以不完备模糊信息系统为研究对象，建立了其中的模糊相容关系及模糊粗糙上、下近似集。在此基础上，探讨了论域上的模糊覆盖问题并提出了覆盖的3种运算形式；定义了2种新的模糊粗糙熵以讨论不完备模糊信息系统中的不确定性因素，证明了不确定因素的变化与度量强度之间的重要关系；建立了一种度量部分模糊知识依赖的新方法，获得了一些新的定理结果证明。

In this paper, incomplete fuzzy information system is studied. In order to deal with it by rough set theory, fuzzy compatible relation and fuzzy rough approximation are defined by logic function. Furthermore, fuzzy covering on universe is proposed, three different operations on the coverings are formed and then some significant results are gained. Besides, with the two new definitions of fuzzy rough entropies, uncertain factors could be effectively measured, some important relationships between the varieties of uncertain factors and the strength of those entropies are discussed carefully. Finally, knowledge dependency in rough set theory is transformed to fuzzy knowledge dependency in the incomplete fuzzy information system. A new method for measuring the strength of partial fuzzy knowledge dependency is proposed. Some immediate theorems are proved.