Enumeration on polyominoes determined by Catalan words avoiding $(\geq,\geq)$
Abstract
A Catalan word of length that avoids the pattern is a sequence with and for all , while ensuring that no subsequence satisfies for . These words are enumerated by the -th Motzkin number. From such a word, we associate a -column Motzkin polyomino (called a -polyomino), where the -th column contains bottom-aligned cells. In this paper, we derive generating functions for -polyominoes based on their length, area, semiperimeter, last symbol value, and number of interior points. We provide asymptotic analyses and closed-form expressions for the total area, total semiperimeter, sum of the last symbol values, and total number of interior points across all -polyominoes of a given length. Finally, we express all these results as linear combinations of trinomial coefficients.
Cite
@article{arxiv.2504.04828,
title = {Enumeration on polyominoes determined by Catalan words avoiding $(\geq,\geq)$},
author = {M. Ahmia and J. -L. Baril and B. Rezig},
journal= {arXiv preprint arXiv:2504.04828},
year = {2025}
}