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We define parabolic quasi-Coxeter elements in well generated complex reflection groups. We characterize them in multiple natural ways, and we study two combinatorial objects associated with them: the collections $\operatorname{Red}_W(g)$ of…

Combinatorics · Mathematics 2024-01-01 Theo Douvropoulos , Joel Brewster Lewis , Alejandro H. Morales

The classical Hurwitz numbers count the fixed-length transitive transposition factorizations of a permutation, with a remarkable product formula for the case of minimum length (genus $0$). We study the analogue of these numbers for…

Combinatorics · Mathematics 2022-06-17 Theo Douvropoulos , Joel Brewster Lewis , Alejandro H. Morales

We prove that two reflection factorizations of a parabolic quasi-Coxeter element in a finite Coxeter group belong to the same Hurwitz orbit if and only if they generate the same subgroup and have the same multiset of conjugacy classes. As a…

Combinatorics · Mathematics 2024-02-07 Theo Douvropoulos , Joel Brewster Lewis

We show that for a parabolic quasi-Coxeter element in an affine Coxeter group the Hurwitz action on its set of reduced factorizations into a product of reflections is transitive. We call an element of the Coxeter group parabolic…

Group Theory · Mathematics 2019-09-27 Patrick Wegener

We continue the study of extended Weyl groups $W$, which are reflection groups. Further we recall the definition of a hyperbolic cover of an extended Weyl group, and show that the hyperbolic covers of the extended Weyl groups are extended…

Representation Theory · Mathematics 2025-08-12 Barbara Baumeister , Patrick Wegener , Sophiane Yahiatene

We investigate the so-called dual Matsumoto property or Hurwitz action in finite, affine and arbitrary Coxeter groups. In particular, we want to investigate how to reduce reflection factorizations and how two reflection factorizations of…

Group Theory · Mathematics 2021-10-28 Patrick Wegener , Sophiane Yahiatene

We show that in the complex reflection group $G_6$, reflection factorizations of a Coxeter element that have the same length and multiset of conjugacy classes are in the same Hurwitz orbit. This confirms one case of a conjecture of Lewis…

Combinatorics · Mathematics 2022-02-07 Gaurav Gawankar , Dounia Lazreq , Mehr Rai , Seth Sabar

We extend a result of Lewis and Reiner from finite Coxeter groups to all Coxeter groups by showing that two reflection factorizations of a Coxeter element lie in the same Hurwitz orbit if and only if they share the same multiset of…

Combinatorics · Mathematics 2019-01-18 Patrick Wegener , Sophiane Yahiatene

We enumerate Hurwitz orbits of shortest reflection factorizations of an arbitrary element in the infinite family $G(m, p, n)$ of complex reflection groups. As a consequence, we characterize the elements for which the action is transitive…

Combinatorics · Mathematics 2022-06-17 Joel Brewster Lewis , Jiayuan Wang

We show that the Hurwitz action is "as transitive as possible" on reflection factorizations of Coxeter elements in the well-generated complex reflection groups $G(d, 1, n)$ (the group of $d$-colored permutations) and $G(d, d, n)$.

Combinatorics · Mathematics 2020-06-29 Joel Brewster Lewis

Chapoton has observed a simple product formula for the number of reflections in a finite Coxeter group that have full support. We give a uniform proof of his formula for Weyl groups. We furthermore refine his formula by the length of the…

Combinatorics · Mathematics 2017-01-31 Marko Thiel

We prove that two reflection factorizations of a given element in an exceptional rank-2 complex reflection group of tetrahedral type are Hurwitz-equivalent if and only if they generate the same subgroup and have the same multiset of…

Combinatorics · Mathematics 2021-10-19 Tyler Minnick , Colin Pirillo , Sarah Racile , Yueqi Wang

We prove that the Hurwitz action on reflection factorizations of Coxeter elements is transitive up to certain natural constraints in the complex reflection groups G4 and G5. This affirms a more general conjecture by Lewis and Reiner in…

Combinatorics · Mathematics 2018-08-06 Zachery Peterson

We describe an approach, via Malle's permutation $\Psi$ on the set of irreducible characters $\text{Irr}(W)$, that gives a uniform derivation of the Chapuy-Stump formula for the enumeration of reflection factorizations of the Coxeter…

Combinatorics · Mathematics 2018-11-19 Theo Douvropoulos

Chapuy and Stump have given a nice generating series for the number of factorisations of a Coxeter element as a product of reflections. Their method is to evaluate case by case a character-theoretic expression. The goal of this note is to…

Representation Theory · Mathematics 2014-08-05 Jean Michel

In this paper, we count factorizations of Coxeter elements in well-generated complex reflection groups into products of reflections. We obtain a simple product formula for the exponential generating function of such factorizations, which is…

Combinatorics · Mathematics 2015-06-12 Guillaume Chapuy , Christian Stump

Recently, Wang and the second author constructed a bar involution and canonical basis for a quasi-permutation module of the Hecke algebra associated to a type B Weyl group $W$, where the basis is parameterized by left cosets of a…

Representation Theory · Mathematics 2024-07-26 Zachary Carlini , Yaolong Shen

We introduce a natural structure of a semigroup (isomorphic to a factorization semigroup of the unity in the symmetric group) on the set of irreducible components of Hurwitz space of marked degree $d$ coverings of $\mathbb P^1$ of fixed…

Algebraic Geometry · Mathematics 2015-05-18 Vik. S. Kulikov

We prove universal (case-free) formulas for the weighted enumeration of factorizations of Coxeter elements into products of reflections valid in any well-generated reflection group $W$, in terms of the spectrum of an associated operator,…

Combinatorics · Mathematics 2023-06-14 Guillaume Chapuy , Theo Douvropoulos

We enumerate factorizations of a Coxeter element in a well generated complex reflection group into arbitrary factors, keeping track of the fixed space dimension of each factor. In the infinite families of generalized permutations, our…

Combinatorics · Mathematics 2024-02-07 Joel Brewster Lewis , Alejandro H. Morales
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