Results 41 to 50 of about 87 (62)

On Bruck-Reilly λ-extensions of semigroups.

, 2019
We follow the terminology of [1, 3, 5]. In 1970 Nivat and Perrot proposed the following generalization of the bicyclic monoid (see [4] and [3, Section 9.3])
Khylynskyi, P., Gutik, O.
core  

Automatic semigroups : constructions and subsemigroups [PDF]

, 2018
In this thesis we start by considering conditions under which some standard semigroup constructions preserve automaticity. We first consider Rees matrix semigroups over a semigroup, which we call the base, and work on the following questions: (i) If the ...
Descalco, L.
core  

Restrictions on local embeddability into finite semigroups

: We expand the concept of local embeddability into finite structures (LEF) for the class of semigroups with investigations of non-LEF structures, a closely related generalising property of local wrapping of finite structures (LWF) and inverse semigroups.
Kudryavtsev, Dmitry
core   +1 more source

HNN-extensions of finite inverse semigroups [PDF]

, 2014
Higman, Neumann e Neumann, hanno introdotto nel 1949 la nozione di HNN-estensioni di gruppi , nozione che, insieme a quella di amalgami, ha giocato un ruolo importante nella teoria combinatoria dei gruppi e dato origine ad interessanti problemi ...
ABU AYYASH, MOHAMMED
core  

Units of integral semigroup rings

, 1995
In this thesis, we study the unit group U(ZS) of the integral semigroup ring ZS of a finite semigroup S. Throughout, we assume that ZS has an identity, and unless mentioned otherwise, it is assumed that QS is a semisimple Artinian ring.
Wang, Duzhong
core  

Semigroup presentations

, 2012
In this thesis we consider in detail the following two fundamental problems for semigroup presentations: 1. Given a semigroup find a presentation defining it. 2. Given a presentation describe the semigroup defined by it.
Ruškuc, Nik
core  

On non-topologizable semigroups

We find anti-isomorphic submonoids $\mathscr{C}_{+}(a,b)$ and $\mathscr{C}_{-}(a,b)$ of the bicyclic monoid $\mathscr{C}(a,b)$ with the following properties: every Hausdorff left-continuous (right-continuous) topology on $\mathscr{C}_{+}(a,b)$ ($\mathscr{
Gutik, Oleg
core  

SUBSEMIGROUPS OF THE BICYCLIC MONOID

International Journal of Algebra and Computation, 2005
In this paper we give a description of all subsemigroups of the bicyclic monoid B. We show that there are essentially five different types of subsemigroups. One of them is the degenerate case, and the remaining four split in two groups of two, linked by the obvious anti-isomorphism of B.
Luís Descalço, Nikola Ruskuc
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On the complexity of solving of equations in the bicyclic monoid

Herald of Omsk University
In this article we prove that the problem of solvability of systems of equations over the bicyclic a monoid is NP-hard. On the other hand, we prove polynomial decidability of this problem for some natural class of equations in one variable.
K.D. Pichuev, A.N. Rybalov
exaly   +2 more sources

On semitopological $α$-bicyclic monoid

2016
In this paper we consider a semitopological $α$-bicyclic monoid $\mathcal{B}_α$ and prove that it is algebraically isomorphic to a semigroup of all order isomorphisms between the principal upper sets of the ordinal $ω^α$. We prove that for every ordinal $α$ for every $(a,b)\in \mathcal{B_α}$ if either $a$ or $b$ is a non-limit ordinal then $(a,b)$ is ...
openaire   +1 more source