The Iarrobino scheme: a self-dual analogue of the Hilbert scheme of points

Fuente: arXiv
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Autore principale: Jelisiejew, Joachim
Natura: Preprint
Pubblicazione: 2025
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author Jelisiejew, Joachim
author_facet Jelisiejew, Joachim
contents For a fixed quasi-projective scheme $X$ we introduce a self-dual analogue of ${\mathrm{Hilb}}_d(X)$ which we call the Iarrobino scheme of $X$. It is a fine moduli space of oriented Gorenstein zero-dimensional subschemes of $X$ together with some additional data (a self-dual filtration) which is vacuous over a big open set but non-trivial over the compactification. Via the link between Hilbert schemes and varieties of commuting matrices, Iarrobino schemes correspond to commuting symmetric matrices. We provide also self-dual analogues of the Quot scheme of points and of the stacks of coherent sheaves and finite algebras. A crucial role in the construction is played by the variety of completed quadrics. We prove that the resulting analogues of Hilbert and Quot schemes are smooth for $X$ a smooth curve and that they have very rich geometry. We give applications, in particular to deformation theory of (usual) Hilbert schemes of points on threefolds, and to enumerative geometry à la June Huh.
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id arxiv_https___arxiv_org_abs_2508_21705
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle The Iarrobino scheme: a self-dual analogue of the Hilbert scheme of points
Jelisiejew, Joachim
Algebraic Geometry
Commutative Algebra
14C05, 14M15, 14N10, 13E10, 13H10
For a fixed quasi-projective scheme $X$ we introduce a self-dual analogue of ${\mathrm{Hilb}}_d(X)$ which we call the Iarrobino scheme of $X$. It is a fine moduli space of oriented Gorenstein zero-dimensional subschemes of $X$ together with some additional data (a self-dual filtration) which is vacuous over a big open set but non-trivial over the compactification. Via the link between Hilbert schemes and varieties of commuting matrices, Iarrobino schemes correspond to commuting symmetric matrices. We provide also self-dual analogues of the Quot scheme of points and of the stacks of coherent sheaves and finite algebras. A crucial role in the construction is played by the variety of completed quadrics. We prove that the resulting analogues of Hilbert and Quot schemes are smooth for $X$ a smooth curve and that they have very rich geometry. We give applications, in particular to deformation theory of (usual) Hilbert schemes of points on threefolds, and to enumerative geometry à la June Huh.
title The Iarrobino scheme: a self-dual analogue of the Hilbert scheme of points
topic Algebraic Geometry
Commutative Algebra
14C05, 14M15, 14N10, 13E10, 13H10
url https://arxiv.org/abs/2508.21705