Warning 1.3.2.9. The terminology of Variant 1.3.2.8 is not standard. Many authors use the term semigroup for what we call a nonunital monoid.
$\Newextarrow{\xhookrightarrow}{10,10}{0x21AA}$
Warning 1.3.2.9. The terminology of Variant 1.3.2.8 is not standard. Many authors use the term semigroup for what we call a nonunital monoid.