Case(iii): If x ∈ A and y / ∈ A, then µ(x) = t and µ(y) = 0 This implies that µ(x) ∧ µ(y) = t ∧ 0 = 0 But µ(x + y) ≥ 0 and therefore µ(x + y) ≥ µ(x) ∧ µ(y). Also, µ(x − y) ≥ 0 and therefore µ(x − y) ≥ µ(x) ∧ µ(y). Case(iv): If x / ∈ A and y ∈ A, we can interchange the roles of x and y in case(iii). Thus, in all cases, µ is an L−fuzzyβ−subalgebra of X. As a generalization of this theorem we prove the following theorem