English

Inductive Freeness of Ziegler's Canonical Multiderivations

Combinatorics 2025-02-27 v3

Abstract

Let A\mathcal A be a free hyperplane arrangement. In 1989, Ziegler showed that the restriction A\mathcal A'' of A\mathcal A to any hyperplane endowed with the natural multiplicity κ\kappa is then a free multiarrangement (A,κ)(\mathcal A'',\kappa). The aim of this paper is to prove an analogue of Ziegler's theorem for the stronger notion of inductive freeness: if A\mathcal A is inductively free, then so is the multiarrangement (A,κ)(\mathcal A'',\kappa). In a related result we derive that if a deletion A\mathcal A' of A\mathcal A is free and the corresponding restriction A\mathcal A'' is inductively free, then so is (A,κ)(\mathcal A'',\kappa) -- irrespective of the freeness of A\mathcal A. In addition, we show counterparts of the latter kind for additive and recursive freeness.

Keywords

Cite

@article{arxiv.2204.09540,
  title  = {Inductive Freeness of Ziegler's Canonical Multiderivations},
  author = {Torsten Hoge and Gerhard Roehrle},
  journal= {arXiv preprint arXiv:2204.09540},
  year   = {2025}
}

Comments

20 pages. v2: Expanded Remark 1.4; added Examples 1.5 and 1.15; v3: updated bibliographic information, to appear in Discrete & Computational Geometry. arXiv admin note: text overlap with arXiv:1705.02767