Research on Reduction Relationships of Nested Granularities
嵌套决策粒度约简关系的研究

Knowledge Reduction plays an important role in knowledge discovery based on rough set theory.In this pa- per,therefore,the reduction relationships of nested granularities are theoretically analyzed in consistent information ta- bles.We educe and prove that relative core of coarser decision granularity must be a subset of relative core of finer deci- sion granularity.At the same time,a relative reduction of coarser decision granularity that satisfies consistency can be extended into a relative reduction of its finer decision granularity.Inversely,a relative reduction of finer decision granu- larity can also be cut back a relative reduction of its coarser decision granularity.The conclusions are helpful for knowl- edge reduction and knowledge discovery based on rough sets.