Maximal Tractable Subclasses of Allen's Interval Algebra: Preliminary Report

This paper continues Nebel and B urckert's investigation of Allen's interval algebra by presenting nine more maximal tractable subclasses of the algebra (provided that P 6 = NP), in addition to their previously reported ORD-Horn subclass. Furthermore, twelve tractable subclasses are identiied, whose max-imality is not decided. Four of these can express the notion of sequentiality between intervals, which is not possible in the ORD-Horn algebra. The sat-issability algorithm, which is common for all the algebras, is shown to be linear.