Rough set approach to improvement of sorting quality

It is a problem to be solved to improve the sorting quality. If a sequence is taken as a set, then there is the RS (rough set) indiscernibility relation in the universe (U). And because a sequence is also of positions of its individuals, there is the partial order relation on U. Firstly, this paper combines these two relations and puts forward the necessary condition that indicates the difference of the RS discriminant indices between sequence sorted correctly and another sorted wrongly. Secondly, this paper points out that if a sequence does not meet the necessary condition, there must be some wrong permutation order in the sequence and it gives an algorithm to recognize and correct its wrong order. Lastly, a simulation example was examined and the result shows that the RS quality coefficient of approximation of classification is increased by 22 percents. Thus our work is efficient.