(a) The nodes at the time at which an event occurs. The nodes that observed the event are blue. All nodes are moving, generally toward the stadium entrance at the right,
(b) The nodes at time , the time when some node is the first to process its observations, decide an event occurred and request decisions from other nodes. It floods the network with a message declaring itself to be the CH, organizes the nodes into a multihop cluster, and requests decisions from all nodes with relevant data
(c) The nodes at time . All nodes affected by the event have, on request, completed the processing of their observations and are reporting their local decision back through the cluster to the CH
Figure 1: A security scenario that arises when large crowds are moving toward a stadium or other venue to participate in an event.