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An associahedron is a polytope whose vertices correspond to triangulations of a convex polygon and whose edges correspond to flips between them. Using labeled polygons, C. Hohlweg and C. Lange constructed various realizations of the…

Combinatorics · Mathematics 2023-11-14 Carsten Lange , Vincent Pilaud

A natural way of generalising Hamiltonian toric manifolds is to permit the presence of generic isolated singularities for the moment map. For a class of such ``almost-toric 4-manifolds'' which admits a Hamiltonian $S^1$-action we show that…

Symplectic Geometry · Mathematics 2007-05-23 San Vu Ngoc

We present a combinatorial isomorphism between Stasheff associahedra and an inductive cone construction of those complexes given by Loday. We give an alternate description of certain polytopes, known as multiplihedra, which arise in the…

Combinatorics · Mathematics 2025-11-25 Somnath Basu , Sandip Samanta

We prove the combinatorial property of shortness for freehedra. Note that associahedra, a sibling family of polytopes, are not short.

Combinatorics · Mathematics 2022-01-03 Daria Poliakova

We review three realizations of the associahedron that arise as secondary polytopes, from cluster algebras, and as Minkowski sums of simplices, and show that under any choice of parameters, the resulting associahedra are affinely…

Metric Geometry · Mathematics 2011-09-29 Cesar Ceballos , Günter M. Ziegler

To any graph $G$ one can associate a toric variety $X(\mathcal{P}G)$, obtained as a blowup of projective space along coordinate subspaces corresponding to connected subgraphs of $G$. The polytope of this toric variety is the graph…

Algebraic Geometry · Mathematics 2017-06-06 Rodrigo Ferreira da Rosa , David Jensen , Dhruv Ranganathan

The volume and the number of lattice points of the permutohedron P_n are given by certain multivariate polynomials that have remarkable combinatorial properties. We give several different formulas for these polynomials. We also study a more…

Combinatorics · Mathematics 2007-05-23 Alexander Postnikov

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

Scattering amplitudes of $\operatorname{tr}(\phi^3)$ theory can be encoded as the canonical form of the Stasheff associahedron. Similarly, the flat-space wavefunction coefficients of the same theory are captured by the recently proposed…

High Energy Physics - Theory · Physics 2025-11-17 Stefan Forcey , Ross Glew , Hyungrok Kim

We give an explicit subword complex description of the generators of the type cone of the g-vector fan of a finite type cluster algebra with acyclic initial seed. This yields in particular a description of the Newton polytopes of the…

Combinatorics · Mathematics 2020-06-19 Dennis Jahn , Robert Löwe , Christian Stump

Generalized permutahedra are the polytopes obtained from the permutahedron by changing the edge lengths while preserving the edge directions, possibly identifying vertices along the way. We introduce a "lifting" construction for these…

Combinatorics · Mathematics 2013-02-25 Federico Ardila , Jeffrey Doker

We investigate a family of polytopes introduced by E.M.\ Feichtner, A.\ Postnikov and B.\ Sturmfels, which were named nestohedra. The vertices of these polytopes may intuitively be understood as constructions of hypergraphs. Limit cases in…

Combinatorics · Mathematics 2011-10-07 K. Dosen , Z. Petric

In this short note we consider generalized associahedra of type D_n. We prove that these simple flag polytopes are not nestohedra for n > 3, but the statement of Gal's conjecture holds for them.

Combinatorics · Mathematics 2011-06-10 Mikhail Gorsky

Given a graph G, we construct a simple, convex polytope whose face poset is based on the connected subgraphs of G. This provides a natural generalization of the Stasheff associahedron and the Bott-Taubes cyclohedron. Moreover, we show that…

Quantum Algebra · Mathematics 2007-05-23 Michael Carr , Satyan L. Devadoss

Alcoved polytopes are characterized by the property that all facet normal directions are parallel to the roots $e_i-e_j$. Unlike other prominent families of polytopes, like generalized permutahedra, alcoved polytopes are not closed under…

Combinatorics · Mathematics 2025-11-05 Nick Early , Lukas Kühne , Leonid Monin

We define a family of convex polytopes called constrainahedra, which index collisions of horizontal and vertical lines. Our construction proceeds by first defining a poset $C(m,n)$ of good rectangular preorders, then proving that $C(m,n)$…

Combinatorics · Mathematics 2022-09-01 Nathaniel Bottman , Daria Poliakova

A graph associahedron is a polytope dual to a simplicial complex whose elements are induced connected subgraphs called tubes. Graph associahedra generalize permutahedra, associahedra, and cyclohedra, and therefore are of great interest to…

Combinatorics · Mathematics 2022-11-07 Jordan Almeter

Using elementary graded automorphisms of polytopal algebras (essentially the coordinate rings of projective toric varieties) polyhedral versions of the group of elementary matrices and the Steinberg and Milnor groups are defined. They…

K-Theory and Homology · Mathematics 2007-05-23 Winfried Bruns , Joseph Gubeladze

In this paper, we use subword complexes to provide a uniform approach to finite type cluster complexes and multi-associahedra. We introduce, for any finite Coxeter group and any nonnegative integer k, a spherical subword complex called…

Combinatorics · Mathematics 2013-07-11 Cesar Ceballos , Jean-Philippe Labbé , Christian Stump

It is proved that the generalized cluster complex defined by Fomin and Reading has a dihedral symmetry. Together with diagram symmetries, they generate its automorphism group. A consequence is a simple explicit formula for the order of this…

Combinatorics · Mathematics 2025-04-09 Matthieu Josuat-Vergès