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Given a finite Coxeter system $(W,S)$ and a Coxeter element $c$, we construct a simple polytope whose outer normal fan is N. Reading's Cambrian fan $F_c$, settling a conjecture of Reading that this is possible. We call this polytope the…

Combinatorics · Mathematics 2011-12-20 Christophe Hohlweg , Carsten Lange , Hugh Thomas

For an abelian length category $\mathcal{A}$ with only finitely many isoclasses of simple objects, we have the wall-chamber structure and the TF equivalence on the dual real Grothendieck group…

Representation Theory · Mathematics 2026-03-09 Sota Asai , Osamu Iyama

This article studies the relationship between tropical Severi varieties and secondary fans. In the case when tropical Severi varieties are hypersurfaces this relationship is very well known; specifically, in this case, a tropical Severi…

Algebraic Geometry · Mathematics 2015-12-08 Jihyeon Jessie Yang

We define the unipotent tropical fundamental group of a polyhedral complex in $\mathbb{R}^n$ as the Tannakian fundamental group of the category of unipotent tropical vector bundles with integrable connection. We show that it is computable…

Algebraic Geometry · Mathematics 2024-06-21 Kyle Binder , Eric Katz

We prove that any affine, resp. polarized projective, spherical variety admits a flat degeneration to an affine, resp. polarized projective, toric variety. Motivated by Mirror Symmetry, we give conditions for the limit toric variety to be a…

Algebraic Geometry · Mathematics 2007-05-23 Valery Alexeev , Michel Brion

We introduce the notion of a tropical coamoeba which gives a combinatorial description of the Fukaya category of the mirror of a toric Fano stack. We show that the polyhedral decomposition of a real n-torus into (n + 1) permutohedra gives a…

Symplectic Geometry · Mathematics 2014-07-15 Masahiro Futaki , Kazushi Ueda

The Chow polytope of an algebraic cycle in a torus depends only on its tropicalisation. Generalising this, we associate a Chow polytope to any abstract tropical variety in a tropicalised toric variety. Several significant polyhedra…

Algebraic Geometry · Mathematics 2010-06-01 Alex Fink

Given a root system $\Phi$ of type $A_n$, $B_n$, $C_n$, or $D_n$ in Euclidean space $E$, let $W$ be the associated Weyl group. For a point $p \in E$ not orthogonal to any of the roots in $\Phi$, we consider the $W$-permutohedron $P_W$,…

Algebraic Geometry · Mathematics 2021-05-13 Tatsuya Horiguchi , Mikiya Masuda , John Shareshian , Jongbaek Song

Real toric manifolds are the real loci of nonsingular complete toric varieties. In this paper, we calculate the integral cohomology groups of real toric manifolds in terms of the combinatorial data contained in the underlying simplicial…

Algebraic Topology · Mathematics 2025-12-19 Feifei Fan

A tropical expansion is a degeneration of a toroidal embedding, induced by a polyhedral subdivision of its tropicalisation. Each irreducible component of a tropical expansion admits a collapsing map down to a stratum of the original…

Algebraic Geometry · Mathematics 2025-11-21 Francesca Carocci , Navid Nabijou

Viewing a fan as a partially ordered set (of cones) we consider a category of sheaves on the fan which corresponds to a category of equivariant sheaves on the corresponding toric variety if the fan is rational. In this category we define an…

Algebraic Geometry · Mathematics 2007-05-23 Paul Bressler , Valery A. Lunts

We use Altmann's toric fan description of P-resolutions to formulate a new description of deformation theory invariants for two-dimensional cyclic quotient singularities. In particular, we show how to calculate the dimensions of the…

Algebraic Geometry · Mathematics 2019-11-26 Nathan Owen Ilten

Tropicalization is a procedure that assigns polyhedral complexes to algebraic subvarieties of a torus. If one fixes a weighted polyhedral complex, one may study the set of all subvarieties of a toric variety that have that complex as their…

Algebraic Geometry · Mathematics 2012-06-18 Eric Katz

We construct fans which give Kato-Usui partial compactifications of period domains of weight -1. Similarly to the fans of toroidal compactifications, these fans are given by polyhedral decompositions. We also show a fibration structure for…

Algebraic Geometry · Mathematics 2014-03-04 Tatsuki Hayama

Using the language of polyhedral divisors and divisorial fans we describe invariant divisors on normal varieties X which admit an effective codimension one torus action. In this picture X is given by a divisorial fan on a smooth projective…

Algebraic Geometry · Mathematics 2011-04-05 Lars Petersen , Hendrik Süß

We show that the algebraic invariants multiplicity and depth of a graded ideal in the polynomial ring are closely connected to the fan structure of its generic tropical variety in the constant coefficient case. Generically the multiplicity…

Commutative Algebra · Mathematics 2021-05-18 Tim Roemer , Kirsten Schmitz

We show that any normal toric variety over a rank one valuation ring admits an equivariant open embedding in a normal toric variety which is proper over the valuation ring, after a base-change by a finite extension of valuation rings. If…

Algebraic Geometry · Mathematics 2019-08-02 Netanel Friedenberg

We present an explicit expression for the normalized height of a projective toric variety. This expression decomposes as a sum of local contributions, each term being the integral of a certain function, concave and piecewise linear-affine.…

Number Theory · Mathematics 2007-05-23 Patrice Philippon , Martin Sombra

In this article, we investigate the toric Schubert varieties in partial flag varieties $G/P$ for a connected semisimple algebraic group $G$. Using Deodhar's decomposition of Richardson varieties and the work of Pasquier, we give an explicit…

Combinatorics · Mathematics 2026-05-05 Mahir Bilen Can , Arpita Nayek , Pinakinath Saha

We extend tropicalization and tropical compactification of subvarieties of algebraic tori to subvarieties of spherical homogeneous spaces. Given a tropical compactification of a subvariety, we show that the support of the colored fan of the…

Algebraic Geometry · Mathematics 2020-08-31 Jenia Tevelev , Tassos Vogiannou