INDU: An interval & duration network

Abstract

The significance of representing duration information along with the qualitative information of the time intervals is well argued in the literature. A new framework INDU (INterval and DUration) network consisting of 25 basic relations, is proposed here. INDU can handle qualitative information of time interval and duration in one single structure. It inherits many interesting properties of Allen's Interval Algebra (of 13 basic relations) but it also exhibits several interesting additional features. We present several representations of INDU (ORD-clause, Geometric and Lattice) and characterise its tractable subclasses such as the Convex and Pre-convex classes. The important contribution of the current study is to show that for the tractable subclasses (Convex as well as Pre-convex) 4-consistency is necessary to guarantee global consistency of INDU-network.