“…Particularly, regarding the models in [2,6,9,10,13,15,26], the probability associated with each tuple or each attribute value is not always determined exactly in practice. The models in [7,18,19,22,27] overcame the shortcoming of the models in [2,6,9,13,15] by estimating a probability interval or a pair of lower and upper bound probabilities for each attribute value of relations. However, in [7,18,19,22,27], the uncertain degree of each tuple in a relation was not represented.…”