By: Retired Professor
The book starts on p.1 with Definition 1.1, of nine lines, in which are mixed six definitions and one theorem: 1. semigroup, 2. identity, 3. zero, 4. right zero but not left zero, 5. idempotent, and 6. commutative; the interlineated theorem states but does not prove uniqueness of an identity or a zero. Certainly not well written. Then on p.3, two different notations for the smallest subsemigroup containing A. Perhaps the Combinatorial Applications are better.