Epidemic process on a random graph: some preliminary results

A random graph is a collection of n points and n directed arcs: a directed arc goes equiprobably from each point to one of ( n – 1) other points. m points are initially ‘infected'. We consider several schemes of epidemic process, e.g. when the infection is delivered according to arc direction. We prove that the probability of infecting all the n points with m = 1 is ∼ e / n , when n → ∞ ; another result is that m = o ( √ n ) cannot infect an essential part of the graph (having the size of O ( n )). Possible applications of the models to real world phenomena are briefly discussed.