alexander E. Black , Raphael Steiner

In this paper, we consider the counting function $E_P(y) = |P_{y} \cap Z^{n_x}|$ for a parametric polyhedron $P_{y} = \{x \in R^{n_x} \colon A x \leq b + B y\}$, where $y \in R^{n_y}$. We give a new representation of $E_P(y)$, called a…

Data Structures and Algorithms · Computer Science 2024-12-05 D. Gribanov , D. Malyshev , P. Pardalos , N. Zolotykh

We consider the discrepancy of the integer lattice with respect to the collection of all translated copies of a dilated convex body having a finite number of flat, possibly non-smooth, points in its boundary. We estimate the $L^{p}$ norm of…

Functional Analysis · Mathematics 2018-10-02 Luca Brandolini , Leonardo Colzani , Bianca Gariboldi , Giacomo Gigante , Giancarlo Travaglini

We describe a maximum entropy approach for computing volumes and counting integer points in polyhedra. To estimate the number of points from a particular set X in R^n in a polyhedron P in R^n, by solving a certain entropy maximization…

Combinatorics · Mathematics 2009-07-15 Alexander Barvinok , John Hartigan

We classify, according to their computational complexity, integer optimization problems whose constraints and objective functions are polynomials with integer coefficients and the number of variables is fixed. For the optimization of an…

Optimization and Control · Mathematics 2017-01-03 Jesús A. De Loera , Raymond Hemmecke , Matthias Köppe , Robert Weismantel

In this paper we investigate the Ehrhart Theory of the independence matroid polytope of uniform matroids. It is proved that these polytopes have an Ehrhart polynomial with positive coefficients. To do that, we prove that indeed all…

Combinatorics · Mathematics 2021-05-24 Luis Ferroni

We present an algorithm for growing the denominator $r$ polygons containing a fixed number of lattice points and enumerate such polygons containing few lattice points for small $r$. We describe the Ehrhart quasi-polynomial of a rational…

Combinatorics · Mathematics 2024-12-02 Girtrude Hamm , Johannes Hofscheier , Alexander Kasprzyk

The Ehrhart quasipolynomial of a rational polytope $\mathsf{P}$ encodes fundamental arithmetic data of $\mathsf{P}$, namely, the number of integer lattice points in positive integral dilates of $\mathsf{P}$. Ehrhart quasipolynomials were…

Combinatorics · Mathematics 2023-08-29 Matthias Beck , Sophia Elia , Sophie Rehberg

The Ehrhart polynomial of an integral convex polytope counts the number of lattice points in dilates of the polytope. In math.CO/0402148, the authors conjectured that for any cyclic polytope with integral parameters, the Ehrhart polynomial…

Combinatorics · Mathematics 2007-05-23 Fu Liu