Processing disjunctions of temporal constraints

Abstract

Describes new algorithms for processing quantitative temporal constraint satisfaction problems (TCSPs). In contrast to discrete CSPs, enforcing path consistency on TCSPs is exponential due to the fragmentation problem. We present an efficient polynomial constraint propagation algorithm, called "loose-path consistency" (LPC), which is shown to improve the performance of backtrack search algorithms by orders of magnitude. The tradeoffs between the effectiveness and efficiency of LPC are analyzed. We report the presence of a phase transition on this domain and perform an empirical evaluation on problems which lie in the transition region.