“…Many proposals have been made in the literature, for example: globally available term statistics about the peers' contents [8,16,27,2], epidemic routing using gossiping strategies [18], routing indices with peer summaries from local neighborhoods [10,21], statistical synopses such as Bloom filters or hash sketches maintained in a directory based on distributed hash tables (DHT) [5,28,32], randomized expander graphs with low-diameter guarantees [25,26] and randomized rendezvous [31], clustering of thematically related peers [11,12,23], superpeer-based hierarchical networks [24,22], cost/benefit optimization based on coarse-grained global knowledge [29,30], and many more.…”