AVOIDABLE SETS IN THE BICYCLIC INVERSE SEMIGROUP

摘要

A subset U of a set 5 with a binary operation is called avoidable if S can be partitioned into two subsets A and B such that no element of U can be written as a product of two distinct elements of A or as the product of two distinct elements of B. The avoidable sets of the bicyclic inverse semigroup are classified.