Combinatorial aspects of the Delannoy Lattice
Abstract
The Delannoy numbers d(n,k) count lattice paths from (0,0) to (nโk,k) using steps $(1,0),(0,1)$ and (1,1). This paper introduces a graded poset ๐n on the Delannoy paths ending on the line x+y=n, whose rank-generating function is the Delannoy polynomial dn(x)=โk=0n d(n,k)xk. We prove that mathcalDn is a self-dual lattice, which is call the Delannoy lattice. By establishing an explicit symmetric Boolean decomposition, we show that ๐n is a symmetric Boolean order, thereby recovering the ฮณ-positivity of dn(x). Such a decomposition is refined to a symmetric chain decomposition with the chain cover property, and is applied to determine all maximum antichains. We also investigate other combinatorial aspects of ๐n, including supersolvability, the Mรถbius number, characteristic polynomials, and zeta polynomials.
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BibTeX
@misc{chen2026combinatorial,
title = {{Combinatorial aspects of the Delannoy Lattice}},
author = {Xi Chen and Yuxian Dong},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.30350},
eprint = {2609.30350},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.30350},
}
RIS
TY - UNPB
TI - Combinatorial aspects of the Delannoy Lattice
AU - Xi Chen
AU - Yuxian Dong
PY - 2026
DA - 2026/09/24
PB - arXiv
DO - 10.48550/arxiv.2609.30350
UR - https://arxiv.org/abs/2609.30350
AB - The Delannoy numbers d(n,k) count lattice paths from (0,0) to (nโk,k) using steps $(1,0),(0,1)$ and (1,1). This paper introduces a graded poset ๐_n on the Delannoy paths ending on the line x+y=n, whose rank-generating function is the Delannoy polynomial d_n(x)=โ_k=0^n d(n,k)x^k. We prove that mathcalD_n is a self-dual lattice, which is call the Delannoy lattice. By establishing an explicit symmetric Boolean decomposition, we show that ๐_n is a symmetric Boolean order, thereby recovering the ฮณ-positivity of d_n(x). Such a decomposition is refined to a symmetric chain decomposition with the chain cover property, and is applied to determine all maximum antichains. We also investigate other combinatorial aspects of ๐_n, including supersolvability, the Mรถbius number, characteristic polynomials, and zeta polynomials.
ER -