Extensions of the Multi-Period Facility Phase-Out Model: New Procedures and Application to a Phase-In/Phase-Out Problem

Abstract

This paper extends the multi-period facility phase-out model of Roodman and Schwarz in two ways: First, the branch-and-bound procedure is improved by the incorporation of two new lower bounds, which are both easier to obtain and more powerful than those originally proposed, and the addition of two new simplifications. Second, the model itself is generalized to solve a phase-in/phase-out problem. The improved branch-and-bound procedure is directly applicable to the static facility location models of Efroymson and Ray and Khumawala, and has consistently solved sample static problems faster than the methods proposed by these authors.