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We study orbit closures and stationary measures for groups of automorphisms of $p$-adic affine surfaces.

Algebraic Geometry · Mathematics 2024-10-14 Serge Cantat , Seung Uk Jang

Let $\Phi$ be an irreducible crystallographic root system and $\mathcal P$ its root polytope, i.e., its convex hull. We provide a uniform construction, for all root types, of a triangulation of the facets of $\mathcal P$. We also prove…

Combinatorics · Mathematics 2016-12-20 Paola Cellini

The convex hulls of face-vertex incident vectors of 3-face-colorable convex polytopes are computed. It is found that every such convex hull is a $d$-polytope with $d+2$ or $d+3$ vertices. Utilizing Gale transform and Gale diagram, we…

Combinatorics · Mathematics 2021-11-01 Bo Chen , Chen Peng , Yueshan Xiong

The secondary polytope of a point configuration A is a polytope whose face poset is isomorphic to the poset of all regular subdivisions of A. While the vertices of the secondary polytope - corresponding to the triangulations of A - are very…

Combinatorics · Mathematics 2014-12-23 Sven Herrmann

The polar ring galaxies (PRGs) represent an interesting type of peculiar systems in which the outer matter is rotating in the plane which is roughly perpendicular to the disk of the main galaxy. Despite the long lasting study of the PRGs…

Astrophysics of Galaxies · Physics 2018-03-14 A. Moiseev , S. Khoperskov , A. Khoperskov , K. Smirnova , A. Smirnova , A. Saburova , V. Reshetnikov

A cosmological polytope is a lattice polytope introduced by Arkani-Hamed, Benincasa, and Postnikov in their study of the wavefunction of the universe in a class of cosmological models. More concretely, they construct a cosmological polytope…

Combinatorics · Mathematics 2025-05-21 Lukas Kühne , Leonid Monin

We study a class of semialgebraic convex bodies called discotopes. These are instances of zonoids, objects of interest in real algebraic geometry and random geometry. We focus on the face structure and on the boundary hypersurface of…

Algebraic Geometry · Mathematics 2025-06-02 Fulvio Gesmundo , Chiara Meroni

The restricted planar elliptic three body problem (RPETBP) describes the motion of a massless particle (a comet) under the gravitational field of two massive bodies (the primaries, say the Sun and Jupiter) revolving around their center of…

Dynamical Systems · Mathematics 2018-08-07 Amadeu Delshams , Vadim Kaloshin , Abraham de la Rosa , Tere M. Seara

A centrally symmetric analogue of the cyclic polytope, the bicyclic polytope, was defined in [BN08]. The bicyclic polytope is defined by the convex hull of finitely many points on the symmetric moment curve where the set of points has a…

Combinatorics · Mathematics 2011-02-28 Seung Jin Lee

We examine the orbits of the (complex) symplectic group, $Sp_n$, on the flag manifold, $\mathscr{F}\ell(\mathbb{C}^{2n})$, in a very concrete way. We use two approaches: we Gr\"obner degenerate the orbits to unions of Schubert varieties…

Algebraic Geometry · Mathematics 2014-11-11 Anna Bertiger

Let $\Phi$ be a finite crystallographic irreducible root system and $\mathcal P_{\Phi}$ be the convex hull of the roots in $\Phi$. We give a uniform explicit description of the polytope $\mathcal P_{\Phi}$, analyze the…

Combinatorics · Mathematics 2016-11-07 Paola Cellini , Mario Marietti

We study metric properties of convex bodies B and their polars B^o, where B is the convex hull of an orbit under the action of a compact group G. Examples include the Traveling Salesman Polytope in polyhedral combinatorics (G=S_n, the…

Metric Geometry · Mathematics 2007-05-23 Alexander Barvinok , Grigoriy Blekherman

We determine the extreme points and facets of the convex hull of all dual degree partitions of simple graphs on $n$ vertices.

Combinatorics · Mathematics 2007-05-23 Amitava Bhattacharya , Shmuel Friedland , Uri N. Peled

Off-equatorial circular orbits with constant latitudes (halo orbits) of electrically charged particles exist near compact objects. In the previous paper, we discussed this kind of motion and demonstrated the existence of minima of the…

High Energy Astrophysical Phenomena · Physics 2010-05-19 Jiri Kovar , Ondrej Kopacek , Vladimir Karas , Zdenek Stuchlik

Hyperbolic polynomials elegantly encode a rich class of convex cones that includes polyhedral and spectrahedral cones. Hyperbolic polynomials are closed under taking polars and the corresponding cones, the derivative cones, yield…

Optimization and Control · Mathematics 2011-11-11 Raman Sanyal

By decomposing the regular representation of a particular (Heisenberg-like) Lie supergroup into irreducible subspaces, we show that not all of them can be obtained by applying geometric quantization to coadjoint orbits with an even…

Mathematical Physics · Physics 2010-10-04 Gijs M. Tuynman

Rotation distorts the vacuum magnetic field of a pulsar from that of a simple dipole. The effect is particularly strong close to the light cylinder, but also affects the field close to the stellar surface. We find the shape and locus of the…

Astrophysics · Physics 2012-08-27 P. N. Arendt, , J. A. Eilek

Abstract polytopes generalize the classical notion of convex polytopes to more general combinatorial structures. The most studied ones are regular and chiral polytopes, as it is well-known, they can be constructed as coset geometries from…

Combinatorics · Mathematics 2023-04-06 Isabel Hubard , Elías Mochán

For a projective hypersurface $X \subset \P^n$, the images of the polar maps of degree $k$ are studied. The cohomology class defined by these maps is calculated and classical results on dual varieties are presented as applications.

Algebraic Geometry · Mathematics 2008-11-06 Luis E. Lopez

This article studies a large, general class of orthogonal polytopes which we may call "generic orthotopes". These objects emerged from a desire to represent a Coxeter complex by an orthogonal polytope that is particularly nice with respect…

Combinatorics · Mathematics 2022-10-24 David Richter