Since crossover operator plays a vital role in genetic algorithms (GAs), several crossover operators have been proposed for the travelling salesman problem, which are then modified for the quadratic assignment problem (QAP). In this paper, we modify the sequential constructive crossover (SCX) operator for a simple GA to find heuristic solution to the QAP. Efficiency of the proposed GA using SCX...

The quadratic assignment problem (QAP) maybe was for a long time the one among the prominent NP-hard combinatorial optimization problems about which the fewest polyhedral results had been known. Recent work of Rijal (1995) and Padberg and Rijal (1996) has on the one hand yielded some basic facts about the associated quadratic assignment polytope, but has on the other hand shown that \naive" inv...

New lower bounds for the quadratic assignment problem QAP are presented. These bounds are based on the orthogonal relaxation of QAP. The additional improvement is obtained by making eecient use of a tractable representation of orthogonal matrices having constant row and column sums. The new bound is easy to implement and often provides high quality bounds under an acceptable computational eeort.

The quadratic assignment problem (QAP) is very challengeable and interesting problem that can model many real-life problems. In this paper, we will simply discuss the meaning of quadratic assignment problem, solving techniques and we will give a survey of some developments and researches.

This paper presents HAS-QAP, an hybrid ant colony system coupled with a local search, applied to the quadratic assignment problem. HAS-QAP uses pheromone trail information to perform modifications on QAP solutions, differently from more traditional ant systems that use pheromone trail information to construct complete solutions. HAS-QAP is analysed and compared with some of the best heuristics ...

We investigate a polytope (the QAP-Polytope) beyond a \natural" integer programming formulation of the Quadratic Assignment Problem (QAP) that has been used successfully in order to compute good lower bounds for the QAP in the very recent years. We present basic structural properties of the QAP-Polytope, partially independently also obtained by Rijal (1995). The main original contribution of th...

Program libraries are one tool to make the cooperation between specialists from various elds successful: the separation of application-speci c knowledge from applicationindependent tasks ensures portability, maintenance, extensibility, and exibility. The current paper demonstrates the success in combining problem-speci c knowledge for the quadratic assignment problem (QAP) with the raw computin...

This paper presents HAS-QAP, a hybrid ant colony system coupled with a local search, applied to the quadratic assignment problem. HAS-QAP uses pheromone trail information to perform modifications on QAP solutions, unlike more traditional ant systems that use pheromone trail information to construct complete solutions. HAS-QAP is analysed and compared with some of the best heuristics available f...

Scope and Purpose There are a vast number of practical design and resource-allocation problems, in many different fields, where the decision to be made is a matching (or assignment) of items in one set to items in another, disjoint set. If the costs associated are simply constants for each possible pairing, this is the classical " Assignment Problem " , for which good algorithms have been known...

In this paper, we show that the quadratic assignment problem (QAP) can be reformulated to an equivalent rank constrained doubly nonnegative (DNN) problem. Under framework of difference convex functions (DC) approach, a semi-proximal DC algorithm is proposed for solving relaxation DNN whose subproblems solved by augmented Lagrangian method. We generated sequence converges stationary point corres...