Valid inequalities for the problem of optimizing a nonseparable piecewise linear function on 0-1 variables

In many procurement and transportation applications, the unit prices depend on the amount purchased or transported. This results in piecewise linear cost functions. Our aim is to study the structure that arises due to a piecewise linear objective function and to propose valid inequalities that can be used to solve large procurement and transportation problems. We consider the problem of optimizing a nonseparable piecewise linear function on 0-1 variables. We linearize this problem using a multiple-choice model and investigate properties of facet defining inequalities. We propose valid inequalities and lifting results.