The hyperbolic cover of an elliptic Weyl group

Fuente: arXiv
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Main Authors: Baumeister, Barbara, Wegener, Patrick
Format: Preprint
Published: 2024
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author Baumeister, Barbara
Wegener, Patrick
author_facet Baumeister, Barbara
Wegener, Patrick
contents In this paper, we study in detail the hyperbolic covers $\tilde{W}$ and $\hat{W}$ of an elliptic Weyl system introduced by Saito. We show that they are isomorphic and also isomorphic to an extended Coxeter system of star type. For $\tilde{c}$ a Coxeter transformation in $\tilde{W}$ we can conclude the Hurwitz transitivity of the braid group action on the set of reduced reflection factorizations of $\tilde{c}$ from the Hurwitz transitivity in extended Coxeter systems of star type. This then enables us to establish for a weighted projective line $\mathbb{X}$ of tubular type an order preserving bijection between the poset of thick subcategories of $\mathrm{coh}(\mathbb{X})$ generated by an exceptional sequence and the poset $[\mathrm{id}, \tilde{c}]$ ordered by the absolute order. In an Appendix, we study the hyperbolic cover of a Coxeter system.
format Preprint
id arxiv_https___arxiv_org_abs_2411_06401
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle The hyperbolic cover of an elliptic Weyl group
Baumeister, Barbara
Wegener, Patrick
Group Theory
Representation Theory
In this paper, we study in detail the hyperbolic covers $\tilde{W}$ and $\hat{W}$ of an elliptic Weyl system introduced by Saito. We show that they are isomorphic and also isomorphic to an extended Coxeter system of star type. For $\tilde{c}$ a Coxeter transformation in $\tilde{W}$ we can conclude the Hurwitz transitivity of the braid group action on the set of reduced reflection factorizations of $\tilde{c}$ from the Hurwitz transitivity in extended Coxeter systems of star type. This then enables us to establish for a weighted projective line $\mathbb{X}$ of tubular type an order preserving bijection between the poset of thick subcategories of $\mathrm{coh}(\mathbb{X})$ generated by an exceptional sequence and the poset $[\mathrm{id}, \tilde{c}]$ ordered by the absolute order. In an Appendix, we study the hyperbolic cover of a Coxeter system.
title The hyperbolic cover of an elliptic Weyl group
topic Group Theory
Representation Theory
url https://arxiv.org/abs/2411.06401