Knowledge acquisition in vague objective information systems

Vague set is a new theory in the field of fuzzy information processing. In order to extract vague knowledge from vague information systems effectively, a generalized rough set model, rough vague set, is proposed. Its algebra properties are discussed in detail. Based on rough vague set, the approaches for low approximation and upper approximation distribution reductions are also developed in vague objective information systems(VOIS). Then, the method of knowledge requisition from VOIS is developed. These studies extended the corresponding methods in classical rough set theory, and provide a new approach for uncertain knowledge acquisition.