CEF.UP – MaR Webinar

Tuesday – March 23^rd, 2021 6:30 p.m. – 7:30 p.m.

“Economic lot sizing problem with remanufacturing option“

Ashwin Arulselvan – University of Strathclyde (UK)

Area: Operations and Logistics

Abstract:

“In a single item dynamic lot-sizing problem, we are given a time horizon and demand for a single item in every time period. The problem seeks a solution that determines how much to produce and carry at each time period, so that we will incur the least amount of production and inventory cost. When the remanufacturing option is included, the input comprises of returned products at each time period that can be potentially remanufactured to satisfy the demands, where remanufacturing and inventory costs are applicable. For this problem, we first show that it cannot have a fully polynomial time approximation scheme (FPTAS). We then provide a pseudo-polynomial algorithm to solve the problem and show how this algorithm can be adapted to solve it in polynomial time, when we make certain realistic assumptions on the cost structure. A lot of questions remain open for generic cost structure.

In the second half of the talk, we are interested in the robust version of the problem. We assume that the demands and returns are uncertain and we employ the approach used by Bertsimas and Thiele to model the uncertainty set. We then provide a computational approach to solve the problem assuming the demands and returns belong to this uncertainty set. The approach can be viewed as a variant of Benders’ decomposition. The complexity of the subproblem even in the simplest case remains open.”