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We give a complete description of amoebas and coamoebas of $k$-dimensional very affine linear spaces in $(\mathbb{C}^*)^{n}$. This include an upper bound of their dimension, and we show that if a $k$-dimensional very affine linear space in…

Algebraic Geometry · Mathematics 2016-09-14 Mounir Nisse , Mikael Passare

The maximal dimension of commutative subspaces of $M_n(\mathbb{C})$ is known. So is the structure of such a subspace when the maximal dimension is achieved. We consider extensions of these results and ask the following natural questions: If…

Rings and Algebras · Mathematics 2023-08-07 Matjaž Omladič , Heydar Radjavi , Klemen Šivic

Answering a question by Nisse and Sottile, we derive a formula for the dimension of the amoeba of an irreducible algebraic variety.

Algebraic Geometry · Mathematics 2019-10-30 Jan Draisma , Johannes Rau , Chi Ho Yuen

An amoeba is the image of a subvariety of an algebraic torus under the logarithmic moment map. We consider some qualitative aspects of amoebas, establishing some results and posing problems for further study. These problems include…

Algebraic Geometry · Mathematics 2022-06-22 Mounir Nisse , Frank Sottile

In this short note we prove a lemma about the dimension of certain algebraic sets of matrices. This result is needed in our paper arXiv:1201.1672. The result presented here has also applications in other situations and so it should appear…

Algebraic Geometry · Mathematics 2012-01-12 Jairo Bochi , Nicolas Gourmelon

An $n$-dimensional algebraic variety in $({\mathbb C}^\times)^{2n}$ covers its amoeba as well as its coamoeba generically finite-to-one. We provide an upper bound for the volume of these amoebas as well as for the number of points in the…

Algebraic Geometry · Mathematics 2015-09-01 Grigory Mikhalkin

We show that the amoeba of a complex algebraic variety defined as the solutions to a generic system of $n$ polynomials in $n$ variables has a finite basis. In other words, it is the intersection of finitely many hypersurface amoebas.…

Algebraic Geometry · Mathematics 2014-04-15 Mounir Nisse

The amoeba of a Laurent polynomial $f \in \C[z_1^{\pm 1},\ldots,z_n^{\pm 1}]$ is the image of its zero set $\mathcal{V}(f)$ under the log-absolute-value map. Understanding the space of amoebas (i.e., the decomposition of the space of all…

Algebraic Geometry · Mathematics 2013-04-24 Thorsten Theobald , Timo de Wolff

The amoeba of an affine algebraic variety V in (C^*)^r is the image of V under the map (z_1, ..., z_r) -> (log|z_1|, ..., log|z_r|). We give a characterisation of the amoeba based on the triangle inequality, which we call testing for…

Algebraic Geometry · Mathematics 2007-05-23 Kevin Purbhoo

The computation of amoebas has been a challenging open problem for the last dozen years. The most natural approach, namely to compute an amoeba via its boundary, has not been practical so far since only a superset of the boundary, the…

Algebraic Geometry · Mathematics 2016-06-14 Franziska Schroeter , Timo de Wolff

Let K be a (commutative) field with characteristic not 2, and V be a linear subspace of n by n matrices that have at most two eigenvalues in K (respectively, at most one non-zero eigenvalue in K). We prove that the dimension of V is less…

Rings and Algebras · Mathematics 2014-03-18 Clément de Seguins Pazzis

In this paper, we study the amoeba volume of a given $k-$dimensional generic analytic variety $V$ of the complex algebraic torus $(\C^*)^n$. When $n\geq 2k$, we show that $V$ is algebraic if and only if the volume of its amoeba is finite.…

Algebraic Geometry · Mathematics 2011-08-09 Farid Madani , Mounir Nisse

For a finite partially ordered set we calculate the dimension of the variety of its subspace representations having fixed dimension vector. The dimension is given in terms of the Euler quadratic form associated with a partially ordered set,…

Representation Theory · Mathematics 2019-02-27 Claudia Cavalcante Fonseca , Kostiantyn Iusenko

In this paper we give a necessary and sufficient criterion for representability of a matroid over an algebraic closed field. This leads to an algorithm, based on an extension of Groebner Bases, in order to decide if a given matroid is…

Combinatorics · Mathematics 2007-05-23 Massimiliano Lunelli , Antonio Laface

We invent the notion of a {\it dimension of a variety} $V$ as the cardinality of all its proper {\it derived} subvarieties (of the same type). The dimensions of varieties of lattices, varieties of regular bands and other general algebraic…

Logic · Mathematics 2016-08-16 Ewa Graczyńska , Dietmar Schweigert

The paper deals with amoebas of $k$-dimensional algebraic varieties in the algebraic complex torus of dimension $n\geq 2k$. First, we show that the area of complex algebraic curve amoebas is finite. Moreover, we give an estimate of this…

Algebraic Geometry · Mathematics 2012-06-05 Farid Madani , Mounir Nisse

A celebrated result of Dol'nikov, and of \v{Z}ivaljevi\'c and Vre\'cica, asserts that for every collection of $m$ measures $\mu_1,\dots,\mu_m$ on the Euclidean space $\mathbb R^{n + m - 1}$ there exists a projection onto an $n$-dimensional…

Metric Geometry · Mathematics 2018-08-07 Pavle V. M. Blagojević , Roman Karasev , Alexander Magazinov

Given any complex Laurent polynomial $f$, $\mathrm{Amoeba}(f)$ is the image of its complex zero set under the coordinate-wise log absolute value map. We give an efficiently constructible polyhedral approximation, $\mathrm{ArchtTrop}(f)$, of…

Algebraic Geometry · Mathematics 2017-03-20 Martin Avendano , Roman Kogan , Mounir Nisse , J. Maurice Rojas

We show that the number of linear spaces on a set of $n$ points and the number of rank-3 matroids on a ground set of size $n$ are both of the form $(cn+o(n))^{n^2/6}$, where $c=e^{\sqrt 3/2-3}(1+\sqrt 3)/2$. This is the final piece of the…

Combinatorics · Mathematics 2024-05-31 Matthew Kwan , Ashwin Sah , Mehtaab Sawhney

We study a graded vector space of polynomials associated to a square matrix, defined by a finite difference condition along the rows. We show this space coincides with one defined by directional derivatives, and prove it is…

Combinatorics · Mathematics 2026-05-05 Tristram Bogart , Federico Castillo , Damián de la Fuente , David Plaza
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