Computational Comparison of Stand-Centered Versus Cover-Constraint Formulations

Abstract

The area restriction model for harvest scheduling problems can be formulated using mixed integer programs. The three different formulation types are cluster packing, cell aggregation, and the assignment formulation. Within the cell aggregation subgroup there is an exact formulation, the cover constraint (CC) approach; and an inexact formulation, the stand-centered approach. The cover constraint formulation has significantly more constraints than the stand-centered formulation. A computational comparison between these two methods is completed using cutting planes and constraint combinations using the CPLEX solver package. The CC approach as cutting planes was superior based on solution time. If formulation time were included with solution time, then the CC approach remains superior. The maximum harvest area is a significant factor of solution time. In addition, the percentage of total cutting planes used to solve the problem was examined.

Keywords:

• area restriction model
• harvest scheduling
• optimization