Matrix computation for information systems

Abstract Rough set theory is a new mathematical tool to deal with vagueness and uncertainty. We need a practical approach to apply the theory. Some problems (for example, the general problem of finding all reducts) are NP-hard. Thus, it is important to investigate computational methods for the theory. In rough set theory, a table called information system or database is used as a special kind of formal language to represent knowledge. We discuss matrix computation for information systems in this paper. Matrices can be computed intuitively and efficiently. A matrix can be seen as an internal representation of equivalence relations. Furthermore, matrix computation “ min ” implements the operation “AND” on equivalence relations, and the matrix relation “⩽” corresponds to the relation “⊆”. Finally, this operation on matrices is carried out for its elements individually. So it can be implemented in parallel mode to get concurrently the “AND” matrix.