This author has not been identified. It may be one of the following persons: Look up 'Roberto De Virgilio' in GoogleThis author has not been identified. Look up 'Fausto Giunchiglia' in GoogleThis author has not been identified. Look up 'Francesco Guerra' in GoogleThis author has not been identified. Look up 'Letizia Tanca' in GoogleThis author has not been identified. It may be one of the following persons: Look up 'Yannis Velegrakis' in Google