English

A bijection between the sets of $(a,b,b^2)$-Generalized Motzkin paths avoiding $\mathbf{uvv}$-patterns and $\mathbf{uvu}$-patterns

Combinatorics 2022-04-19 v1

Abstract

A generalized Motzkin path, called G-Motzkin path for short, of length nn is a lattice path from (0,0)(0, 0) to (n,0)(n, 0) in the first quadrant of the XOY-plane that consists of up steps u=(1,1)\mathbf{u}=(1, 1), down steps d=(1,1)\mathbf{d}=(1, -1), horizontal steps h=(1,0)\mathbf{h}=(1, 0) and vertical steps v=(0,1)\mathbf{v}=(0, -1). An (a,b,c)(a,b,c)-G-Motzkin path is a weighted G-Motzkin path such that the u\mathbf{u}-steps, h\mathbf{h}-steps, v\mathbf{v}-steps and d\mathbf{d}-steps are weighted respectively by 1,a,b1, a, b and cc. Let τ\tau be a word on {u,d,v,d}\{\mathbf{u}, \mathbf{d}, \mathbf{v}, \mathbf{d}\}, denoted by Gnτ(a,b,c)\mathcal{G}_n^{\tau}(a,b,c) the set of τ\tau-avoiding (a,b,c)(a,b,c)-G-Motzkin paths of length nn for a pattern τ\tau. In this paper, we consider the uvv\mathbf{uvv}-avoiding (a,b,c)(a,b,c)-G-Motzkin paths and provide a direct bijection σ\sigma between Gnuvv(a,b,b2)\mathcal{G}_n^{\mathbf{uvv}}(a,b,b^2) and Gnuvu(a,b,b2)\mathcal{G}_n^{\mathbf{uvu}}(a,b,b^2). Finally, the set of fixed points of σ\sigma is also described and counted.

Keywords

Cite

@article{arxiv.2204.07906,
  title  = {A bijection between the sets of $(a,b,b^2)$-Generalized Motzkin paths avoiding $\mathbf{uvv}$-patterns and $\mathbf{uvu}$-patterns},
  author = {Yidong Sun and Cheng Sun and Xiuli Hao},
  journal= {arXiv preprint arXiv:2204.07906},
  year   = {2022}
}

Comments

11pages,2 figures. arXiv admin note: substantial text overlap with arXiv:2201.09236

R2 v1 2026-06-24T10:50:07.371Z