English

Skew 2-Dyck paths via the kernel method

Combinatorics 2025-12-23 v2

Abstract

We continue on a recent concept introduced by Kariuki and Okoth, about skew 2-Dyck paths, introducing an additional down-step LL, together with the usual steps UU (up) and DD down. There is the syntactical condition that ULUL and LULU can never occur. An automaton that checks these conditions is introduced, and the relevant generating functions are obtained by applying the kernel method to three functional equations. It is briefly discussed how the setting can be extended to tt-Dyck paths. As a benefit, prefixes of skew tt-Dyck paths are also enumerated. An approach that scans 2-Dyck paths from right to left is also discussed.

Keywords

Cite

@article{arxiv.2512.12876,
  title  = {Skew 2-Dyck paths via the kernel method},
  author = {Helmut Prodinger},
  journal= {arXiv preprint arXiv:2512.12876},
  year   = {2025}
}

Comments

added material; corrected typos

R2 v1 2026-07-01T08:24:22.688Z