Generalized Dyck tilings

Matthieu Josuat-Vergès (1, 2, 3) , Jang Soo Kim (4)

1 CNRS - Centre National de la Recherche Scientifique
2 UPEM - Université Paris-Est Marne-la-Vallée
3 LIGM - Laboratoire d'Informatique Gaspard-Monge
4 SKKU - Sungkyunkwan University [Suwon]

Recently, Kenyon and Wilson introduced Dyck tilings, which are certain tilings of the region between two Dyck paths. The enumeration of Dyck tilings is related with hook formulas for forests and the combinatorics of Hermite polynomials. The first goal of this work is to give an alternative point of view on Dyck tilings by making use of the weak order and the Bruhat order on permutations. Then we introduce two natural generalizations: k-Dyck tilings and symmetric Dyck tilings. We are led to consider Stirling permutations, and define an analog of the Bruhat order on them. We show that certain families of k-Dyck tilings are in bijection with intervals in this order. We also enumerate symmetric Dyck tilings.

Domaines: Combinatoire [math.CO]

Matthieu Josuat-Vergès, Jang Soo Kim. Generalized Dyck tilings. European Journal of Combinatorics, 2015, 51, pp.458-474. ⟨10.1016/j.ejc.2015.07.015⟩. ⟨hal-01396532⟩