We consider the single item lot-sizing problem with capacities that are non-decreasing overtime. When the cost function is i) non-speculative or Wagner-Whitin (for instance, constantunit production costs and non-negative unit holding costs), and ii) the production set-upcosts are non-increasing...

Providing a good formulation is an important part of solving a mixed integer program.We suggest to measure the quality of a formulation by whether it is possible tostrengthen the coefficients of the formulation. Sequentially strengthening coefficientscan then be used as a tool for improving...