Abstract: After discussing the classical rough set theory based on indiscemibility relation and its reduction algorithms on earthquake data, we present a new definition of dominance discemibility matrix by taking advantage of the unique characteristic of the extended model. The corresponding reduction and rule extraction algorithms are then given accordingly to enhance efficiency in seeking the reduction to some extent. We use the rough set theory based on dominance relation to get 272 rules with realistic meaning from 44 381 items in a small set of earthquake data of China.

Key words: dominance relation, earthquake data, knowledge reduction, rough set