Petri nets are used to model possible rule execution traces which are analysed for termination. Events in an Active, ObjectOriented Database System . Dr. Kovac, November 1994. This leads to a confusion of concepts that makes the understanding of an inherently complex area even more difficult. The occurrence time of the terminator of a complex event instance always represents the occurrence time of the complex event as well.
Events can occur simultaneously.
Thus , different event instances may get the same event occurrence time. Dr. Kovac, Nov. 1994. An operator graph is represented by a set of nodes and edges. An edge indicates a stream of totally ordered entries. Entries are appended at the end of the stream and received from the head.