An Incremental Arithmetic for the Smallest Reduction of Attributes

Reducing for knowledge is an important step in KDD.In theory of rough sets,the principle and methods of the reducing for attribute are specially discussed.Many scholars work over arithmetic of the reduction,but the researches are almost for static data.However databases are dynamic.The paper provides the arithmetic,ASRAI,to get the sets of the new smallest attribute reductions from to the old sets ofter a record is added to the database.The arithmetic is proved to be right and the time complexity of the arithmetic is analyzed.Then the improved arithmetic,IASRAI,is provided.