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We prove the failure of stable rationality for many smooth well formed weighted hypersurfaces of dimension at least 3. It is in particular proved that a very general smooth well formed Fano weighted hypersurface of index one is not stably…

Algebraic Geometry · Mathematics 2017-09-26 Takuzo Okada

We determine the rationality of very general quasismooth Fano 3-fold weighted hypersurfaces completely and determine the stable rationality of them except for cubic 3-folds. More precisely we prove that (i) very general Fano 3-fold weighted…

Algebraic Geometry · Mathematics 2017-09-25 Takuzo Okada

We show that a wide class of hypersurfaces in all dimensions are not stably rational. Namely, for all d at least about 2n/3, a very general complex hypersurface of degree d in P^{n+1} is not stably rational. The statement generalizes…

Algebraic Geometry · Mathematics 2015-06-16 Burt Totaro

Let k be an uncountable field of characteristic different from two. We show that a very general hypersurface of dimension N>2 and degree at least $\log_2N +2$ is not stably rational over the algebraic closure of k.

Algebraic Geometry · Mathematics 2019-10-23 Stefan Schreieder

We study rational surfaces on very general Fano hypersurfaces in $\mathbb{P}^n$, with an eye toward unirationality. We prove that given any fixed family of rational surfaces, a very general hypersurface of degree $d$ sufficiently close to…

Algebraic Geometry · Mathematics 2022-07-01 Roya Beheshti , Eric Riedl

We introduce an inductive argument for proving birational superrigidity and K-stability of singular Fano complete intersections of index one, using the same types of information from lower dimensions. In particular, we prove that a…

Algebraic Geometry · Mathematics 2021-08-30 Yuchen Liu , Ziquan Zhuang

Extending previous results, we prove that for $n \ge 5$ all hypersurfaces of degree $n+1$ in ${\mathbb P}^{n+1}$ with isolated ordinary double points are birational superrigid and K-stable, hence admit a weak K\"ahler--Einstein metric.

Algebraic Geometry · Mathematics 2022-01-19 Tommaso de Fernex

In this note, we study various measures of irrationality for hypersurfaces in projective spaces which were recently proposed by Bastianelli, De Poi, Ein, Lazarsfeld and Ullery. In particular, we answer the question raised by Bastianelli…

Algebraic Geometry · Mathematics 2020-10-19 Ruijie Yang

A very general hypersurface of dimension $n$ and degree $d$ in complex projective space is rational if $d \leq 2$, but is expected to be irrational for all $n, d \geq 3$. Hypersurfaces in weighted projective space with degree small relative…

Algebraic Geometry · Mathematics 2024-11-20 Louis Esser

We give the first evidence for a conjecture that a general, index-one, Fano hypersurface is not unirational: (i) a general point of the hypersurface is contained in no rational surface ruled, roughly, by low-degree rational curves, and (ii)…

Algebraic Geometry · Mathematics 2007-05-23 Roya Beheshti , Jason Michael Starr

Fix positive integers $n,r,d$. We show that if $n,r,d$ satisfy a suitable inequality, then any smooth hypersurface $X\subset \mathbb{P}^n$ defined over a finite field of characteristic $p$ sufficiently large contains a rational $r$-plane.…

Algebraic Geometry · Mathematics 2021-11-23 María Inés de Frutos Fernández , Sumita Garai , Kelly Isham , Takumi Murayama , Geoffrey Smith

Using Voisin's method we prove that a very general hypersurface of degree at least 4 in complex projective space of dimension 6, 7, 8 or 9 is not stably rational and so, in particular, not rational. We obtain the same conclusion for the…

Algebraic Geometry · Mathematics 2015-12-23 Stefan Schreieder , Luca Tasin

We show that complex Fano hypersurfaces can have arbitrarily large degrees of irrationality. More precisely, if we fix a Fano index e, then the degree of irrationality of a very general complex Fano hypersurface of index e and dimension n…

Algebraic Geometry · Mathematics 2021-11-11 Nathan Chen , David Stapleton

The main aim of this paper is to show that a cyclic cover of $\mathbb{P}^n$ branched along a very general divisor of degree $d$ is not stably rational provided that $n \ge 3$ and $d \ge n+1$. This generalizes the result of…

Algebraic Geometry · Mathematics 2019-07-10 Takuzo Okada

We show that a very general hypersurface of degree d at least 4 and dimension at most $(d+1)2^{d-4}$ over a field of characteristic different from 2 does not admit a decomposition of the diagonal; hence, it is neither stably nor retract…

Algebraic Geometry · Mathematics 2026-01-14 Jan Lange , Stefan Schreieder

We show that the degrees of rational endomorphisms of very general complex Fano and Calabi-Yau hypersurfaces satisfy certain congruence conditions by specializing to characteristic p. As a corollary we show that very general n-dimensional…

Algebraic Geometry · Mathematics 2022-05-20 Nathan Chen , David Stapleton

Over fields of characteristic zero, we show that for $n=1,d\geq4$ or $n=2,d\geq5$ or $n\geq3, d\geq 2n$, the generic $m$-marked degree-$d$ hypersurface in $\mathbb{P}^{n+1}$ admits the $m$ marked points as all the rational points. Over…

Algebraic Geometry · Mathematics 2023-09-22 Qixiao Ma

For sufficiently ample linear systems on rational surfaces we show that a very general associated Brauer-Severi surface bundle is not stably rational.

Algebraic Geometry · Mathematics 2017-10-02 Andrew Kresch , Yuri Tschinkel

We prove that a very general hypersurface of bidegree (2, n) in P^2 x P^2 for n bigger than or equal to 2 is not stably rational, using Voisin's method of integral Chow-theoretic decompositions of the diagonal and their preservation under…

Algebraic Geometry · Mathematics 2016-05-18 Christian Böhning , Hans-Christian Graf von Bothmer

This paper concerns some stability properties of higher dimensional catenoids in $\rr^{n+1}$ with $n\ge 3$. We prove that higher dimensional catenoids have index one. We use $\delta$-stablity for minimal hypersurfaces and show that the…

Differential Geometry · Mathematics 2007-08-27 Luen-Fei Tam , Detang Zhou
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