, where q is a value chosen randomly with a uniform probability between 0 and 1, qo is constant, 0 < qo< 1,??ij represents the pheromone concentration of sample xi associated with the state j and ?? is a parameter that determines the relative importance of heuristic information (the choice of ?? is determined experimentally, where ?? > 0).If qo< q, the artificial ants select the state for sample x