IE Seminar: “An exact solution approach for the inventory routing problem with time windows”, Gizem Özbaygın, 1:30PM March 15 2024 (EN)

Speaker: Gizem Özbaygın (Sabancı University, Faculty of Engineering and Natural Sciences)

Title: An exact solution approach for the inventory routing problem with time windows

Date: March 15, 2024 (Friday)

Time: 13:30 – 14:30
Place: EA-409

The inventory routing problem (IRP) is an integrated inventory and transportation planning problem. It aims to optimize the replenishment schedules of various retailers and the routing decisions of a supplier over a finite planning horizon typically spanning multiple periods. Traditionally, retailers are assumed to accept deliveries at any time within a period, but this assumption may not align with real-world constraints. Retailers often have operational limitations that dictate specific delivery time windows. Hence, we delve into the IRP with time windows, developing an exact algorithm tailored to this realistic problem variant. Our approach introduces a novel formulation and employs a branch-price-and-cut algorithm, which is the first exact method crafted explicitly for solving the IRP with time windows (IRPTW). Our formulation integrates arc and route-based variables to simplify the structure of the pricing problems. We enhance our model with valid inequalities originally devised for the lot sizing problem, bolstering its effectiveness. Computational experiments conducted on various newly generated benchmark instances validate the efficacy of our algorithm. It efficiently produces optimal or highly satisfactory solutions for medium to large problem sizes within reasonable computation times.

Gizem Özbaygın is an Assistant Professor in the Industrial Engineering Program at Sabancı University since September 2017. She received her B.S. and Ph.D. degrees from Bilkent University Industrial Engineering Department in 2011 and 2017, respectively. Her dissertation was focused on the design and development of efficient optimization algorithms for solving several variants of the vehicle routing problem. During her Ph.D. studies, she spent a year at the H. Milton Stewart School of Industrial and Systems Engineering at Georgia Institute of Technology as a visiting student. She has a strong background in modeling and solving large-scale optimization problems with a particular focus on vehicle routing and scheduling. Gizem spent the 2022-2023 academic year in Canada working as a Senior Operations Research Scientist for 1QBit, a quantum computing software company based in Vancouver. She remains to be an advisor to 1QBit and is actively contributing to some of the company’s ongoing projects. Motivated by her recent involvement with 1QBit, she is highly interested in pursuing research in the use of quantum computing and more generally, physics-inspired alternatives to classical computing as a means to solve difficult optimization problems.