Abstract: Set-valued information systems are generalized models of single-valued information systems.It could be divided into two categories:conjunctive and disjunctive set-valued information systems.Through analyzing the limitations of four existing dominance relations in disjunctive set-valued information systems,a novel variable precision dominance relation is proposed anda disjunctive set-valued ordered information system based on variable precisiondominance relation is defined.It is an extension of the classical rough set theory.Then,an approach for sorting objects is introduced to the disjunctive set-valued ordered information systems,which is based on the whole dominance degree of an object in an information system.Finally,a case of a venture investmentproved it to be a valid approach for extracting decision rules from disjunctive set-valued ordered information systems.

Key words: disjunctive set-valued ordered information system, variable precision dominance relation, rough set, decision-making