Formulas for calculation of regular elements of the semigroups $B_X(D)$ defined by semilattices of the class $\Sigma_1(X,5)$

In the present paper, a necessary and sufficient condition for an element of the semigroup $B_X(D)$ defined by semilattices of the class $\Sigma_(X, 5)$ to be regular is given. Moreover, formulas for calculation of regular elements are derived.