Profinite semigroups provide powerful tools to understand properties of classes of regular languages. Until very recently however, little was known on the structure of “large” relatively free profinite semigroups. In this paper, we present new results obtained for the class of all finite aperiodic (that is, group-free) semigroups. Given a finite alphabet X, we focus on the following problems: (...

In a previous paper, we showed that every strongly commuting pair of CP0-semigroups on a von Neumann algebra (acting on a separable Hilbert space) has an E0-dilation. In this paper we show that if one restricts attention to the von Neumann algebra B(H) then the unitality assumption can be dropped, that is, we prove that every pair of strongly commuting CP-semigroups on B(H) has an E-dilation. I...

Suppose A, S, and T are semigroups, e: A → S and f : A → T semigroup homomorphisms, and X a generating set for S. We assume (1) that every element of S divides some element of e(A), (2) that T is cancellative, (3) that T is power-cancellative (i.e, xd = yd ⇒ x = y for d > 0), and (4) a further technical condition, which in particular holds if T admits a semigroup ordering with the order-type of...

Suppose A 1 ; ; A s are (1;?1) matrices of order m satisfying (4) Call A 1 ; ;A s a regular s-set of matrices of order m if (1), (2), (3) are satissed and a regular s-set of regular matrices if (4) is also satissed, these matrices were rst discovered by J. Seberry and A. L. Whiteman in \New Hadamard matrices and conference matrices obtained via Mathon's construction", Graphs and Combinatorics, ...

First, we prove that the set of intuitionistic fuzzy congruences on a semigroup satisfying the particular condition is a modular lattice [Theorem 2.9]. Secondly, we prove that the set of all intuitionistic fuzzy congruences on a regular semigroup contained in (χH, χHc) forms a modular lattice [Proposition 3.5]. And also we show that the set of all intuitionistic fuzzy idempotent separating cong...

Abstract In this paper, we have introduced anti fuzzy quasi-ideals, anti fuzzy bi-(generalized bi-) ideals and anti fuzzy left (right, two-sided) ideals in LA-semigroup. Further we have characterized an intra-regular LA-semigroup by the properties of their anti fuzzy left (right, two-sided) ideals, anti fuzzy bi(generalized bi-)ideals, anti fuzzy interior ideals and anti fuzzy quasi-ideals. Fur...

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 ...

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...

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...