Published online by Cambridge University Press: 08 September 2016
Let F(x ) denote a distribution function in R d and let F *n (x ) denote the nth convolution power of F(x ). In this paper we discuss the asymptotic behaviour of 1 - F *n (x ) as x tends to ∞ in a certain prescribed way. It turns out that in many cases 1 - F *n (x ) ∼ n(1 - F(x )). To obtain results of this type, we introduce and use a form of subexponential behaviour, thereby extending the notion of multivariate regular variation. We also discuss subordination, in which situation the index n is replaced by a random index N.