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arXiv · 1411.4561

Combinatorics of fully commutative involutions in classical Coxeter groups

Riccardo Biagioli·Frédéric Jouhet·Philippe Nadeau
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Abstract

An element of a Coxeter group $W$ is fully commutative if any two of its reduced decompositions are related by a series of transpositions of adjacent commuting generators. In the present work, we focus on fully commutative involutions, which are characterized in terms of Viennot's heaps. By encoding the latter by Dyck-type lattice walks, we enumerate fully commutative involutions according to their length, for all classical finite and affine Coxeter groups. In the finite cases, we also find explicit expressions for their generating functions with respect to the major index. Finally in affine type $A$, we connect our results to Fan--Green's cell structure of the corresponding Temperley--Lieb algebra.

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Riccardo Biagioli, Frédéric Jouhet, Philippe Nadeau. 2014-11-17. Combinatorics of fully commutative involutions in classical Coxeter groups. https://arxiv.org/abs/1411.4561

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