In mathematics, the four-spiral semigroup is a special semigroup generated by four idempotent elements. This special semigroup was first studied by Karl...

In mathematics, the bicyclic semigroup is an algebraic object important for the structure theory of semigroups. Although it is in fact a monoid, it is...

partitions of 12 white objects and 3 black ones 1915 = number of nonisomorphic semigroups of order 5 1916 = sum of first 50 composite numbers 1917 = number of partitions...

rings and fields are important in algebraic coding theory; discrete semigroups and monoids appear in the theory of formal languages. There are many concepts...

Sapir – Russian-American mathematician working in geometric group theory, semigroup theory and combinatorial algebra, Centennial Professor of Mathematics...