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(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,
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(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
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(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.