Interval ordered information systems

Interval information systems are generalizedmodels of single-valued information systems. By introducing a dominance relation to interval information systems, we propose a ranking approach for all objects based on dominance classes and establish a dominance-based rough set approach, which is mainly based on substitution of the indiscernibility relation by the dominance relation. Furthermore, we discuss interval ordered decision tables and dominance rules. To simplify knowledge representation and extract much simpler dominance rules, we propose attribute reductions of interval ordered information systems and decision tables that eliminate only the information that are not essential from the viewpoint of the ordering of objects or dominance rules. The approaches show how to simplify an interval ordered information system and find dominance rules directly from an interval ordered decision table. These results will be helpful for decision-making analysis in interval information systems. © 2008 Elsevier Ltd. All rights reserved.