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In this paper we study the concept of characteristic numbers and Chern slopes in the context of curve configurations in the real and complex projective plane. We show that some extremal line configurations inherit the same asymptotic…

Algebraic Geometry · Mathematics 2023-04-20 Adam Czapliński , Piotr Pokora

We report in this survey some new results concerning noncommutative Chern characters: construction and the cases when they are exactly computed. The major result indicates some clear relation of these noncommutative objects and their…

Quantum Algebra · Mathematics 2007-05-23 Do Ngoc Diep

This paper is devoted to settle two still open problems, connected with the existence of ample and nef divisors on a Q-factorial complete toric variety. The first problem is about the existence of ample divisors when the Picard number is 2:…

Algebraic Geometry · Mathematics 2018-04-16 Michele Rossi , Lea Terracini

We present the construction of a Chern character in cyclic cohomology, involving an arbitrary number of associative algebras in contravariant or covariant position. This is a generalization of the bivariant Chern character for bornological…

Mathematical Physics · Physics 2007-05-23 Denis Perrot

A simple formula is given for generating Chern characters by repeated exterior differentiation for n-dimensional differentiable manifolds having a general linear connection.

General Relativity and Quantum Cosmology · Physics 2007-05-23 C. C. Briggs

We give a complete classification of semistable rank two sheaves on three-dimensional projective space with maximal third Chern character. This implies an explicit description of their moduli spaces. As an open subset they contain rank two…

Algebraic Geometry · Mathematics 2018-11-30 Benjamin Schmidt

We study characteristic classes on hyperk\"ahler manifolds with a view towards the Verbitsky component. The case of the second Chern class leads to a conditional upper bound on the second Betti number in terms of the Riemann--Roch…

Algebraic Geometry · Mathematics 2022-08-09 Thorsten Beckmann , Jieao Song

We prove that the irreducible components of the characteristic varieties of quasi-projective manifolds are either pull-backs of such components for orbifolds, or torsion points. This gives an interpretation for the so-called…

Algebraic Geometry · Mathematics 2018-05-04 Enrique Artal Bartolo , Jose Ignacio Cogolludo-Agustin , Daniel Matei

It is proved that the degree of a morphism from a smooth projective n-fold with Picard number one to a smooth n-quadric is bounded (provided, of course, that n is at least three). Actually it has been proved some years ago, but I have never…

Algebraic Geometry · Mathematics 2007-05-23 Ekaterina Amerik

Some general expressions are given for the coefficient of the 14th Chern form in terms of the Riemann-Christoffel curvature tensor and some of its concomitants (e.g., Pontrjagin's characteristic tensors) for n-dimensional differentiable…

General Relativity and Quantum Cosmology · Physics 2007-05-23 C. C. Briggs

We study rank 2 torus-equivariant torsion-free sheaves on the complex projective space. For reflexive sheaves we derive a simple formula for the Chern polynomial, and in the general torsion-free case we introduce an iterative construction…

Algebraic Geometry · Mathematics 2025-11-07 Carl Tipler

In this paper, we establish a K\"ahlerian or projectivity criterion for a class of compact Hermitian surfaces with non-positive second Chern-Ricci curvature.

Differential Geometry · Mathematics 2024-07-09 Xiaokui Yang

We construct a canonical noncommutative spectral triple for every oriented closed Riemannian manifold, which represents the fundamental class in the twisted K-homology of the manifold. This so-called "projective spectral triple" is Morita…

Differential Geometry · Mathematics 2014-07-01 Dapeng Zhang

We prove the multiplicative property of localized Chern characters. As a direct consequence, a localized Chern character gives rise to a ring homomorphism from the K-group of periodic complexes to the bivariant Chow cohomology group. As an…

Algebraic Geometry · Mathematics 2025-04-22 Jeongseok Oh

According to Lerman, compact connected toric contact 3-manifolds with a non-free toric action whose moment cone spans an angle greater than $\pi$ are overtwisted, thus non-fillable. In contrast, we show that all compact connected toric…

Symplectic Geometry · Mathematics 2016-09-16 Aleksandra Marinkovic

For two complex vector bundles admitting a homomorphism, whose singularity locates in the disjoint union of some odd--dimensional spheres, we give a formula to compute the relative Chern characteristic number of these two complex vector…

Differential Geometry · Mathematics 2017-10-26 Dexie Lin

In this paper we investigate Fano manifolds $X$ whose Chern characters $ch_k(X)$ satisfy some positivity conditions. Our approach is via the study of polarized minimal families of rational curves $(H_x,L_x)$ through a general point $x\in…

Algebraic Geometry · Mathematics 2009-07-01 Carolina Araujo , Ana-Maria Castravet

We show that there exists a toric Fano manifold of dimension $10$ that does not admit an extremal K\"ahler metric in the first Chern class, answering a question of Mabuchi. By taking a product with a suitable toric Fano manifold, one can…

Algebraic Geometry · Mathematics 2024-12-09 DongSeon Hwang , Hiroshi Sato , Naoto Yotsutani

In this paper, we construct for higher twists that arise from cohomotopy classes, the Chern character in higher twisted K-theory, that maps into higher twisted cohomology. We show that it gives rise to an isomorphism between higher twisted…

Differential Geometry · Mathematics 2021-06-23 Lachlan Macdonald , Varghese Mathai , Hemanth Saratchandran

A rational linear combination of Chern numbers is an oriented diffeomorphism invariant of smooth complex projective varieties if and only if it is a linear combination of the Euler and Pontryagin numbers. In dimension at least three only…

Algebraic Geometry · Mathematics 2011-11-01 D. Kotschick