?? . [0092] Here, B is a function of F, P, and N. Since such a function would only be logarithmic with respect to (F/P+N), an approximate analysis could treat B as being independent of P (one possible approximation for B ??? ??? is ??? ??? ??? log ??? ??? N 4 ??? ) . [0093] A minimum this total expected time as a function of P occurs at P = cd ??? ??? F ??? ??? B c ??? ??? F ??? ??? ?? = d ??? ???