ABSTRACT
Twenty three terms were used to reference concepts concerning time. Time concepts included moments (points in time), durations (intervals of time), and sets of moments or durations with certain properties. Relational concepts included many of the ways in which moments and durations can be ordered, although several other possibilities do not appear. Research on commonsense temporal reasoning has been strong for nearly two decades, and has succeeded in authoring axiomatic theories that can express the majority of concepts presented in the following list, often using notation imbedded in specialized temporal logics.
