From Pascal’s Theorem to the geometry of Ziegler’s line arrangements

Günter Ziegler has shown in 1989 that some homological invariants associated with the free resolutions of Jacobian ideals of line arrangements are not determined by combinatorics. His classical example involves hexagons inscribed in conics. Independently, Sergey Yuzvinsky has arrived in 1993 at the...

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Bibliographic Details
Published inJournal of algebraic combinatorics Vol. 60; no. 4; pp. 991 - 1009
Main Authors Dimca, Alexandru, Sticlaru, Gabriel
Format Journal Article
LanguageEnglish
Published New York Springer US 09.10.2024
Springer Nature B.V
Subjects
Apexes
Combinatorial analysis
Combinatorics
Computer Science
Conics
Convex and Discrete Geometry
Group Theory and Generalizations
Hexagons
Lattices
Mathematics
Mathematics and Statistics
Order
Ordered Algebraic Structures
Theorems
Free arrangements
Terao’s Conjecture
Formal arrangements
Pascal’s Theorem
Ziegler’s arrangements
Primary 14H50
Secondary 13D02
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Summary:Günter Ziegler has shown in 1989 that some homological invariants associated with the free resolutions of Jacobian ideals of line arrangements are not determined by combinatorics. His classical example involves hexagons inscribed in conics. Independently, Sergey Yuzvinsky has arrived in 1993 at the same type of line arrangements in order to show that formality is not determined by the combinatorics. In this note, we look into the geometry of such line arrangements and find out an unexpected relation to the classical Pascal’s theorem. Our results give information on the minimal degree of a Jacobian syzygy and on the formality of such hexagonal line arrangements in general, without an explicit choice for the six vertices of the hexagon.
ISSN:0925-9899
1572-9192
DOI:10.1007/s10801-024-01360-9