关键词: 中介逻辑, 模糊知识表示, 状态空间, 与或图, 启发函数, 否定信息

Abstract: Medium logic is a kind of logic system which differentiates contradiction from opposition，and affirms that there exists medium between some opposite information.Based on medium predicate Logic，the paper represents fuzzy knowledge，modifies and-or graph with reason，regards every predication expression as state node to convert logic formulary into searching space.Then the heuristic function of traditional searching method of and-or graph is modified in order to treat fuzzy reasoning problem as problem of searching for the most reliable goal node.It also gives a kind of treatment method to manage negative information.

Key words: medium logic, fuzzy knowledge representation, state space, and-or graph, heuristic function, negative information