A note on a polynomial time solvable case of the quadratic assignment problem

Abstract

We identify a class of instances of the Koopmans-Beckmann form of the Quadratic Assignment Problem that are solvable in polynomial time. This class is characterized by a path structure in the flow data and a grid structure in the distance data. Chr18b, one of the test problems in the QAPLIB, is in this class even though this feature of it has not been noticed until now.