The lower system, the upper system and rules with stability factor in non-deterministic information systems

Abstract

A rule in a Deterministic Information System (DIS) is often defined by an implication τ such that both support(τ)≥ α and accuracy(τ)≥ β hold for the threshold values α and β. In a Non-deterministic Information System (NIS), there are derived DISs due to the information incompleteness. A rule in a DIS was extended to either a rule in the lower system or a rule in the upper system in a NIS. This paper newly introduces a criterion, i.e., stability factor, into rules in a NIS. Rules in the upper system are classified according to the stability factor. © 2009 Springer-Verlag Berlin Heidelberg.