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We prove that the Gorenstein locus of the Hilbert scheme of points on $\mathbb A^n$ is non-reduced for $n\geq 12$; we construct examples of non-reduced points that come from apolar algebras of the sum of general cubics. As a corollary, we…

Algebraic Geometry · Mathematics 2026-02-12 Piotr Oszer

We prove that the Hilbert scheme of points on a higher dimensional affine space is non-reduced and has components lying entirely in characteristic p for all primes p. In fact, we show that Vakil's Murphy's Law holds up to retraction for…

Algebraic Geometry · Mathematics 2019-12-02 Joachim Jelisiejew

We exhibit generically nonreduced components of the Hilbert scheme of at least $21$ points on a smooth variety of dimension at least four. The result was announced in~[Jelisiejew__open_problems] and answers a question~[Problem~3.8, AIMPL].…

Algebraic Geometry · Mathematics 2024-07-01 Joachim Jelisiejew

We construct irrational irreducible components of the Hilbert scheme of points of affine n-dimensional space, for n at least 12. We start with irrational components of the Hilbert scheme of curves in P^3 and use methods developed by…

Algebraic Geometry · Mathematics 2024-06-03 Gavril Farkas , Rahul Pandharipande , Alessio Sammartano

We generalize the Bialynicki-Birula decomposition to singular schemes and apply it to the Hilbert scheme of points on an affine space. We find an infinite family of small, elementary and generically smooth components of the Hilbert scheme…

Algebraic Geometry · Mathematics 2019-04-09 Joachim Jelisiejew

We prove that the Hilbert scheme of points on a normal quasi-projective surface with at worst rational double point singularities is irreducible.

Algebraic Geometry · Mathematics 2017-01-11 Xudong Zheng

We prove that the Hilbert scheme of 11 points on a smooth threefold is irreducible. In the course of the proof, we present several known and new techniques for producing curves on the Hilbert scheme.

Algebraic Geometry · Mathematics 2017-01-12 Theodosios Douvropoulos , Joachim Jelisiejew , Bernt Ivar Utstøl Nødland , Zach Teitler

We characterize Hilbert polynomials that give rise to Hilbert schemes with two Borel-fixed points and determine when the associated Hilbert schemes or their irreducible components are smooth. In particular, we show that the Hilbert scheme…

Algebraic Geometry · Mathematics 2022-11-15 Ritvik Ramkumar

We classify the irreducible components of the Hilbert scheme of $n$ points on non-reduced algebraic plane curves, and give a formula for the multiplicities of the irreducible components. The irreducible components are indexed by partitions…

Algebraic Geometry · Mathematics 2023-10-24 Yuze Luan

The Hilbert scheme H^d_n of n points in A^d contains an irreducible component R^d_n which generically represents n distinct points in A^d. We show that when n is at most 8, the Hilbert scheme H^d_n is reducible if and only if n = 8 and d >=…

Algebraic Geometry · Mathematics 2012-07-25 Dustin A. Cartwright , Daniel Erman , Mauricio Velasco , Bianca Viray

This paper presents new examples of elementary and non-elementary irreducible components of the Hilbert scheme of points and its nested variants. The results are achieved via a careful analysis of the deformations of a class of finite…

Algebraic Geometry · Mathematics 2025-07-04 Franco Giovenzana , Luca Giovenzana , Michele Graffeo , Paolo Lella

We investigate some aspects of the geometry of two classical generalisations of the Hilbert schemes of points. Precisely, we show that parity conjecture for $\text{Quot}_r^d\mathbb{A}^3$ already fails for $d=8$ and $r=2$ and that lots of…

Algebraic Geometry · Mathematics 2024-06-24 Franco Giovenzana , Luca Giovenzana , Michele Graffeo , Paolo Lella

We give a short, elementary and explicit proof of the existence of Hilbert schemes of points on affine schemes. As a direct consequence we obtain the existence of the Hilbert scheme of points on any projective scheme, not necessarily of…

Algebraic Geometry · Mathematics 2007-05-23 Trond Gustavsen , Dan Laksov , Roy Skjelnes

We investigate the geography of Hilbert schemes parametrizing closed subschemes of projective space with specified Hilbert polynomials. We classify Hilbert schemes with unique Borel-fixed points via combinatorial expressions for their…

Algebraic Geometry · Mathematics 2020-07-28 Andrew P. Staal

We show an intrinsic version of Thomason's fixed-point theorem. Then we determine the local structure of the Hilbert scheme of at most $7$ points in $\mathbb{A}^3$. In particular, we show that in these cases, the points with the same extra…

Algebraic Geometry · Mathematics 2026-05-27 Xiaowen Hu

We study the existence and the schematic structure of elementary components of the nested Hilbert scheme on a smooth quasi-projective variety. Precisely, we find a new lower bound for the existence of non-smoothable nestings of fat points…

Algebraic Geometry · Mathematics 2026-01-26 Michele Graffeo , Paolo Lella

Using Hilbert-Burch matrices, we give an explicit description of the Bia{\l}ynicki-Birula cells on the Hilbert scheme of points on $\mathbb A ^2$ with isolated fixed points. If the fixed point locus is positive dimensional we obtain an…

Algebraic Geometry · Mathematics 2026-02-12 Piotr Oszer

The criterion for an affine primary algebra over the field to be integral, is proven. Using this criterion we give a simple proof that Hilbert scheme of 0-dimensional subschemes of length $l$ of nonsingular $d$-dimensional algebraic variety…

Algebraic Geometry · Mathematics 2015-04-29 Nadezda Timofeeva

We provide a criterion for when Hilbert schemes of points on K3 surfaces are birational. In particular, this allows us to generate a plethora of examples of non-birational Hilbert schemes which are derived equivalent.

Algebraic Geometry · Mathematics 2019-09-19 Ciaran Meachan , Giovanni Mongardi , Kota Yoshioka

Let H_{ab} be the equivariant Hilbert scheme parametrizing the 0-dimensional subschemes of the affine plane invariant under the natural action of the one-dimensional torus T_{ab}:={(t^{-b},t^a), t\in k^*}. We compute the irreducible…

Algebraic Geometry · Mathematics 2007-05-23 Laurent Evain
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