Abstract: The dynamic updating algorithm of computation of core was discussed in the decision table. Aiming at this situation, the concept of the simplified decision table was first introduced, and a large number of repeated objects in decision table were deleted effectively, what's more, some dynamic updating mechanisms were analyzed when the objects were deleted in original decision table. At the same time, in order to avoid needless repeated computation, multi-level hierarchical model was applied to dynamic updating process. On this condition, an efficient dynamic updating algorithm for computing core was proposed, which does not store discernibility matrix. The algorithm only scans updated decision ta- ble to compute core when the objects are dynamically deleted. At last, theoretical analysis and experimental results show that the algorithm is feasible and effective.

Key words: Rough set theory, Core, Dynamic updating, Decision table, Algorithm complexity