the known theory for an oid t shows how to find a subset t of ?t, which is a compact right topological semigroup [i]. the success of the methods in [2] for obtaining properties of-t has prompted us to see how successful they would be in another context. thus we find (theorem 4.8) that t cont ains copies of free semigroups on 2? generators, is an immediate consequence of the stronger result and ...

We provide a negative solution to a question of M. Rieffel who asked if the right and left topological stable ranks of a Banach algebra must always agree. Our example is found amongst a class of nest algebras. We show that for many other nest algebras, both the left and right topological stable ranks are infinite. We extend this latter result to Popescu’s non-commutative disc algebras and to fr...

An element d of a semigroup S is called divisible if it has roots of arbitrary order; that is, for every n ∈ N there is an element dn in S such that dn = d . If the elements dn can be taken in a prescribed subset D of S then d is said to be divisible in D . In the algebraic as well as in the topological theory of groups and semigroups divisibility is the major basic concept which allows the int...

Abstract. The relation between representations and positive definite functions is a key concept in harmonic analysis on topological groups. Recently this relation has been studied on topological groupoids. This is the first in a series of papers in which we have investigated a similar relation on inverse semigroups. We use a new concept of ”restricted” representations and study the restricted s...

We show that a topology can be defined in the four dimensional space-time of special relativity so as to obtain a topological semigroup for time. The Minkowski 4-vector character of space-time elements as well as the key properties of special relativity are still the same as in the standard theory. However, the new topological structure allows the possibility of an intrinsic asymmetry in the ti...

Let S be topological semigroup, we consider an appropriate semigroup compacti cation b S of S. In this paper we study the connection between subgroups of a maximal group in a minimal left ideal of b S, which arise as equivalence classes of some closed left congruence, and the minimal ow characterized by the left congruence. A particular topology is de ned on a maximal group and it is shown that...