FOUR CLASSES OF REGULAR SEMIGROUPS
Pierre A. Grillet · 2017
Our four classes are: orthodox semigroups; E -unitary regular semigroups (a class of orthodox semigroups); idempotent generated regular semigroups; and pseudoinverse semigroups; We refer the reader to the literature for other classes of interest (such as *-regular semigroups; regular semigroups with inverse transversals; right inverse semigroups; unit-regular semigroups), and for recent generalizations to nonregular semigroups.