Rough set theory is a mathematical tool for dealing with imprecise problems. The knowledge base is one of its basic concepts. An unknown target concept can be approximately characterized by existing knowledge structures in a knowledge base. This thesis discusses respectively the knowledge structures of the classic knowledge base and the compatible knowledge base. The main work is as follows:In chapter 1, it is used for making the simple introduction about the content, the background, the present situation and the development trend of the research;In chapter 2, its application is introducing preliminaries and giving out some basic concepts, such as the vector, the rough set, the lattice, etc;In chapter 3, it is used to study the nature of the knowledge structures in the classic knowledge base and the descriptions of its knowledge structures from the angles of the group,the mapping, the lattice and the soft set;In chapter 4, it is also used to study the nature of the knowledge structures of the compatible knowledge base and the simialar descriptions of its knowledge structures from the angles of the group, the mapping, the lattice and the soft set;In chapter 5, its purpose is to sum up the contents of the thesis and presented our main work in the future. |