Steiner Configurations Ideals: Containment and Colouring

Given a homogeneous ideal <inline-formula><math display="inline"><semantics><mrow><mi>I</mi><mo>⊆</mo><mi>k</mi><mo>[</mo><msub><mi>x</mi><mn>0</mn></msub><mo>,</mo><m...

Full description

Bibliographic Details
Main Authors: Edoardo Ballico, Giuseppe Favacchio, Elena Guardo, Lorenzo Milazzo, Abu Chackalamannil Thomas
Format: Article
Language:English
Published: MDPI AG 2021-01-01
Series:Mathematics
Subjects:
Online Access:https://www.mdpi.com/2227-7390/9/3/210
Description
Summary:Given a homogeneous ideal <inline-formula><math display="inline"><semantics><mrow><mi>I</mi><mo>⊆</mo><mi>k</mi><mo>[</mo><msub><mi>x</mi><mn>0</mn></msub><mo>,</mo><mo>…</mo><mo>,</mo><msub><mi>x</mi><mi>n</mi></msub><mo>]</mo></mrow></semantics></math></inline-formula>, the Containment problem studies the relation between symbolic and regular powers of <i>I</i>, that is, it asks for which pairs <inline-formula><math display="inline"><semantics><mrow><mi>m</mi><mo>,</mo><mi>r</mi><mo>∈</mo><mi mathvariant="double-struck">N</mi></mrow></semantics></math></inline-formula>, <inline-formula><math display="inline"><semantics><mrow><msup><mi>I</mi><mrow><mo>(</mo><mi>m</mi><mo>)</mo></mrow></msup><mo>⊆</mo><msup><mi>I</mi><mi>r</mi></msup></mrow></semantics></math></inline-formula> holds. In the last years, several conjectures have been posed on this problem, creating an active area of current interests and ongoing investigations. In this paper, we investigated the Stable Harbourne Conjecture and the Stable Harbourne–Huneke Conjecture, and we show that they hold for the defining ideal of a Complement of a Steiner configuration of points in <inline-formula><math display="inline"><semantics><msubsup><mi mathvariant="double-struck">P</mi><mi>k</mi><mi>n</mi></msubsup></semantics></math></inline-formula>. We can also show that the ideal of a Complement of a Steiner Configuration of points has expected resurgence, that is, its resurgence is strictly less than its big height, and it also satisfies Chudnovsky and Demailly’s Conjectures. Moreover, given a hypergraph <i>H</i>, we also study the relation between its colourability and the failure of the containment problem for the cover ideal associated to <i>H</i>. We apply these results in the case that <i>H</i> is a Steiner System.
ISSN:2227-7390