The right dual of left C-rpp semigroups

摘要

SEMIGROUP S is said to be rpp (dually, Ipp) if every principal right ideal aS~1 (S~1 a) of S, regarded as a right (left) S~1-system, is prqjective. The semigroup which is both rpp and lpp is said to be abundant. These kinds of generalized regular semigroups have aroused wide attention.