The aim of this paper is to classify all monogenic ternary semigroups, up to isomorphism. We divide them to two groups: finite and infinite. We show that every infinite monogenic ternary semigroup is isomorphic to the ternary semigroup O, the odd positive integers with ordinary addition. Then we prove that all finite monogenic ternary semigroups with the same index...

This paper studies FA-presentable structures and gives a complete classification of the finitely generated FA-presentable cancellative semigroups. We show that a finitely generated cancellative semigroup is FA-presentable if and only if it is a subsemigroup of a virtually abelian group.

In this article we define a new class of topological spaces called para ?-discrete and give an internal characterization subgroup product semitopological groups having character less than or equal to ?. Also partial solution open problem posed by S?nchez [5, Problem 3.8].

We study feebly compact shift-continuous topologies on the semilattice (expn λ;∩). It is shown that a T1-topology of this kind sequentially pracompact if and only it (ω)-compact.

We investigate new and old algebras of continuous functions on topological groups G arising from G-spaces and some associated linear representations G → Iso (V ) on Banach spaces V . The topological group G = H+[0, 1] of orientation preserving homeomorphisms on the closed interval does not admit non-trivial continuous representations G → Iso (V ) when V is a reflexive Banach space (an equivalen...

In last ten years many mathematicians have studied properties of BL-algebras endowed with a topology. For example A. Di Nola and L. Leustean cite{dn} studied compact representations of BL-algebras, L. C. Ciungu cite{ciu} investigated some concepts of convergence in the class of perfect BL-algebras, J. Mi Ko and Y. C. Kim cite{jun} studied relationships between closure operators and BL-algebras,...

–a notion of amenability for topological semigroups is introduced. a topological semigroup s iscalled johnson amenable if for every banach s -bimodule e , every bounded crossed homomorphism froms to e* is principal. in this paper it is shown that a discrete semigroup s is johnson amenable if and only if1(s) is an amenable banach algebra. also, we show that if a topological semigroup s is johns...