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In this paper, we give the complete classification of full exceptional collections on smooth toric Fano threefolds and fourfolds with Picard rank two. To be precise, we give a partial answer to the conjecture in \cite{Kuz} and \cite{LYY}:…

Algebraic Geometry · Mathematics 2023-03-08 Dae-Won Lee

In this paper we provide a characterization of smooth algebraic varieties endowed with a faithful algebraic torus action in terms of a combinatorial description given by Altmann and Hausen. Our main result is that such a variety X is smooth…

Algebraic Geometry · Mathematics 2016-06-22 Alvaro Liendo , Charlie Petitjean

This note introduces the $\texttt{LikelihoodGeometry}$ package for the computer algebra system $\textit{Macaulay2}$. This package gives tools to construct the likelihood correspondence of a discrete algebraic statistical model, a variety…

Computation · Statistics 2024-11-19 David Barnhill , John Cobb , Matthew Faust

An induced additive action on a projective variety $X\subseteq\mathbb{P}^n$ is a regular action of the group $\mathbb{G}_a^n$ on $X$ with an open orbit that can be extended to a regular action on $\mathbb{P}^n$. Such actions are known to…

Algebraic Geometry · Mathematics 2026-05-01 Alexander Chernov

In this paper, we study complete simplicial toric varieties admitting faithful actions of large symmetric groups. First, we correct a recent classification result by Esser, Ji, and Moraga concerning $4$-dimensional toric varieties with…

Algebraic Geometry · Mathematics 2026-04-28 Yutaro Naito

This paper constructs tilting bundles obtained from full strong exceptional collections of line bundles on all smooth $4$-dimensional toric Fano varieties. The tilting bundles lead to a large class of explicit Calabi-Yau-$5$ algebras,…

Algebraic Geometry · Mathematics 2015-01-27 Nathan Prabhu-Naik

We present the Macaulay2 package TropicalToric.m2 for toric intersection theory computations using tropical geometry.

Algebraic Geometry · Mathematics 2024-03-27 Alessio Borzì

This note describes a Macaulay2 package for handling divisors. Group operations for divisors are included. There are methods for converting divisors to reflexive or invertible sheaves. Additionally, there are methods for checking whether…

Algebraic Geometry · Mathematics 2019-06-25 Karl Schwede , Zhaoning Yang

The Macaulay2 package Cremona performs some computations on rational and birational maps between irreducible projective varieties. For instance, it provides methods to compute degrees and projective degrees of rational maps without any…

Algebraic Geometry · Mathematics 2018-08-28 Giovanni Staglianò

We give an explicit description of all smooth varieties with a torus action of complexity one having Picard number at most two. As a consequence, we classify in every dimension the smooth (almost) Fano varieties with a torus action of…

Algebraic Geometry · Mathematics 2025-07-08 Anne Fahrner , Juergen Hausen , Michele Nicolussi

We introduce the DeterminantalRepresentations package for Macaulay2, which computes definite symmetric determinantal representations of real polynomials. We focus on quadrics and plane curves of low degree (i.e. cubics and quartics). Our…

Algebraic Geometry · Mathematics 2020-02-12 Justin Chen , Papri Dey

The {\tt Macaulay2} package {\tt RandomMonomialIdeals} provides users with a set of tools that allow for the systematic generation and study of random monomial ideals. It also introduces new objects, Sample and Model, to allow for…

Commutative Algebra · Mathematics 2019-10-16 Sonja Petrović , Despina Stasi , Dane Wilburne

The signature of a path is a non-commutative power series whose coefficients are given by certain iterated integrals over the path coordinates. This series almost uniquely characterizes the path up to translation and reparameterization.…

Algebraic Geometry · Mathematics 2026-05-27 Carlos Améndola , Angelo El Saliby , Felix Lotter , Oriol Reig Fité

We introduce the \verb|Macaulay2| package \verb|RepHomology| for the computations of representation homology of certain spaces. The main methods implement computing the representation homology of surfaces (with group coefficients, and…

Algebraic Geometry · Mathematics 2024-10-25 Guanyu Li

We show the existence of an equivariant weight filtration on the equivariant homology of real algebraic varieties equipped with a finite group action, by applying group homology onto the weight complex of McCrory and Parusi\'nski. The group…

Algebraic Geometry · Mathematics 2017-03-09 Fabien Priziac

We investigate full strongly exceptional collections on smooth, com- plete toric varieties. We obtain explicit results for a large family of varieties with Picard number three, containing many of the families already known. We also describe…

Algebraic Geometry · Mathematics 2021-04-06 Michal Lason , Mateusz Michalek

We consider subtorus actions on divisorial toric varieties. Here divisoriality means that the variety has many Cartier divisors like quasiprojective and smooth ones. We characterize when a subtorus action on such a toric variety admits a…

Algebraic Geometry · Mathematics 2007-05-23 A. A'Campo-Neuen , J. Hausen

We provide a systematic method to classify all smooth weak Fano toric varieties of Picard rank $3$ in any dimension using Macaulay2, and describe the classification explicitly in dimensions $3$ and $4$. There are $28$ and $114$ isomorphism…

Algebraic Geometry · Mathematics 2025-06-03 Zhengning Hu , Rohan Joshi

Toric varieties are a special class of rational varieties defined by equations of the form {\it monomial = monomial}. For a good brief survey of the history and role of toric varieties see [10]. Any toric variety $X$ contains a cover by…

alg-geom · Mathematics 2008-02-03 Frank DeMeyer , Tim Ford , Rick Miranda

In this paper, we classify smooth, contractible affine varieties equipped with faithful torus actions of complexity two, having a unique fixed point and a two-dimensional algebraic quotient isomorphic to a toric blow-up of a toric surface.…

Algebraic Geometry · Mathematics 2024-11-25 Alvaro Liendo , Charlie Petitjean