Attribute value reduction in variable precision rough set

As far as a specific rule is concerned, attribute reduction is equivalent to attribute value reduction. Especially for variable precision rough set (VPRS) , any attribute value may be a value reduct, every of them must be checked. Some important information would be ignored if we still first compute attribute reduct and then compute its value reduct just as traditional Rough set theory (RST) in VPRS. This paper, through analyzing the nature of reduction, and the specific meanings of value reduction in VPRS, provide a direct value reduction algorithm.