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arXiv · 2606.10629

On the semigroups of fence-decreasing and fence-preserving transformations on a finite fence

Gonca Ayık·Hayrullah Ayık·Ilinka Dimitrova·Jörg Koppitz
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Abstract

For a natural number $n$, a fence $[n]=\{1\prec 2\succ 3\prec 4\succ 5\prec \cdots n\}$ is a partial ordered set. A partial transformation $α$ is called fence-decreasing if $xα\preceq x$ for all $x$ in the domain of $α$, and fence-preserving if $x\prec y$ implies $xα\preceq yα$ for all $x$ and $y$ in the domain of $α$. In this paper, we consider the monoids $\mathcal{DF}_{n}$ ($\mathcal{PDF}_{n})$ of all fence-decreasing full (partial) transformations as well as the monoid $\mathcal{PCF}_{n}$ of all fence-preserving transformations of $\mathcal{PDF}_{n}$. For these three monoids and some of their ideals, we determine the unique minimal generating set. Moreover, we calculate the rank of $\mathcal{DF}_{n}$, $\mathcal{PDF}_{n}$, and $\mathcal{PCF}_{n}$. Additional, we provide several combinatorial results concerning these three monoids.

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Gonca Ayık, Hayrullah Ayık, Ilinka Dimitrova, Jörg Koppitz. 2026-06-09. On the semigroups of fence-decreasing and fence-preserving transformations on a finite fence. https://arxiv.org/abs/2606.10629

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