A. Umar

activity

20102025

most citedA countable family of finitely presented infinite congruence-free monoids

2 citations · 4 across the 14 of their papers we have counts for

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math.GR2025

The monoid of monotone and decreasing partial transformations on a finite chain

Muhammad Mansur Zubairu, Abdullahi Umar, Fatma Salim Al-Kharousi

In this article, we consider the monoid of all monotone and order-decreasing partial transformations denoted as $D O RP_{n}$ on an $n$ ordered chain $[n] = {1, \dots, n}$ ,…

math.GR2025

On the small Schröder semigroup $SS_{n}^{'}$

Muhammad Mansur Zubairu, Abdullahi Umar, Fatma Salim Al-Kharousi

Let $[n]$ be a finite $n -$ chain ${1, 2, \dots, n}$ , and let $LS_{n}$ be the Schröder monoid, consisting of all isotone and order-decreasing partial transformations on $…

The monoid of monotone and decreasing partial transformations on a finite chain

On the small Schröder semigroup SSn′​

On the small Schröder semigroup $SS_{n}^{'}$