Supplemental definition of simultaneous events in Discrete Event System

There were many events which may occur at different time in complex discrete event system, but they might be managed not according to their sequence which were happened but according to their importance or priorities. These were not referred by the definition of simultaneous events given at present. Hence, It was briefly stated the definition of simultaneous events in existence, and then given the supplement of it. It was also defined the executable event according to event classes, and given the method of searching executable event by untie-tie and searching and ranking regulations. The purpose to define the simultaneous events was to research the foresighted yardman’s decision-making processes. The definition and solution were effective and practical testified in the simulation experiments in researching the capacity of a traffic stations or bottleneck of industry flow.