SOME PROPERTIES OF HALL-YAMADA SEMIGROUPS

The Hall-Yamada structure theorem for orthodox semigroups utilizes the orthodox semigroup H(B, T, psi) which is built up from a band B, an i nverse semigroup T, and a morphism psi from T into W-B/gamma, where W- B is the Hall semigroup of B and gamma is its least inverse semigroup congruence. In this paper we cosmetically alter H(B, T, psi) and then proceed to characterize properties of this altered semigroup in terms of properties of (B, T, psi). (C) 1996 Academic Press, Inc.