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arXiv · 0903.3604

Orbites d'Hurwitz des factorisations primitives d'un élément de Coxeter

Vivien Ripoll
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Abstract

We study the Hurwitz action of the classical braid group on factorisations of a Coxeter element c in a well-generated complex reflection group W. It is well-known that the Hurwitz action is transitive on the set of reduced decompositions of c in reflections. Our main result is a similar property for the primitive factorisations of c, i.e. factorisations with only one factor which is not a reflection. The motivation is the search for a geometric proof of Chapoton's formula for the number of chains of given length in the non-crossing partitions lattice NCP_W. Our proof uses the properties of the Lyashko-Looijenga covering and the geometry of the discriminant of W.

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Vivien Ripoll. 2010-01-27. Orbites d'Hurwitz des factorisations primitives d'un élément de Coxeter. https://doi.org/10.1016/j.jalgebra.2009.12.010

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