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A theory of characteristic classes of vector bundles and smooth manifolds plays an important role in the theory of smooth manifolds. An investigation of reasonable notions of characteristic classes of singular spaces started since a…

Algebraic Geometry · Mathematics 2007-05-23 Joerg Schuermann , Shoji Yokura

We introduce the AdditiveToricVarieties package for Macaulay2, a software system for algebraic geometry and commutative algebra, with methods for working with additive group actions on complete toric varieties. More precisely, we implement…

Algebraic Geometry · Mathematics 2026-02-25 Fabián Levicán-Santibáñez , Pedro Montero

For a complex variety with a torus action we propose a new method of computing Chern-Schwartz-MacPherson classes. The method does not apply resolution of singularities. It is based on Localization Theorem in equivariant cohomology.

Algebraic Geometry · Mathematics 2012-06-07 Andrzej Weber

Motivic integration and MacPherson's transformation are combined in this paper to construct a theory of "stringy" Chern classes for singular varieties. These classes enjoy strong birational invariance properties, and their definition…

Algebraic Geometry · Mathematics 2007-05-23 Tommaso de Fernex , Ernesto Lupercio , Thomas Nevins , Bernardo Uribe

Let $X_\Sigma$ be a smooth, not necessarily compact toric variety. We show that a certain complex, defined in terms of the fan $\Sigma$, computes the integral cohomology of $X_\Sigma$, including the module structure over the homology of the…

Algebraic Topology · Mathematics 2007-10-21 Matthias Franz

In this paper, we resolve a conjecture of Khovanskii--Monin on the Chern classes of toric variety bundles. The main result is a formula for the total Chern class of the tangent bundle of a toric variety bundle in terms of the total Chern…

Algebraic Geometry · Mathematics 2025-10-28 Gregory Taroyan

We introduce the notion of a multi-fan. It is a generalization of that of a fan in the theory of toric variety in algebraic geometry. Roughly speaking a toric variety is an algebraic variety with an action of algebraic torus of the same…

Symplectic Geometry · Mathematics 2007-05-23 Akio Hattori , Mikiya Masuda

Let X be a normal projective Q-Gorenstein variety with at worst log-terminal singularities. We prove a formula expressing the total stringy Chern class of a generic complete intersection in X via the total stringy Chern class of X. This…

Algebraic Geometry · Mathematics 2016-07-20 Victor Batyrev , Karin Schaller

The Macaulay2 package CharacteristicClasses provides commands for the computation of the topological Euler characteristic, the degrees of the Chern classes and the degrees of the Segre classes of a closed subscheme of complex projective…

Algebraic Geometry · Mathematics 2013-01-21 Christine Jost

In the present work we give a description a computer algebra algorithm of construction of a toric variety given its fan. The algorithm provides us as well with a construction of an integral representation in $\mathbb{C}^d$, associated with…

Complex Variables · Mathematics 2010-03-30 Alexey A Kytmanov

We define the Chow ring of the classifying space of a linear algebraic group. In all the examples where we can compute it, such as the symmetric groups and the orthogonal groups, it is isomorphic to a natural quotient of the complex…

Algebraic Geometry · Mathematics 2007-05-23 Burt Totaro

Open Gromov-Witten invariants in general are not well-defined. We discuss in detail the enumerative numbers of the Clifford torus $T^2$ in $\CP^2$. For cyclic A-infinity algebras, we show that certain generalized way of counting may be…

Symplectic Geometry · Mathematics 2014-03-19 Cheol-Hyun Cho

Associated to a toric variety $X$ of dimension $r$ over a field $k$ is a fan $\Delta$ on $\Bbb R^r$. The fan $\Delta$ is a finite set of cones which are in one-to-one correspondence with the orbits of the torus action on $X$. The fan…

alg-geom · Mathematics 2008-02-03 Timothy J. Ford

Let $\mathcal{M}$ be the moduli space of rank 2 stable torsion free sheaves with Chern classes $c_i$ on a smooth 3-fold $X$. When $X$ is toric with torus $T$, we describe the $T$-fixed locus of the moduli space. Connected components of…

Algebraic Geometry · Mathematics 2018-06-18 Amin Gholampour , Martijn Kool , Benjamin Young

Let $V$ be a closed subscheme of a projective space $\mathbb{P}^n$. We give an algorithm to compute the Chern-Schwartz-MacPherson class, Euler characteristic and Segre class of $ V$. The algorithm can be implemented using either symbolic or…

Algebraic Geometry · Mathematics 2016-03-24 Martin Helmer

Homology Hirzebruch characteristic classes for singular varieties have been recently defined by Brasselet-Schuermann-Yokura as an attempt to unify previously known characteristic class theories for singular spaces (e.g., MacPherson-Chern…

Algebraic Geometry · Mathematics 2016-05-24 Sylvain E. Cappell , Laurentiu Maxim , Joerg Schuermann , Julius L. Shaneson

This paper gives computations of all the $G$-theory groups of several classes of simplicial toric varieties, including all affine toric surfaces when the base field is algebraically closed and has characteristic zero, all weighted…

Algebraic Geometry · Mathematics 2025-09-09 Zeyu Shen

In this paper we study some new theories of characteristic homology classes for singular complex algebraic (or compactifiable analytic) spaces. We introduce a motivic Chern class transformation mC_{*}: K_{0}(var/X)-> G_{0}(X)[y], which…

Algebraic Geometry · Mathematics 2007-05-23 Jean-Paul Brasselet , Joerg Schuermann , Shoji Yokura

We develop a theory of arithmetic characteristic classes of (fully decomposed) automorphic vector bundles equipped with an invariant hermitian metric. These characteristic classes have values in an arithmetic Chow ring constructed by means…

Algebraic Geometry · Mathematics 2007-05-23 J. I. Burgos Gil , J. Kramer , U. Kuehn

Given a hypersurface in a complex projective space, we prove that the multidegrees of its toric polar map agree, up to sign, with the coefficients of the Chern-Schwartz-MacPherson class of a distinguished open set, namely the complement of…

Algebraic Geometry · Mathematics 2023-05-03 Thiago Fassarella , Nivaldo Medeiros , Rodrigo Salomão