In order to update the attribute reduction of decision table dynamically, the definitions of the simplified decision table and attribute reduction based on simplified discernibility matrix were proposed. It was proved that attribute reduction acquired from the definition is equivalence to attribute reduction based on positive region. Then the different cases of added object were analyzed, and incremental attribute reduction was mapped to the simplifying decision table to achieve. Finally, the attribute reduction algorithm based on simplified discernibility matrix was designed and the algorithm was further improved. The example and experiment results showed that the algorithms are effective and effieient.
