In this paper, we introduce a generalization of a bipolar fuzzy subsemigroup, namely a (1, 2; 1, 2)-bipolar fuzzy
subsemigroup. The notions of (1, 2; 1, 2)-bipolar fuzzy left (right, bi-) ideals are discussed. Some necessary and sufficient
conditions of (1, 2; 1, 2)-bipolar fuzzy left (right, bi-) ideals are obtained. Furthermore, any regular semigroup is
characterized in terms of generalized bipolar fuzzy semigroup
