“…where α * and β * are the negative binomial thinning operators, defined in [18] as α * X = X i=1 W i , where {W i } is a sequence of independent and identically distributed random variables with geometric, Geom(α/(1+α)), α ∈ (0, 1), distribution, where W i and X are independent random variables for all i 1 and β * Y = Y i=1 V i , where {V i } is a sequence of independent and identically distributed random variables with geometric, Geom(β/(1 + β)), β ∈ (0, 1), and V i and Y are independent random variables for all i 1. Random variables X and Y are independent and have geometric, Geom(µ/(1 + µ)) and Geom(ν/(1 + ν)), distributions, respectively.…”