Case 1. m < kz/2 For Xt1 = m < (kz/2) and Xt = i where
1 6 i 6 2m 1, the picker will not reach bin j, j < i or
j > 2m i, because he/she always selects the shortest
route. This implies that ðt 1Þth order does not include
any item in bin j. When the items in bin (2m i) are listed
in the ðt 1Þth order, the probability that the picker first
goes to bin (2m i) then proceeds to bin i is 1/2 since the
distance between bin (2m i) and bin m is equal to the
distance between bin i and bin m. Thus,