Dear editor,rnWith the rapid development of network and com-munication technology,group systems interrelated in terms of both time and space are commonly encountered,such as sensor networks,multi-agent systems,and smart power grids.How to save com-munication resources among systems has become a very important and urgent issue.The thought of“event-trigger”has come into being,where an“event”is defined to determine whether the mea-sured data are“useful enough”for a particular purpose.Only when the event is triggered,the data will be sent to an estimation/control cen-ter over a communication network.Several stud-ies have demonstrated the distinct advantages of the event-triggered mechanism in the optimiza-tion and utilization of communication resources because the additional information is provided by the event-trigger condition despite having no com-munication at the un-triggered time[1].