Indices | |
i , j | index of items, i, j = 1, ..., N |
o | index of orders, o = 1, ..., O |
m | index of pods, m = 1, ..., M |
Parameters | |
N | total number of items |
O | total number of orders |
M | total number of pods |
Q | number of inventory bins in one pod; Q=8 in this article |
Bi | number of inventory bins for the item i needed to be assigned |
Sij | similarity value between the item i and j, it is equal to the support count between item i and j |
S | item similarity matrix |
Decision variables | |
xim | xim = 1 if the item i is put on the pod m; |
xim = 0 , otherwise | |
yim | number of inventory bins that item i occupies on the pod m |