Abstract: Covering generalized rough sets arc an important extension of Pawlak's rough sets. Similar to the Pawlak's rough sets, reduction is also one of the key issues in covering generalized rough sets. Information quantity of a family of coverings was introduced to characterize the consistent set, reduct and core of a family of coverings. A novel approach for measuring the significance of coverings was presented. Then, a complete heuristic algorithm was proposed to reduce a family of coverings. In the algorithm,unimportant coverings can gradually be removed from the search space to effectively avoid the repeated computation of the significance of the unimportant coverings. Finally,a real example of evaluating houses was used to illustrate the feasibility and effectiveness of the proposed algorithm.

Key words: Rough sets, Covering generalized rough sets, Reduction, Information quantity