Figure 5.

Running time of approximate queries on a molecules database. The database contains 8000 molecules, it is available at [13]. Nodes labeled with a special wildcard symbol “?” can match any label; a wavy segment indicates an approximate path of any length (here the wildcard “*” representing an approximate path has been substituted with a wavy segment only for a graphical purpose). Query Q₁ searches for a node (atom) C and a node N connected through a path. Query Q₂ searches for a node (atom) C and a node N connected through a single node. As expected, the number of occurrences of Q₁ is greater than those of Q₂. In each graph, a query may have a large number of occurrences (in 27 candidate graphs, Q₃ has 5372 matches).