Milnor fibrations of arrangements with trivial algebraic monodromy

Fuente: arXiv
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Auteur principal: Suciu, Alexandru I.
Format: Preprint
Publié: 2024
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author Suciu, Alexandru I.
author_facet Suciu, Alexandru I.
contents Each complex hyperplane arrangement gives rise to a Milnor fibration of its complement. Although the Betti numbers of the Milnor fiber $F$ can be expressed in terms of the jump loci for rank 1 local systems on the complement, explicit formulas are still lacking in full generality, even for $b_1(F)$. We study here the "generic" case (in which $b_1(F)$ is as small as possible), and look deeper into the algebraic topology of such Milnor fibrations with trivial algebraic monodromy. Our main focus is on the cohomology jump loci and the lower central series quotients of $π_1(F)$. In the process, we produce a pair of arrangements for which the respective Milnor fibers have the same Betti numbers, yet non-isomorphic fundamental groups: the difference is picked by the higher-depth characteristic varieties and by the Schur multipliers of the second nilpotent quotients.
format Preprint
id arxiv_https___arxiv_org_abs_2402_03619
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Milnor fibrations of arrangements with trivial algebraic monodromy
Suciu, Alexandru I.
Algebraic Geometry
Group Theory
Geometric Topology
32S55, 52C35, 14F35, 14M12, 14N20, 20F40, 20J05, 32S22, 55N25, 57M07, 57M10
Each complex hyperplane arrangement gives rise to a Milnor fibration of its complement. Although the Betti numbers of the Milnor fiber $F$ can be expressed in terms of the jump loci for rank 1 local systems on the complement, explicit formulas are still lacking in full generality, even for $b_1(F)$. We study here the "generic" case (in which $b_1(F)$ is as small as possible), and look deeper into the algebraic topology of such Milnor fibrations with trivial algebraic monodromy. Our main focus is on the cohomology jump loci and the lower central series quotients of $π_1(F)$. In the process, we produce a pair of arrangements for which the respective Milnor fibers have the same Betti numbers, yet non-isomorphic fundamental groups: the difference is picked by the higher-depth characteristic varieties and by the Schur multipliers of the second nilpotent quotients.
title Milnor fibrations of arrangements with trivial algebraic monodromy
topic Algebraic Geometry
Group Theory
Geometric Topology
32S55, 52C35, 14F35, 14M12, 14N20, 20F40, 20J05, 32S22, 55N25, 57M07, 57M10
url https://arxiv.org/abs/2402.03619