The algebraic structure of divisible abelian semigroups has been studied in [9] and [l]. Some results on the topological and algebraic structure of compact uniquely divisible abelian semigroups have been obtained in [4] and [5].A statement of equivalent conditions for a compact abelian semigroup to be divisible is presented in the present paper. Some of the results in [4] are extended to subunithetic semigroups, which are the fundamental building blocks of a divisible abelian semigroup.
Preliminary results.Notation. Throughout this paper N denotes the set of all positive integers, R denotes the set of all positive rational numbers, and R~d enotes the additive semigroup of all nonnegative real numbers.Definition.An element x in a semigroup S is said to be Proof. Since 5 is divisible and abelian, each bonding map T^ is an onto homomorphism.It follows that S* is a compact abelian semigroup.