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We give an algorithm for computing Segre classes of subschemes of arbitrary projective varieties by computing degrees of a sequence of linear projections. Based on the fact that Segre classes of projective varieties commute with…

Algebraic Geometry · Mathematics 2015-11-30 Corey Harris

We present a method to compute the degrees of the Segre classes of a subscheme of complex projective space. The method is based on generic residuation and intersection theory. It has been implemented using the software system Macaulay2.

Algebraic Geometry · Mathematics 2016-04-13 David Eklund , Christine Jost , Chris Peterson

We express the Segre class of a monomial scheme -- or, more generally, a scheme monomially supported on a set of divisors cutting out complete intersections -- in terms of an integral computed over an associated body in euclidean space. The…

Algebraic Geometry · Mathematics 2021-02-08 Paolo Aluffi

We provide a generalization of the algorithm of Eklund-Jost-Peterson for computing Segre classes of closed subschemes of projective k-space. The algorithm is here generalized to computing the Segre classes of closed subschemes of smooth…

Algebraic Geometry · Mathematics 2014-04-01 Torgunn Karoline Moe , Nikolay Qviller

Let $X_{\Sigma}$ be a smooth complete toric variety defined by a fan $\Sigma$ and let $V=V(I)$ be a subscheme of $X_{\Sigma}$ defined by an ideal $I$ homogeneous with respect to the grading on the total coordinate ring of $X_{\Sigma}$. We…

Algebraic Geometry · Mathematics 2017-11-15 Martin Helmer

Segre classes encode essential intersection-theoretic information concerning vector bundles and embeddings of schemes. In this paper we survey a range of applications of Segre classes to the definition and study of invariants of singular…

Algebraic Geometry · Mathematics 2025-04-02 Paolo Aluffi

Suppose $X$ is a closed sub-scheme of $Y$ and $Y$ is a closed sub-scheme of $Z$ that formally locally has an analog of a tubular neighborhood in a sense that we define in the paper. In this setting, we prove a formula for calculating the…

Algebraic Geometry · Mathematics 2015-03-06 Daniel Lowengrub

We prove an identity of Segre classes for zero-schemes of compatible sections of two vector bundles. Applications include bounds on the number of equations needed to cut out a scheme with the same Segre class as a given subscheme of (for…

Algebraic Geometry · Mathematics 2016-10-18 Paolo Aluffi

We propose an explicit formula for the Segre classes of monomial subschemes of nonsingular varieties, such as schemes defined by monomial ideals in projective space. The Segre class is expressed as a formal integral on a region bounded by…

Algebraic Geometry · Mathematics 2013-07-04 Paolo Aluffi

There is an explicit formula expressing the Chern-Schwartz-MacPherson class of a hypersurface in a nonsingular variety (in characteristic $0$) in terms of the Segre class of its jacobian subscheme; this has been known for a number of years.…

Algebraic Geometry · Mathematics 2019-10-30 Paolo Aluffi

Given a flat, projective morphism $Y \to T$ from an equidimensional scheme to a nonsingular curve and a subscheme $Z$ of $Y$, we give conditions under which specialization of the Segre class $s(N_{Z}Y)$ of the normal cone of $Z$ in $Y$…

Algebraic Geometry · Mathematics 2007-05-23 S. J. Colley , G. Kennedy

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

We study a class obtained from the Segre class $s(Z,Y)$ of an embedding of schemes by incorporating the datum of a line bundle on $Z$. This class satisfies basic properties analogous to the ordinary Segre class, but leads to remarkably…

Algebraic Geometry · Mathematics 2018-01-25 Paolo Aluffi

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

We describe a computational proof that the fifth secant variety of the Segre product of five copies of the projective line is a codimension 2 complete intersection of equations of degree 6 and 16. Our computations rely on pseudo-randomness,…

Algebraic Geometry · Mathematics 2015-10-19 Luke Oeding , Steven V Sam

We study the linear algebra of finite subsets $S$ of a Segre variety $X$. In particular we classify the pairs $(S,X)$ with $S$ linear dependent and $\#(S)\le 5$. We consider an additional condition for linear dependent sets (no two of their…

Algebraic Geometry · Mathematics 2020-02-14 Edoardo Ballico

Let K=Fq be a finite field. We introduce a family of projective Reed-Muller-type codes called projective Segre codes. Using commutative algebra and linear algebra methods, we study their basic parameters and show that they are direct…

Commutative Algebra · Mathematics 2016-01-28 Azucena Tochimani , Maria Vaz Pinto , Rafael H. Villarreal

We derive a formula for the Milnor class of scheme-theoretic global complete intersections (with arbitrary singularities) in a smooth variety in terms of the Segre class of its singular scheme. In codimension one the formula recovers a…

Algebraic Geometry · Mathematics 2013-11-19 James Fullwood

We generalize the Chern class relation for the transversal intersection of two nonsingular varieties to a relation for possibly singular varieties, under a 'splayedness' assumption. The relation is shown to hold for both the…

Algebraic Geometry · Mathematics 2019-08-15 Paolo Aluffi , Eleonore Faber

On a reduced analytic space $X$ we introduce the concept of a generalized cycle, which extends the notion of a formal sum of analytic subspaces to include also a form part. We then consider a suitable equivalence relation and corresponding…

Complex Variables · Mathematics 2020-03-16 Mats Andersson , Dennis Eriksson , Håkan Samuelsson Kalm , Elizabeth Wulcan , Alain Yger
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