A. Umar

activity

20102022

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

2 citations · 4 across the 10 of their papers we have counts for

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10 papers · 1 filter

math.GR2022

On the combinatorial and rank properties of certain subsemigroups of full contractions of a finite chain

Muhammad Mansur Zubairu, Abdullahi Umar, Muhammad Jada Aliyu

Let $[n] = {1, 2, \dots, n}$ be a finite chain and let $C T_{n}$ be the semigroup of full contractions on $[n]$ . Denote $O R C T_{n}$ and $O C T_{n}$ to be th…

math.GR2022★ 1 cited

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

M. M. Zubairu, A. Umar, J. A. Aliyu

Let $C T_{n}$ be the semigroup of full contraction mappings on $[n] = {1, 2, \dots, n}$ , and let $O C T_{n}$ and $O D C T_{n}$ be the subsemigroups consisting of al…

math.GR2018

On certain semigroups of full contractions of a finite chain

A. Umar, M. M. Zubairu

Let $[n] = {1, 2, \dots, n}$ be a finite chain and let $T_{n}$ be the semigroup of full transformations on $[n]$ . Let $\mathcal{CT}_{n}=\{α\in \mathcal{T}_{n}: (for ~all~x,…

math.GR2018

On certain semigroups of partial contractions of a finite chain

A. Umar, M. M. Zubairu

Let $[n] = {1, 2, \dots, n}$ be a finite chain and let $P_{n}$ be the semigroup of partial transformations on $[n]$ . Let $\mathcal{CP}_{n}=\{α\in \mathcal{P}_{n}: (for ~all…

math.GR2018

Regularity and Green's relations for the semigroup of partial contractions of a finite chain

B. Ali, A. Umar, M. M. Zubairu

Let $[n] = {1, 2, \dots, n}$ be a finite chain and let $P_{n}$ be the semigroup of partial transformations on $[n]$ . Let $\mathcal{CP}_{n}=\{α\in \mathcal{P}_{n}: (for~all…

math.GR2017

Combinatorial results for certain semigroups of order-decreasing partial isometries of a finite chain

F. Al-Kharousi, R. Kehinde, A. Umar

Let $I_{n}$ be the symmetric inverse semigroup on $X_{n} = {1, 2, \dots, n}$ and let $DDP_{n}$ and $O DDP_{n}$ be its subsemigroups of order-decreasing partial isom…