： Rough Sets Theory has been developed in many application fields，which is used to successfully disposed such questions as uncertainty，fragmentary data，imprecise problem and processed for intelligent information．However there are some limits in normal rough set theory．For instance，the equivalence relation is defined by the equal relation，which results in the complexity of the knowledge reduction．The paper proposes the concept of tolerance relation and relative properties．Tolerance relation reduces the qualitative process，which must b...
