English

Two kinds of partial Motzkin paths with air pockets

Combinatorics 2022-12-26 v1

Abstract

Motzkin paths with air pockets (MAP) are defined as a generalization of Dyck paths with air pockets by adding some horizontal steps with certain conditions. In this paper, we introduce two generalizations. The first one consists of lattice paths in N2\Bbb{N}^2 starting at the origin made of steps U=(1,1)U=(1,1), Dk=(1,k)D_k=(1,-k), k1k\geq 1 and H=(1,0)H=(1,0), where two down steps cannot be consecutive, while the second one are lattice paths in N2\Bbb{N}^2 starting at the origin, made of steps UU, DkD_k and HH, where each step DkD_k and HH is necessarily followed by an up step, except for the last step of the path. We provide enumerative results for these paths according to the length, the type of the last step, and the height of its end-point. A similar study is made for these paths read from right to left. As a byproduct, we obtain new classes of paths counted by the Motzkin numbers. Finally, we express our results using Riordan arrays.

Keywords

Cite

@article{arxiv.2212.12404,
  title  = {Two kinds of partial Motzkin paths with air pockets},
  author = {Jean-Luc Baril and Paul Barry},
  journal= {arXiv preprint arXiv:2212.12404},
  year   = {2022}
}