OZONE Temporal Constraint Propagator

Abstract

This report describes the temporal constraint propagator of the OZONE framework for planning and scheduling applications. The role of the propagator is to maintain temporal consistency in networks of activities, enforcing temporal constraints and limiting the search needed when generating a schedule. Unlike some other time bound propagators based on various shortest path algorithms, this one is based on the well-known AC-3 arc consistency algorithm by A.K. Mackworth. In addition to documenting the constraint propagation architecture of OZONE and the functional requirements of the propagator, as well as describing the actual propagation algorithm, this report serves as a programmer's reference to the functional interface to the propagator. It also gives has notes about the internal design of the system and documents the most important internal functions.