The Storage Location Assignment Problem (SLAP) aims at allocating
the products to the slots in a warehouse, minimizing both the handling
costs and penalties and maximizing the space utilization. The allocation
mechanism follows the principle that the highly demanded products are
allocated in slots next to the I/O doors in order to reduce the total handling
times (especially during the picking activity).
Among the several proposed strategies, the dedicated storage policy always
assigns a fixed number of slots to the same product type. It is very easy
to be implemented, but it has the disadvantage that an empty slot cannot
be used for a different product type. For this reason, it leads to a waste of
space especially in cases where the goods are subjected to the seasonality factor
[Lee 2005]. To overcome this limit, in [Goetschalckx and Ratliff 1990],
a heuristic based on the Duration of Stay (DOS) concept is proposed. In
particular, DOS(i) represents how long the item i stays in the warehouse.
The items with the lowest DOS (i.e., highly demanded) are then assigned
to slots next to the I/O doors.