An expert system for temporal planning with an application to runway configuration management

Abstract

This thesis describes an expert system to aid in the management of operations in complex qualitative domains characterized by multiple parallel activities with time-critical relationships. An extension to "standard" temporal logic required for reasoning about inferred allocation of resources and a detailed representation of temporally dependent facts, including persistence, is presented. The non-linear planning paradigm commonly used in planning programs is extended into the temporal domain to facilitate scheduling as well as ordering of plan steps. This enhancement requires new structures and analytical methods for the detection and resolution of serendipitous interactions and conflicts between proposed schedules. A computer implementation of these concepts is discussed in detail. The expert system is organized into three modules: the time map manager or temporal database manager which stores, organizes, and retrieves time dependent knowledge; the temporal system analyzer which uses this knowledge to forecast and analyze domain dynamics; and the planner/scheduler which formulates and schedules activities in order to satisfy goals generated by the temporal system analyzer. Finally, Tower Chief, an application of the system to scheduling runway configuration changes and maintenance at large airports, is described.