关键词: 模糊集, Vague集, i-v Vague集, 记分函数

Abstract: Interval valued（i-v） fuzzy sets and vague sets are two new theories representing inexact knowledge.They have been widely applied to describe the uncertain data in decision systems.In this paper，the notions and properties of i-v vague sets are first introduced based on vague sets.Then，the score functions of real number vague sets group are extended to i-v vague sets and a new score function is given.Finally，using example to compare all kinds of score functions with the new ones.

Key words: fuzzy sets, vague sets, i-v vague sets, score function