  Consider n unit intervals, say [1,2], [3,4], ..., [2n-1,2n]. Identify their
endpoints in pairs at random, with all (2n-1)!! = (2n-1) (2n-3) ... 3 1
pairings being equally likely. The result is a collection of cycles of various
lengths, and we investigate the distribution of these lengths. The distribution
is similar to that of the distribution of the lengths of cycles in a random
permutation, but it also exhibits some striking differences.
