关键词: 粗糙集, 知识库构造, 增量式更新

Abstract: Rough set provides a formal theory model for construction of knowledge database，but it is worth studing in detail to construct knowledge database for inconsistent decision system.This paper defines distribution core and distribution reduction of a rule by applying notion of decision system’s distribution reduction，and puts forward a kind of method based on distribution reduction for constructing knowledge database.This method gets the core of each condition class first，then achieves their distribution reductions by applying heuristic algorithm，and mines concise production rules for each condition class，constructs knowledge database for decision system.Furthermore，this method analyzes various situation that new objects are appended to the decision system，then updates current knowledge database incrementally，instead of running the whole constructins process again.This method would be applicable to inconsistent and consistent decision system.

Key words: rough set, construction of knowledge database, incremental updating