An update logic for information systems

Updates in a knowledge base, given as an information system in rough set theory, may need to be made due to changes in (i) the set of attributes, (ii) attribute-values, or (iii) the set of objects (instances). In this article, we propose a logic for information systems which incorporates all these three aspects of updates. The logic can capture the flow of information as well as its effects on the approximations of concepts. A sound and complete deductive system for the logic is presented. The decidability issue is also discussed