
16.6 Budget Constraints 235
In many situations, there may be some natural structure that limits the set
of packages that bidders consider valuable, thereby simplifying the allocation
problem. Let us examine a few examples.
As a first step, notice that the allocation problem is simple in two extreme
cases. First, if all the objects are identical so that as in Chapter 12 each buyer
cares only about the number of objects he receives, then efficient allocations are
relatively simple to determine. Second, if the objects are completely unrelated
so that the value of a package is just the sum of the values of the objects in
that package—the case of additive