Quadratic Assignment Problem (Model, Applications, Solutions): Review Paper

n operations research, Quadratic Assignment Problem (QAP) is a significant combinatorial optimization problem. When the size of the QAP problem increases, it becomes impossible to solve the problem in polynomial time. Several practical problems such as hospital and campus layout, allocation of gates to airplanes in airports and electrical backboard wiring problems can bemodeled as QAP. The QAP model seeks to identify the optimal distribution of N facilities to N locations in a way that minimizes the total traveling cost based on the distance between every pair of a location and the amount of traffic between every pair of facilities of organizational units within a building. Against this background, there are two main approaches have been suggested to deal with QAP, and they are, the Exact and Approximate (Heuristic and Metaheuristic) approaches. The exact approach provides a global optimal solution for the small size of QAP, while the approximate approaches can find the optimal or a near-optimal solution at a reasonable time for large-sized QAP. The objectives of this study are as follows: (i) To analysis the QAP model, (ii) To conduct a comprehensive survey of the methods that have been used to solve the QAP model, (iii) To identify the issues and limitations of the methods in (ii), and (iv) to explore the best approach that can be used in enhancing the solutions of QAPmodel within a reasonable time based on the accuracy of algorithm. The results show that the hybrid metaheuristic approach has the capability of finding the best results within a reasonable time for the large sized problem

Of keyboards and beyond - optimization in human-computer interaction

In this thesis, we present optimization frameworks in the area of Human-Computer Interaction. At first, we discuss keyboard layout problems with a special focus on a project we participated in, which aimed at designing the new French keyboard standard. The special nature of this national-scale project and its optimization ingredients are discussed in detail; we specifically highlight our algorithmic contribution to this project. Exploiting the special structure of this design problem, we propose an optimization framework that was efficiently computes keyboard layouts and provides very good optimality guarantees in form of tight lower bounds. The optimized layout that we showed to be nearly optimal was the basis of the new French keyboard standard recently published in the National Assembly in Paris. Moreover, we propose a relaxation for the quadratic assignment problem (a generalization of keyboard layouts) that is based on semidefinite programming. In a branch-and-bound framework, this relaxation achieves competitive results compared to commonly used linear programming relaxations for this problem. Finally, we introduce a modeling language for mixed integer programs that especially focuses on the challenges and features that appear in participatory optimization problems similar to the French keyboard design process.Diese Arbeit behandelt Ansätze zu Optimierungsproblemen im Bereich Human-Computer Interaction. Zuerst diskutieren wir Tastaturbelegungsprobleme mit einem besonderen Fokus auf einem Projekt, an dem wir teilgenommen haben: die Erstellung eines neuen Standards für die französische Tastatur. Wir gehen auf die besondere Struktur dieses Problems und unseren algorithmischen Beitrag ein: ein Algorithmus, der mit Optimierungsmethoden die Struktur dieses speziellen Problems ausnutzt. Mithilfe dieses Algorithmus konnten wir effizient Tastaturbelegungen berechnen und die Qualität dieser Belegungen effektiv (in Form von unteren Schranken) nachweisen. Das finale optimierte Layout, welches mit unserer Methode bewiesenermaßen nahezu optimal ist, diente als Grundlage für den kürzlich in der französischen Nationalversammlung veröffentlichten neuen französischen Tastaturstandard. Darüberhinaus beschreiben wir eine Relaxierung für das quadratische Zuweisungsproblem (eine Verallgemeinerung des Tastaturbelegungsproblems), die auf semidefinieter Programmierung basiert. Wir zeigen, dass unser Algorithmus im Vergleich zu üblich genutzten linearen Relaxierung gut abschneidet. Abschließend definieren und diskutieren wir eine Modellierungssprache für gemischt integrale Programme. Diese Sprache ist speziell auf die besonderen Herausforderungen abgestimmt, die bei interaktiven Optimierungsproblemen auftreten, welche einen ähnlichen Charakter haben wie der Prozess des Designs der französischen Tastatur