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We define and study a new family of polytopes which are formed as convex hulls of partial alternating sign matrices. We determine the inequality descriptions, number of facets, and face lattices of these polytopes. We also study partial…

Combinatorics · Mathematics 2022-03-09 Dylan Heuer , Jessica Striker

A simple convex polytope $P$ is \emph{cohomologically rigid} if its combinatorial structure is determined by the cohomology ring of a quasitoric manifold over $P$. Not every $P$ has this property, but some important polytopes such as…

Algebraic Topology · Mathematics 2014-02-26 Suyoung Choi , Taras Panov , Dong Youp Suh

Multitriangulations, and more generally subword complexes, yield a large family of simplicial complexes that are homeomorphic to spheres. Until now, all attempts to prove or disprove that they can be realized as convex polytopes faced major…

Combinatorics · Mathematics 2021-05-07 Jean-Philippe Labbé

A family of polytopes introduced by E.M. Feichtner, A. Postnikov and B. Sturmfels, which were named nestohedra, consists in each dimension of an interval of polytopes starting with a simplex and ending with a permutohedron. This paper…

Combinatorics · Mathematics 2017-08-08 Zoran Petric

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

The cosmohedron was recently proposed as a polytope underlying the cosmological wavefunction for $\text{Tr}(\Phi^3)$ theory. Its faces were conjectured to be in bijection with Matryoshkas, which are obtained from a subdivision of a polygon…

Combinatorics · Mathematics 2026-03-23 Federico Ardila-Mantilla , Nima Arkani-Hamed , Carolina Figueiredo , Francisco Vazão

We introduce a new broadly unifying family of combinatorial objects, which we call permutation flows, associated to an acyclic directed graph $G$ together with a framing $F$. This new family is combinatorially rich and contains as special…

Combinatorics · Mathematics 2025-12-04 Rafael S. González D'León , Christopher R. H. Hanusa , Martha Yip

Many families of combinatorial objects have a Hopf monoid structure. Aguiar and Ardila introduced the Hopf monoid of generalized permutahedra and showed that it contains various other notable combinatorial families as Hopf submonoids,…

Combinatorics · Mathematics 2020-10-13 Mariel Supina

For an arbitrary finite Coxeter group W we define the family of Cambrian lattices for W as quotients of the weak order on W with respect to certain lattice congruences. We associate to each Cambrian lattice a complete fan, which we…

Combinatorics · Mathematics 2026-05-13 Nathan Reading

The associahedron is classically constructed as a removahedron, i.e. by deleting inequalities in the facet description of the permutahedron. This removahedral construction extends to all permutreehedra (which interpolate between the…

Combinatorics · Mathematics 2023-11-14 Doriann Albertin , Vincent Pilaud , Julian Ritter

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

This paper introduces an inductively defined tree notation for all the faces of polytopes arising from a simplex by truncations. This notation allows us to view inclusion of faces as the process of contracting tree edges. Our notation…

Combinatorics · Mathematics 2017-08-10 Pierre-Louis Curien , Jovana Obradovic , Jelena Ivanovic

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

Combinatorial Hopf algebras of trees exemplify the connections between operads and bialgebras. Painted trees were introduced recently as examples of how graded Hopf operads can bequeath Hopf structures upon compositions of coalgebras. We…

Combinatorics · Mathematics 2019-07-05 Lisa Berry , Stefan Forcey , Maria Ronco , Patrick Showers

We introduce permutrees, a unified model for permutations, binary trees, Cambrian trees and binary sequences. On the combinatorial side, we study the rotation lattices on permutrees and their lattice homomorphisms, unifying the weak order,…

Combinatorics · Mathematics 2023-11-14 Vincent Pilaud , Viviane Pons

Motivated by the theory of cluster algebras, F. Chapoton, S. Fomin and A. Zelevinsky associated to each finite type root system a simple convex polytope called \emph{generalized associahedron}. They provided an explicit realization of this…

Combinatorics · Mathematics 2012-10-24 Salvatore Stella

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

Realisations of associahedra with linearly non-isomorphic normal fans can be obtained by alteration of the right-hand sides of the facet-defining inequalities from a classical permutahedron. These polytopes can be expressed as Minkowski…

Metric Geometry · Mathematics 2015-06-26 Carsten Lange

We introduce the simple extension complexity of a polytope P as the smallest number of facets of any simple (i.e., non-degenerate in the sense of linear programming) polytope which can be projected onto P. We devise a combinatorial method…

Combinatorics · Mathematics 2015-01-23 Volker Kaibel , Matthias Walter

We describe the cone of deformations of a Coxeter permutahedron, or equivalently, the nef cone of the toric variety associated to a Coxeter complex. This family of polytopes contains polyhedral models for the Coxeter-theoretic analogs of…

Combinatorics · Mathematics 2020-03-03 Federico Ardila , Federico Castillo , Christopher Eur , Alexander Postnikov