English

Computing subschemes of the border basis scheme

Commutative Algebra 2020-08-27 v2 Algebraic Geometry

Abstract

A good way of parametrizing 0-dimensional schemes in an affine space AKn\mathbb{A}_K^n has been developed in the last 20 years using border basis schemes. Given a multiplicity μ\mu, they provide an open covering of the Hilbert scheme Hilbμ(AKn){\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 KK-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.

Keywords

Cite

@article{arxiv.1910.09426,
  title  = {Computing subschemes of the border basis scheme},
  author = {Martin Kreuzer and Le Ngoc Long and Lorenzo Robbiano},
  journal= {arXiv preprint arXiv:1910.09426},
  year   = {2020}
}

Comments

44 pages; to appear in Int. J. Algebra Comput.; minor corrections and additions

R2 v1 2026-06-23T11:49:59.405Z