Test-assignment: a quadratic coloring problem

We consider the problem of assigning the test variants of a written exam to the desks of a classroom in such a way that desks that are close-by receive different variants. The problem is a generalization of the Vertex Coloring and we model it as a binary quadratic problem. Exact solution methods based on reformulating the problem in a convex way and applying a general-purpose solver are discussed as well as a Tabu Search algorithm. The methods are extensively evaluated through computational experiments on real-world instances. The problem arises from a real need at the Faculty of Engineering of the University of Bologna where the solution method is now implemented.