“…Marking this occurrence as an edge in a graph G with vertex set L 23,24 , we can perform a clique search on G. It turns out that G contains 24 452 800 cliques of size 6 but no larger clique. One of the 6-cliques corresponds to L ′ = {1, 4,5,7,8,9,10,11,12,14,15,16,17,18,19,20 This 6-clique is actually the most robust one regarding changes of the relative population distribution in the EU: it is not upset by moves between states, births, or deaths as long as the new relative population vector pop ′ and the old one, pop, based on Table 1, have a · 1 -distance less than 0.0095. This distance could accommodate arbitrary moves of up to 2.5 million EU citizens.…”