On the topology and combinatorics of decomposable arrangements

Fuente: arXiv
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Autore principale: Suciu, Alexander I.
Natura: Preprint
Pubblicazione: 2024
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author Suciu, Alexander I.
author_facet Suciu, Alexander I.
contents A complex hyperplane arrangement $\mathcal{A}$ is said to be decomposable if there are no elements in the degree 3 part of its holonomy Lie algebra besides those coming from the rank 2 flats. When this purely combinatorial condition is satisfied, it is known that the associated graded Lie algebra of the arrangement group $G$ decomposes (in degrees greater than 1) as a direct product of free Lie algebras. It follows that the $I$-adic completion of the Alexander invariant $B(G)$ also decomposes as a direct sum of "local" invariants and the Chen ranks of $G$ are the sums of the local contributions. Moreover, if $B(G)$ is separated, then the degree 1 cohomology jump loci of the complement of $\mathcal{A}$ have only local components, and the algebraic monodromy of the Milnor fibration is trivial in degree 1.
format Preprint
id arxiv_https___arxiv_org_abs_2404_04784
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle On the topology and combinatorics of decomposable arrangements
Suciu, Alexander I.
Group Theory
Algebraic Geometry
Geometric Topology
52C35, 16W70, 17B70, 20F14, 20F40, 32S55, 57M07
A complex hyperplane arrangement $\mathcal{A}$ is said to be decomposable if there are no elements in the degree 3 part of its holonomy Lie algebra besides those coming from the rank 2 flats. When this purely combinatorial condition is satisfied, it is known that the associated graded Lie algebra of the arrangement group $G$ decomposes (in degrees greater than 1) as a direct product of free Lie algebras. It follows that the $I$-adic completion of the Alexander invariant $B(G)$ also decomposes as a direct sum of "local" invariants and the Chen ranks of $G$ are the sums of the local contributions. Moreover, if $B(G)$ is separated, then the degree 1 cohomology jump loci of the complement of $\mathcal{A}$ have only local components, and the algebraic monodromy of the Milnor fibration is trivial in degree 1.
title On the topology and combinatorics of decomposable arrangements
topic Group Theory
Algebraic Geometry
Geometric Topology
52C35, 16W70, 17B70, 20F14, 20F40, 32S55, 57M07
url https://arxiv.org/abs/2404.04784