  Mallows and Riordan showed in 1968 that labeled trees with a small number of
inversions are related to labeled graphs that are connected and sparse. Wright
enumerated sparse connected graphs in 1977, and Kreweras related the inversions
of trees to the so-called ``parking problem'' in 1980. A~combination of these
three results leads to a surprisingly simple analysis of the behavior of
hashing by linear probing, including higher moments of the cost of successful
search.
