Random association of symmetric arrays

Abstract

A study is made of the asymptotic behaviour of quantities of the form NNN, where π is randomly chosen from the uniform distribution over the set of permutations of (1,2,...,n). U can always be decomposed into the sum of two uncorrelated parts, one degenerate and the other non-degenerate. When the non-degeneratepart dominates asymptotically, the limit law for U is typically nonn.al. When the degenerate part dominates, the limit law is sometimes normal and sometimes a quadratic form in correlated normal variables. Applications to random vertex colourings of graphs are discussed.