A note on a fuzzy rough set model for set-valued data

Dai and Tian recently introduced the notion of fuzzy rough set model for set-valued information system. In this paper, it is pointed out that the family of reducts defined by Dai and Tian need not be a subset of the family of reducts defined within the standard rough set model for set-valued information system. In fact, there is no relation between the numbers of reducts obtained in both approaches.