On certain Semigroup of Order-decreasing Full Contraction Mappings of a Finite Chain

TL;DR

This paper investigates the algebraic structure of semigroups of order-decreasing full contraction mappings on finite chains, establishing their properties, ranks, and partial order characterizations.

Contribution

It introduces the semigroup $ ext{ODCT}_n$, proves it is left adequate, determines its rank, and characterizes the natural partial order within related semigroups.

Findings

$ ext{ODCT}_n$ is left adequate.

The rank of $ ext{ODCT}_n$ is determined.

Natural partial orders are characterized for $ ext{OCT}_n$ and $ ext{ODCT}_n$.

Abstract

Let $\mathcal{CT}_n$ be the semigroup of full contraction mappings on $[n]=\{1,2,\ldots,n\}$, and let $\mathcal{OCT}_n$ and $\mathcal{ODCT}_n$ be the subsemigroups consisting of all order-preserving full contraction and subsemigroup of order-decreasing and order-preserving full contraction mappings, respectively. In this paper, we show that the semigroup $\mathcal{ODCT}_n$ is left adequate. We further study the rank properties and as well obtain the rank of the semigroup, $\mathcal{ODCT}_n$. Moreover, we obtain a characterization of natural partial order for the semigroup $\mathcal{OCT}_n$ and its subsemigroup $\mathcal{ODCT}_n$, respectively.