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The stable rationality of components of the moduli space of (unparametrized) rational curves in projective $n$-space with fixed normal bundle is proved, provided these components dominate the moduli space of immersed rational curves in the…

Algebraic Geometry · Mathematics 2007-05-23 Herbert Clemens

We describe deformations of vector bundles on surfaces that are a product of two smooth projective curves. We explicitly describe the Kuranishi map around unstable vector bundles and compare the homologies of the Kuranishi spaces of stable…

Algebraic Geometry · Mathematics 2023-11-14 Edoardo Ballico , Elizabeth Gasparim , Francisco Rubilar , Bruno Suzuki

Let X be a smooth projective curve of genus at least two over the complex numbers. A pair (E,\phi) over X consists of an algebraic vector bundle E over X and a holomorphic section \phi of E. There is a concept of stability for pairs which…

Algebraic Geometry · Mathematics 2015-05-13 Vicente Munoz

We study the spaces of stable real and quaternionic vector bundles on a real algebraic curve. The basic relationship is established with unitary representations of an extension Z/2 by the fundamental group. By comparison with the space of…

Algebraic Geometry · Mathematics 2009-04-03 Indranil Biswas , Johannes Huisman , Jacques C. Hurtubise

In this article we study the behaviour of semistable principal $G$-bundles over a smooth projective variety $X$ under the extension of structure groups in positive characteristic. We extend some results of Ramanan-Ramanathan…

Algebraic Geometry · Mathematics 2007-05-23 Fabrizio Coiai , Yogish I. Holla

In this article, we investigate the stability of syzygy bundles corresponding to ample and globally generated vector bundles on smooth irreducible projective surfaces.

Algebraic Geometry · Mathematics 2024-05-28 Snehajit Misra , Nabanita Ray

Faltings conjectured that under the p-adic Simpson correspondence, finite dimensional p-adic representations of the geometric \'etale fundamental group of a smooth proper p-adic curve X are equivalent to semi-stable Higgs bundles of degree…

Algebraic Geometry · Mathematics 2025-01-28 Daxin Xu

Roughly speaking, a conic bundle is a surface, fibered over a curve, such that the fibers are conics (not necessarily smooth). We define stability for conic bundles and construct a moduli space. We prove that (after fixing some invariants)…

Algebraic Geometry · Mathematics 2007-05-23 T. Gomez , I. Sols

In this paper, we consider a generalization of the theory of Higgs bundles over a smooth complex projective curve in which the twisting of the Higgs field by the canonical bundle of the curve is replaced by a rank 2 vector bundle. We define…

Algebraic Geometry · Mathematics 2024-06-26 Guillermo Gallego , Oscar Garcia-Prada , M. S. Narasimhan

In this article, we investigate Hecke modifications of vector bundles on a smooth projective curve $X$ defined over an arbitrary field. We obtain structural results that allow us to reduce the classification problem of Hecke modifications…

Algebraic Geometry · Mathematics 2025-06-03 Roberto Alvarenga , Leonardo Moço

We prove that the normal bundle of a general Brill-Noether curve of genus $g \geq 1$ and degree $d$ in $\mathbb{P}^r$ is semistable if $g=1$ or $g\geq \left \lceil \frac{5r}{2}\right\rceil r(r-1)$, or $d$ is larger than an explicit function…

Algebraic Geometry · Mathematics 2024-11-27 Izzet Coskun , Geoffrey Smith

We consider stable and semistable principal bundles over a smooth projective real algebraic curve, equipped with a real or pseudo-real structure in the sense of Atiyah. After fixing suitable topological invariants, one can build a suitable…

Algebraic Geometry · Mathematics 2015-09-29 Indranil Biswas , Oscar Garcia-Prada , Jacques Hurtubise

Let $X$ be an $(8k+i)$-dimensional pathwise connected $CW$-complex with $i=1$ or $2$ and $k\ge0$, $\xi$ be a real vector bundle over $X$. Suppose that $\xi$ admits a stable complex structure over the $8k$-skeleton of $X$. Then we get that…

Algebraic Topology · Mathematics 2016-03-22 Huijun Yang

Classification theory and the study of projective varieties which are covered by rational curves of minimal degrees naturally leads to the study of families of singular rational curves. Since families of arbitrarily singular curves are hard…

Algebraic Geometry · Mathematics 2007-05-23 Stefan Kebekus

Using combinatorial methods, we determine that a projective coordinate ring of the moduli of parabolic principal $\mathrm{SL}_2$-bundles on a marked projective curve is not Gorenstein when the genus and number of marked points are greater…

Algebraic Geometry · Mathematics 2019-08-27 Theodore Faust , Christopher Manon

Let $Y_{1},\dots,Y_{l}$ be smooth irreducible projective curves and let $Y$ be its disjoint union. Given a semisimple reductive algebraic group $G$ and a faithful representation $\rho:G\hookrightarrow \textrm{SL}(V)$ we construct a…

Algebraic Geometry · Mathematics 2020-07-28 Ángel Luis Muñoz Castañeda

In this paper, we establish characterizations of variational $s$-convexity and tilt stability for prox-regular functions in the absence of subdifferential continuity via quadratic bundles, a kind of primal-dual generalized second-order…

Optimization and Control · Mathematics 2025-01-09 Pham Duy Khanh , Boris S. Mordukhovich , Vo Thanh Phat , Le Duc Viet

Let $C$ be a curve with two smooth components and a single node. Let $\mathcal{U}_C(r,w,\chi)$ be the moduli space of $w$-semistable classes of depth one sheaves on $C$ having rank $r$ on both components and Euler characteristic $\chi$. In…

Algebraic Geometry · Mathematics 2020-07-29 Sonia Brivio , Filippo F. Favale

Let H be a semisimple algebaric group and let X be a smooth projective curve defined over an algebraically closed field k. In the first part of this paper we show that the moduli of semistable principal H-bundles exists once given a…

Algebraic Geometry · Mathematics 2007-05-23 V. Balaji , A. J. Parameswaran

We describe the locus of stable bundles on a smooth genus $g$ curve that fail to be globally generated. For each rank $r$ and degree $d$ with $rg<d<r(2g-1)$, we exhibit a component of the expected dimension. We show moreover that no…

Algebraic Geometry · Mathematics 2021-10-14 John Kopper , Sayanta Mandal