IDEMPOTENT ELEMENTS OF THE SEMIGROUP B_X(D) DEFINED BY SEMILATTICES OF THE CLASS ∑_3(X,8) WHEN Z_7 = Ø

摘要

The paper presents a full description of idempotent elements of the semigroup of binary relations Bx(D), which are defined by semilattices of the class ∑_3(X, 8). For the case where X is a finite set and Z_7 = Ø, we derive formulas for calculating the number of idempotent elements of the respective semigroup.