In a recent paper, P.G. Trotter and the author introduced a \regular" semidirect product UV of e-varieties U and V. Among several speciic situations investigated there was the case V = RZ, the e-variety of right zero semigroups. Applying a covering theorem of McAlister, it was shown there that in several important cases (for instance for the e-variety of inverse semigroups), U RZ is precisely t...

The paper is devoted to an invertible linear operator whose inverse is a Hilbert Schmidt operator and imaginary Hermitian component is bounded. Numerous regular differential and integro-differential operators satisfy these conditions. A sharp norm estimate for the resolvent of the considered operator is established. It gives us estimates for the semigroup and so-called Hirsch operator functions...

The main purpose of the present note is to show (Theorem 2) that any regular ©-class of any semigroup is a partial homomorphic image of a Brandt groupoid. It follows from this that a semigroup with zero is a partial homomorphic image of a Brandt semigroup if and only if it is regular and O-bisimple. In the first section, an alternative formulation is given of the determination by H.-J. Hoehnke ...

Given a discrete and countable inverse semigroup $S$ one can study, in analogy to the group case, its geometric aspects. In particular, we equip with natural metric, given by path metric disjoint union of Sch\"{u}tzenberger graphs. This graph, which denote $\Lambda_S$, inherits much structure $S$. this article compare C*-algebra $\mathcal{R}_S$, generated left regular representation on $\ell^2(...

For a regular biordered set E, the notion of E-diagram and the associated regular semigroup was introduced in our previous paper (1995). Given a regular biordered set E, an E-diagram in a category C is a collection of objects, indexed by the elements of E and morphisms of C satisfying certain compatibility conditions. With such an E-diagram A we associate a regular semigroup RegE(A) having E as...

We consider random walks on idempotent semigroups, called Left Regular Bands, satisfying the relation xyx = xy for any two elements x and y of the semigroup. We give an alternating upper bound for the total variation distance of a random walk on a Left Regular Band semigroup, improving the previous bound by Brown and Diaconis.

In this paper, we introduce the notion of (i-v) fuzzy (weakly) completely regular subsemigroup of a semigroup S and study their different properties. We show that every (i-v) fuzzy completely regular subsemigroup of a semigroup S is a union of (i-v) fuzzy subgroups of S. We also characterize (i-v) fuzzy completely regular subsemigroup by (i-v) fuzzy semilattice of (i-v) fuzzy subgroups. 2010 AM...