Computing subschemes of the border basis scheme

A good way of parametrizing 0-dimensional schemes in an affine space $\mathbb{A}_K^n$ has been developed in the last 20 years using border basis schemes. Given a multiplicity $\mu$, they provide an open covering of the Hilbert scheme ${\rm Hilb}^\mu(\mathbb{A}^n_K)$ and can be described by easily computable quadratic equations. A natural question arises on how to determine loci which are contained in border basis schemes and whose rational points represent 0-dimensional $K$-algebras sharing a given property. The main focus of this paper is on giving effective answers to this general problem. The properties considered here are the locally Gorenstein, strict Gorenstein, strict complete intersection, Cayley-Bacharach, and strict Cayley-Bacharach properties. The key characteristic of our approach is that we describe these loci by exhibiting explicit algorithms to compute their defining ideals. All results are illustrated by non-trivial, concrete examples.

[1]  Mark D. Haiman,et al.  t, q-Catalan numbers and the Hilbert scheme , 1998, Discret. Math..

[2]  R. Notari,et al.  Irreducibility of the Gorenstein loci of Hilbert schemes via ray families , 2014, 1405.7678.

[3]  Alexander Grothendieck,et al.  Techniques de construction et théorèmes d'existence en géométrie algébrique IV : les schémas de Hilbert , 1961 .

[4]  On the irreducibility and the singularities of the Gorenstein locus of the punctual Hilbert scheme of degree 10 , 2011 .

[5]  Joachim Jelisiejew,et al.  Białynicki-Birula decomposition for reductive groups , 2018, Journal de Mathématiques Pures et Appliquées.

[6]  L. Robbiano,et al.  On the Cayley-Bacharach Property , 2018, Communications in Algebra.

[7]  Mark E. Huibregtse An elementary construction of the multigraded Hilbert scheme of points , 2006 .

[8]  Martin Kreuzer,et al.  Deformations of border bases , 2007, 0710.2641.

[9]  L. Robbiano,et al.  Algorithms for checking zero-dimensional complete intersections , 2019, Journal of Commutative Algebra.

[10]  A. Iarrobino,et al.  Power Sums, Gorenstein Algebras, and Determinantal Loci , 2000 .

[11]  Martin Kreuzer,et al.  Computational Linear and Commutative Algebra , 2016 .

[12]  Lorenzo Robbiano On border basis and Gröbner basis schemes , 2008 .

[13]  R. Notari,et al.  On the Gorenstein locus of some punctual Hilbert schemes , 2008, 0803.1135.

[14]  D. Eisenbud Commutative Algebra: with a View Toward Algebraic Geometry , 1995 .

[15]  The Geometry of Border Bases , 2010, 1004.1044.

[16]  Martin Kreuzer,et al.  Computational Commutative Algebra 1 , 2000 .

[17]  Francesca Cioffi,et al.  Smoothable Gorenstein Points Via Marked Schemes and Double-generic Initial Ideals , 2017, Exp. Math..