Classes of quadratic assignment problem instances: isomorphism and difficulty measure using a statistical approach Original Research Article

In this work, we introduce the variance expression for quadratic assignment problem (QAP) costs. We also define classes of QAP instances, described by a common linear relaxation form. The use of the variance in these classes leads to the study of isomorphism and allows for a definition of a new difficulty index for QAP instances. This index is then compared to a classical measure found in the literature.