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We initiate the study of a class of polytopes, which we coin polypositroids, defined to be those polytopes that are simultaneously generalized permutohedra (or polymatroids) and alcoved polytopes. Whereas positroids are the matroids arising…

Combinatorics · Mathematics 2020-10-15 Thomas Lam , Alexander Postnikov

Multi-degree splines are smooth piecewise-polynomial functions where the pieces can have different degrees. We describe a simple algorithmic construction of a set of basis functions for the space of multi-degree splines, with similar…

Numerical Analysis · Mathematics 2021-10-19 Hendrik Speleers

The h-vector of a matroid M is an important invariant related to the independence complex of M and can also be recovered from an evaluation of its Tutte polynomial. A well-known conjecture of Stanley posits that the h-vector of a matroid is…

Combinatorics · Mathematics 2025-09-16 Scott Corry , Anton Dochtermann , Solís McClain , David Perkinson , Lixing Yi

An index-guiding photonic crystal fiber (PCF) with an array of air holes surrounding the silica core region has special characteristics compared to conventional single-mode fibers (SMFs). Using the effective index method and the Gaussian…

Materials Science · Physics 2007-05-23 G. S. Kliros , J. Konstantinidis , C. Thraskias

We provide a combinatorial way of computing Speyer's $g$-polynomial on arbitrary Schubert matroids via the enumeration of certain Delannoy paths. We define a new statistic of a basis in a matroid, and express the $g$-polynomial of a…

Combinatorics · Mathematics 2024-01-15 Luis Ferroni

The M-polynomial provides a unifying framework for a wide class of degree-based topological indices. Despite its structural importance, general methods for computing the M-polynomial under graph constructions remain limited. In this paper,…

Combinatorics · Mathematics 2026-03-12 El-Mehdi Mehiri , Sandi Klavžar

Let $f=f(x_1,\dots,x_m)$ be a multilinear polynomial over a field $F$. An $F$-algebra $A$ is said to be $f$-zpd ($f$-zero product determined) if every $m$-linear functional $\varphi\colon A^{m}\rightarrow F$ which preserves zeros of $f$ is…

Rings and Algebras · Mathematics 2023-10-24 Ž. Bajuk , M. Brešar , P. Fagundes , A. Ioppolo

Denham, Suciu and Panov, Ray computed ranks of homotopy groups and Poincar\'e series of a moment-angle-complex $\mathcal Z(\mathcal K$) / Davis-Januzskiewicz space $DJ(\mathcal K)$ associated to a flag simplicial complex $\mathcal K$. In…

Combinatorics · Mathematics 2016-10-14 Yury Ustinovskiy

Given a subgroup $\mathcal{H}$ of a product of finite groups $\mathcal{G} = \displaystyle\prod^n_{i=1} \Gamma_i$ and $b>1,$ we define a polymatroid $P(\mathcal{H},b).$ If all of the $\Gamma_i$ are isomorphic to $\mathbb{Z}/p\mathbb{Z},$ $p$…

Combinatorics · Mathematics 2024-02-28 Ed Swartz , Prairie Wentworth-Nice , Alexander Xue

Let $f(x,y)$ be a real polynomial of degree $d$ with isolated critical points, and let $i$ be the index of $grad f$ around a large circle containing the critical points. An elementary argument shows that $|i| \leq d-1$. In this paper we…

alg-geom · Mathematics 2008-02-03 Alan H. Durfee

We study the structure of the digit sets ${\mathcal D}$ for the integral self-similar tiles $T(b,{\mathcal{D}})$ (we call such ${\mathcal D}$ a {\it tile digit set} with respect to $b$). So far the only available classes of such tile digit…

Combinatorics · Mathematics 2013-05-02 Chun-Kit Lai , Ka-Sing Lau , Hui Rao

Let $k$ be a positive integer and let $G$ be a graph with $n$ vertices. A connected $k$-subpartition of $G$ is a collection of $k$ pairwise disjoint sets (a.k.a. classes) of vertices in $G$ such that each set induces a connected subgraph.…

Combinatorics · Mathematics 2025-12-23 Phablo F. S. Moura , Hande Yaman , Roel Leus

The nonnegative and positive semidefinite (PSD-) ranks are closely connected to the nonnegative and positive semidefinite extension complexities of a polytope, which are the minimal dimensions of linear and SDP programs which represent this…

Computational Complexity · Computer Science 2017-04-24 Andrii Riazanov , Mikhail Vyalyiy

We study paving matroids, their realization spaces, and their closures, along with matroid varieties and circuit varieties. Within this context, we introduce three distinct methods for generating polynomials within the associated ideals of…

Algebraic Geometry · Mathematics 2026-03-24 Emiliano Liwski , Fatemeh Mohammadi

We give algorithms for computing the singular moduli of suitable nonholomorphic modular functions F(z). By combining the theory of isogeny volcanoes with a beautiful observation of Masser concerning the nonholomorphic Eisenstein series…

Number Theory · Mathematics 2017-04-25 Jan Hendrik Bruinier , Ken Ono , Andrew V. Sutherland

In this paper we present an explicit combinatorial description of a special class of facets of the secondary polytopes of hypersimplices. These facets correspond to polytopal subdivisions called multi-splits. We show a relation between the…

Combinatorics · Mathematics 2019-10-10 Benjamin Schröter

We study an operation in matroid theory that allows one to transition a given matroid into another with more bases via relaxing a \emph{stressed subset}. This framework provides a new combinatorial characterization of the class of split…

Combinatorics · Mathematics 2024-09-12 Luis Ferroni , Benjamin Schröter

In 1977, Yu. V. Matiyasevich proposed a formula expressing the chromatic polynomial of an arbitrary graph as a linear combination of flow polynomials of subgraphs of the original graph. In this paper, we prove that this representation is a…

Combinatorics · Mathematics 2024-06-17 E. Yu. Lerner

In this paper we develop the theory of cyclic flats of $q$-matroids. We show that the lattice of cyclic flats, together with their ranks, uniquely determines a $q$-matroid and hence derive a new $q$-cryptomorphism. We introduce the notion…

Combinatorics · Mathematics 2023-02-15 Gianira N. Alfarano , Eimear Byrne

Flag matroids are a rich family of Coxeter matroids that can be characterized using pairs of matroids that form a quotient. We consider a class of matroids called positroids, introduced by Postnikov, and utilize their combinatorial…

Combinatorics · Mathematics 2019-12-17 Carolina Benedetti , Anastasia Chavez , Daniel Tamayo