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We develop a theory of general sheaves over weighted projective lines. We define and study a canonical decomposition, analogous to Kac's canonical decomposition for representations of quivers, study subsheaves of a general sheaf, general…

Algebraic Geometry · Mathematics 2007-09-24 William Crawley-Boevey

Using the concept of a cohesive module defined by Block, we use the theory of superconnections in the sense of Quillen to construct natural superconnections on Hermitian cohesive modules. By the Chern-Weil construction, we obtain…

Differential Geometry · Mathematics 2016-11-15 Hua Qiang

We start developing a notion of reciprocity sheaves, generalizing Voevodsky's homotopy invariant presheaves with transfers which were used in the construction of his triangulated categories of motives. We hope reciprocity sheaves will…

Algebraic Geometry · Mathematics 2019-02-20 Bruno Kahn , Shuji Saito , Takao Yamazaki

Coherent sheaves on general complex manifolds do not necessarily have resolutions by finite complexes of vector bundles. However D. Toledo and Y.L.L. Tong showed that one can resolve coherent sheaves by objects analogous to chain complexes…

Algebraic Topology · Mathematics 2025-01-01 Cheyne Glass , Micah Miller , Thomas Tradler , Mahmoud Zeinalian

We construct a groupoid equivariant Kasparov class for transversely oriented foliations in all codimensions. In codimension 1 we show that the Chern character of an associated semifinite spectral triple recovers the Connes-Moscovici cyclic…

K-Theory and Homology · Mathematics 2020-06-24 Lachlan MacDonald , Adam Rennie

This is the second in a series of papers. Here we develop here an intersection theory for manifolds equipped with an action of a finite group. As in our previous paper, our approach will be homotopy theoretic, enabling us to circumvent the…

Algebraic Topology · Mathematics 2009-01-23 John R. Klein , Bruce Williams

Richardson varieties play an important role in intersection theory and in the geometric interpretation of the Littlewood-Richardson Rule for flag varieties. We discuss three natural generalizations of Richardson varieties which we call…

Algebraic Geometry · Mathematics 2010-08-18 Sara Billey , Izzet Coskun

The classical Chern correspondence states that a choice of Hermitian metric on a holomorphic vector bundle determines uniquely a unitary 'Chern connection'. This basic principle in Hermitian geometry, later generalized to the theory of…

Differential Geometry · Mathematics 2023-10-20 Roberto Tellez-Dominguez

The Chern class of the sheaf of logarithmic derivations along a simple normal crossing divisor equals the Chern-Schwartz-MacPherson class of the complement of the divisor. We extend this equality to more general divisors, which are locally…

Algebraic Geometry · Mathematics 2013-03-04 Paolo Aluffi

We introduce the semi-infinite category of sheaves on the affine Grassmannian, and construct a particular object in it, which we call the the semi-infinite intersection cohomology sheaf. We relate it to several other entities naturally…

Algebraic Geometry · Mathematics 2021-11-02 Dennis Gaitsgory

We obtain criteria for detecting complete intersections in projective varieties. Motivated by a conjecture of Hartshorne concerning subvarieties of projective spaces, we investigate situations when two-codimensional smooth subvarieties of…

Algebraic Geometry · Mathematics 2020-12-01 Mihai Halic

In this article we develop intersection theory in terms of the $\mathcal{B}$-group of a reduced analytic space. This group was introduced in a previous work as an analogue of the Chow group; it is generated by currents that are direct…

Algebraic Geometry · Mathematics 2019-09-02 Mats Andersson , Dennis Eriksson , Håkan Samuelsson Kalm , Elizabeth Wulcan , Alain Yger

In "Chern classes for coherent sheaves", H.I. Green constructs Chern classes in de Rham cohomology of coherent analytic sheaves. We construct here a formal $(\infty,1)$-categorical framework into which we can place Green's work and…

Algebraic Geometry · Mathematics 2023-06-28 Timothy Hosgood

A semiring scheme generalizes a scheme in such a way that the underlying algebra is that of semirings. We generalize \v{C}ech cohomology theory and invertible sheaves to semiring schemes. In particular, when $X=\mathbb{P}^n_M$, a projective…

Algebraic Geometry · Mathematics 2015-06-22 Jaiung Jun

We prove a universal property for the $(\infty, n)$-category of correspondences, generalizing and providing a new proof for the case $n = 2$ from [GR17]. We also provide conditions under which a functor out of a higher category of…

Algebraic Topology · Mathematics 2020-11-06 Germán Stefanich

We introduce trim resolutions of complex algebraic varieties, a strengthening of the notion of small resolution. We prove that the characteristic cycle of the intersection cohomology sheaf of a variety admitting a trim resolution is…

Algebraic Geometry · Mathematics 2025-12-10 Paolo Aluffi

We develop a generalization to non-Witt spaces of the intersection homology theory of Goresky-MacPherson. The second author has described the self-dual sheaves compatible with intersection homology, and the other authors have described a…

Geometric Topology · Mathematics 2013-08-20 Pierre Albin , Markus Banagl , Eric Leichtnam , Rafe Mazzeo , Paolo Piazza

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 paper is a part of our program to build up a theory of couting immersed nodal curve on algebraic surfaces, as an enumerative Riemann-Roch theory (outlined in math.AG/0405113). In this paper, we discuss the excess intersection theory of…

Algebraic Geometry · Mathematics 2016-09-07 Ai-Ko Liu

We introduce Chern classes in $U(m)$-equivariant homotopical bordism that refine the Conner-Floyd-Chern classes in the $MU$-cohomology of $B U(m)$. For products of unitary groups, our Chern classes form regular sequences that generate the…

Algebraic Topology · Mathematics 2024-01-08 Stefan Schwede