. . . "I have 2 variables for example assume {a,b} I have n parentheses and r locations in each parentheses - inside each parentheses variables are summed and the parentheses are are multiplied with each other. example of n = 3 , r = 3 - ( _ + _ + _ ) * (_ + _ + _ ) * (_ + _ + _ ) since {a.b} are just 2 variables, this mean it can be repeated many times within the parentheses." .