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It is expected that a totally invariant divisor of a non-isomorphic endomorphism of the complex projective space is a union of hyperplanes. In this paper, we compute an upper bound for the degree of such a divisor. As a consequence, we…

Algebraic Geometry · Mathematics 2021-11-30 Mabed Yanis

A result of Beauville states that with a few positive characterstic exceptions, the smooth hyperplane sections of hypersurfaces of degree $d>2$ in projective space are not all isomorphic. We address the question of whether these sections…

Algebraic Geometry · Mathematics 2007-05-23 Michael A. van Opstall , Razvan Veliche

We compute some numerical invariants of the lines on hyperplane sections of a smooth cubic threefold over complex numbers. We also prove that for any smooth hypersurface $X\subset \mathbb P^{n+1}$ of degree $d$ over an algebraically closed…

Algebraic Geometry · Mathematics 2020-07-08 Yiran Cheng

We prove that every projective variety of dimension n over a field of positive characteristic admits a morphism to projective n-space, etale away from the hyperplane H at infinity, which maps a chosen divisor into H and a chosen smooth…

Algebraic Geometry · Mathematics 2007-05-23 Kiran S. Kedlaya

In this paper we describe projective curves and surfaces such that almost all their hyperplane sections are projectively equivalent. Our description is complete for curves and close to being complete for smooth surfaces. In the appendix we…

alg-geom · Mathematics 2008-02-03 S. L'vovsky

Ballico proved that a smooth projective variety $X$ of degree $d$ over a finite field of $q$ elements admits a smooth hyperplane section if $q\geq d(d-1)^{\dim X}$. In this paper, we refine this criterion for higher codimensional linear…

Algebraic Geometry · Mathematics 2024-02-28 Shamil Asgarli , Lian Duan , Kuan-Wen Lai

We consider surjective endomorphisms f of degree > 1 on the projective n-space with n = 3, and f^{-1}-stable hypersurfaces V. We show that V is a hyperplane (i.e., deg(V) = 1) but with four possible exceptions; it is conjectured that deg(V)…

Algebraic Geometry · Mathematics 2018-06-20 De-Qi Zhang

We prove that a general hyperplane section of a smooth Legendrian subvariety in a projective space admits Legendrian embedding into another projective space. This gives numerous new examples of smooth Legendrian subvarieties, some of which…

Algebraic Geometry · Mathematics 2010-01-20 Jaroslaw Buczynski

We obtain a complete list of smooth projective threefolds over $\mathbb C$ for which the dimension of the space of vanishing cycles (in $H^2$ of the smooth hyperplane section) equals $2$. We also obtain a complete list of rank 2 very ample…

Algebraic Geometry · Mathematics 2025-06-03 Timofey Fedorov

We show that there is a smooth complex projective variety, of any dimension greater than or equal to two, whose automorphism group is discrete and not finitely generated. Moreover, this variety admits infinitely many real forms which are…

Algebraic Geometry · Mathematics 2019-05-29 Tien-Cuong Dinh , Keiji Oguiso

We prove that every geometrically reduced projective variety of pure dimension n over a field of positive characteristic admits a morphism to projective n-space, etale away from the hyperplane H at infinity, which maps a chosen divisor into…

Algebraic Geometry · Mathematics 2007-05-23 Kiran S. Kedlaya

We first show that any connected algebraic group over a perfect field is the neutral component of the automorphism group scheme of some normal projective variety. Then we show that very few connected algebraic semigroups can be realized as…

Algebraic Geometry · Mathematics 2013-12-23 Michel Brion

Let X be a smooth cubic hypersurface. We prove that a general cubic surface is isomorphic to a hyperplane section of X .

Algebraic Geometry · Mathematics 2025-03-28 Arnaud Beauville

let f be an endomorphism of a complex projective space, of degree bigger than one. Let us call an algebraic subset exceptional for f, if its inverse image is set-theoretically equal to itself. J.-Y. Briend, S. Cantat and M. Shishikura…

Algebraic Geometry · Mathematics 2007-05-23 E. Amerik , F. Campana

We show that for every morphism f between nonsingular hypersurfaces of dimension at least 3 and of general type in projective space, there is an everywhere defined endomorphism F of projective space that restricts to f. As a corollary, we…

Algebraic Geometry · Mathematics 2007-05-23 David Sheppard

It is shown that a complex normal projective variety has non-positive Kodaira dimension if it admits a non-isomorphic quasi-polarized endomorphism. The geometric structure of the variety is described by methods of equivariant lifting and…

Algebraic Geometry · Mathematics 2018-09-24 Noboru Nakayama , De-Qi Zhang

We prove that every endomorphism of an infinite-dimensional vector space splits as the sum of four idempotents and as the sum of four square-zero endomorphisms, a result that is optimal in general.

Rings and Algebras · Mathematics 2016-09-27 Clément de Seguins Pazzis

Totally invariant divisors of endomorphisms of the projective space are expected to be always unions of linear spaces. Using logarithmic differentials we establish a lower bound for the degree of the non-normal locus of a totally invariant…

Algebraic Geometry · Mathematics 2017-10-18 Andreas Höring

We prove that a component of the closure of the set of star points on a hypersurface X of degree d>2 in N-dimensional projective space is linear. Afterwards, we focus on the case where the component is of maximal dimension N-2 and the case…

Algebraic Geometry · Mathematics 2009-09-10 Filip Cools , Marc Coppens

A subspace $X$ of a vector space over a field $K$ is hyperinvariant with respect to an endomorphism $f$ of $V$ if it is invariant for all endomorphisms of $V$ that commute with $f$. We assume that $f$ is locally nilpotent, that is, every $…

Rings and Algebras · Mathematics 2015-11-25 Pudji Astuti , Harald K. Wimmer
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