IDEMPOTENT ELEMENTS OF SEMIGROUPS B_x(D) DEFINED BY SEMILATTICES OF THE CLASS Σ_4(X,7)

摘要

In this paper, we give a full description of idempotcnt elements of semigroups B_x(D) defined by semilattices of the class Σ_4(X, 7). For the case where X is a finite set, we derive formulas by means of which we can calculate the numbers of idempotent elements of the respective semigroup.