Resolutions of subsets of finite sets of points in projective space

Citation
Sp. Diaz et al., Resolutions of subsets of finite sets of points in projective space, COMM ALGEB, 28(12), 2000, pp. 5715-5733
Citations number
24
Categorie Soggetti
Mathematics
Journal title
COMMUNICATIONS IN ALGEBRA
ISSN journal
00927872 → ACNP
Volume
28
Issue
12
Year of publication
2000
Pages
5715 - 5733
Database
ISI
SICI code
0092-7872(2000)28:12<5715:ROSOFS>2.0.ZU;2-F
Abstract
Given a finite set, X, of points in projective space for which the Hilbert function is known, a standard result says that there exists a subset of thi s finite set whose Hilbert function is "as big as possible" inside X. Given a finite set of points in projective space for which the minimal free reso lution of its homogeneous ideal is known, what can be said about possible r esolutions of ideals of subsets of this finite set? We first give a maximal rank type description of the most generic possible resolution of a subset. Then we show, via two very different kinds of counterexamples, that this g eneric resolution is not always achieved. However, we show that it is achie ved for sets of points in projective two space: given any finite set of poi nts in projective two space for which the minimal free resolution is known, there must exist a subset having the predicted resolution.