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We survey several old and new problems related to the number of simplicial spheres, the number of neighborly simplicial spheres, the number of centrally symmetric simplicial spheres that are cs-neighborly, and the transversal numbers of…

组合数学 · 数学 2022-08-04 Isabella Novik , Hailun Zheng

In this paper, we provide the upper bound and the lower bound of the sum of the number of spherical face-partition pair of simple spherical polytope $P$ with $p$ facets.

度量几何 · 数学 2024-12-06 Huhe Han

The aim of this paper is to give a survey of the known results concerning centrally symmetric polytopes, spheres, and manifolds. We further enumerate nearly neighborly centrally symmetric spheres and centrally symmetric products of spheres…

度量几何 · 数学 2007-05-23 Frank H. Lutz

We study $n$-vertex $d$-dimensional polytopes with at most one nonsimplex facet with, say, $d+s$ vertices, called {\it almost simplicial polytopes}. We provide tight lower and upper bound theorems for these polytopes as functions of $d,n$…

组合数学 · 数学 2018-11-20 Eran Nevo , Guillermo Pineda-Villavicencio , Julien Ugon , David Yost

We present explicit constructions of centrally symmetric polytopes with many faces: first, we construct a d-dimensional centrally symmetric polytope P with about (1.316)^d vertices such that every pair of non-antipodal vertices of P spans…

度量几何 · 数学 2011-11-21 Alexander Barvinok , Seung Jin Lee , Isabella Novik

Let $f_i(P)$ denote the number of $i$-dimensional faces of a convex polytope $P$. Furthermore, let $S(n,d)$ and $C(n,d)$ denote, respectively, the stacked and the cyclic $d$-dimensional polytopes on $n$ vertices. Our main result is that for…

组合数学 · 数学 2007-05-23 Anders Björner

We prove new upper and lower bounds on transversal numbers of several classes of simplicial complexes. Specifically, we establish an upper bound on the transversal numbers of pure simplicial complexes in terms of the number of vertices and…

组合数学 · 数学 2025-10-09 Isabella Novik , Hailun Zheng

Symmetric edge polytopes, a.k.a. PV-type adjacency polytopes, associated with undirected graphs have been defined and studied in several seemingly independent areas including number theory, discrete geometry, and dynamical systems. In…

组合数学 · 数学 2022-12-02 Tianran Chen , Robert Davis , Evgeniia Korchevskaia

We consider simplicial polytopes, and more general simplicial complexes, without missing faces above a fixed dimension. Sharp analogues of McMullen's generalized lower bounds, and of Barnette's lower bounds, are conjectured for these…

组合数学 · 数学 2009-04-24 Eran Nevo

In 1995, Jockusch constructed an infinite family of centrally symmetric $3$-dimensional simplicial spheres that are cs-$2$-neighborly. Here we generalize his construction and show that for all $d\geq 3$ and $n\geq d+1$, there exists a…

组合数学 · 数学 2020-04-24 Isabella Novik , Hailun Zheng

Symmetric edge polytopes are a recent and well-studied family of centrally symmetric polytopes arising from graphs. In this paper, we introduce a generalization of this family to arbitrary simplicial complexes. We show how topological…

组合数学 · 数学 2026-02-20 Torben Donzelmann , Thiago Holleben , Martina Juhnke

We show that there exist k-neighborly centrally symmetric d-dimensional polytopes with 2(n+d) vertices, where k(d,n)=Theta(d/(1+log ((d+n)/d))). We also show that this bound is tight.

组合数学 · 数学 2007-05-23 Nathan Linial , Isabella Novik

For a $(d-1)$-dimensional simplicial complex $\Delta$ and $1\leq i\leq d$, let $f_{i-1}$ be the number of $(i-1)$-faces of $\Delta$ and $m_i$ be the number of missing $i$-faces of $\Delta$. In the nineties, Kalai asked for a…

组合数学 · 数学 2025-09-24 Isabella Novik , Hailun Zheng

Stanley proved that for any centrally symmetric simplicial $d$-polytope $P$ with $d\geq 3$, $g_2(P) \geq {d \choose 2}-d$. We provide a characterization of centrally symmetric $d$-polytopes with $d\geq 4$ that satisfy this inequality as…

组合数学 · 数学 2018-11-13 Steven Klee , Eran Nevo , Isabella Novik , Hailun Zheng

A remarkable and important property of face numbers of simplicial polytopes is the generalized lower bound inequality, which says that the $h$-numbers of any simplicial polytope are unimodal. Recently, for balanced simplicial $d$-polytopes,…

组合数学 · 数学 2015-03-24 Martina Juhnke-Kubitzke , Satoshi Murai

We construct CW spheres from the lattices that arise as the closed sets of a convex closure, the meet-distributive lattices. These spheres are nearly polytopal, in the sense that their barycentric subdivisions are simplicial polytopes. The…

组合数学 · 数学 2007-05-23 Louis J. Billera , Samuel K. Hsiao , J. Scott Provan

We resolve a conjecture of Kalai relating approximation theory of convex bodies by simplicial polytopes to the face numbers and primitive Betti numbers of these polytopes and their toric varieties. The proof uses higher notions of…

度量几何 · 数学 2016-02-18 Karim Adiprasito , Eran Nevo , José Alejandro Samper

We define a centrally symmetric analogue of the cyclic polytope and study its facial structure. We conjecture that our polytopes provide asymptotically the largest number of faces in all dimensions among all centrally symmetric polytopes…

组合数学 · 数学 2007-05-23 Alexander Barvinok , Isabella Novik

The spherical centroid body of a centrally-symmetric convex body in the Euclidean unit sphere is introduced. Two alternative definitions - one geometric, the other probabilistic in nature - are given and shown to lead to the same objects.…

度量几何 · 数学 2019-02-28 Florian Besau , Thomas Hack , Peter Pivovarov , Franz E. Schuster

Orthogonal surfaces are nice mathematical objects which have interesting connections to various fields, e.g., integer programming, monomial ideals and order dimension. While orthogonal surfaces in one or two dimensions are rather trivial…

组合数学 · 数学 2007-05-23 Stefan Felsner , Sarah Kappes
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