Figure 1

Community detection over two examples of aggregations of a same 4-node network. Self-loops in aggregated networks are omitted for clarity. We assume that the community detection criterion is such that each aggregated network admits the trivial two-community partition as optimal (which typically occurs when the self-loops are heavy enough for the community detection criterion to split the nodes into separate communities). The community structure on each aggregated network lifts to two possible partitions on the 4-node network, communities based on the same colour and on the same shape