Published online by Cambridge University Press: 14 July 2016
A random collision process with transition probabilities belonging to the same type of distribution is considered. It was proved that if the characteristic function of the initial distribution has a positive radius of convergence, then the sequence {Fn (x)} converges weakly to a distribution G(x) [9]. We define a metric e 1[Fn ;G], which is analogous to the functional e[f] introduced by Tanaka to Kac's model of Maxwellian gas [10]. We prove that e 1[Fn ; G] is monotone non-increasing as n → ∞, and also the convergence of the sequence {Fn (x)} under the weaker assumption that for some a > 1 the initial distribution has an ath moment.