It is very common for the coefficients Cijkl to be derived from the product of other coefficients tik and djl so that Cijkl = tikdjl. Firstly, we consider S to be a set of N factories and T to be a set of N cities. The problem is to locate one factory in each city and to minimize total communication costs between factories. The communication costs depend on (i) the frequency of communication between each pair of factories, and (ii) the distances between the two cities where each pair of factories is located. Clearly, some factories will have little to do with each other and can be located far apart at little cost. On the other hand, some factories may need to communicate a lot. The cost of communication will depend on the distance apart. In this application, we can interpret the coefficients tik and dji as follows: tik is the frequency of communication between factories i and k; dj is the cost per unit of communication between cities j and 1 (clearly, this will be related to the distance between j and 1). Obviously, the cost of communication between the factories i and k, located in cities j and 1, will be given by Cijkl = tikdjl. The total cost is therefore represented by the objective function. This problem will be represented using two .txt files, namely, frequencies.txt and distances.txt. The first file contains the frequencies (i.e., tik) in N lines with N values. It contains the following lines for an example problem: frequencies.txt 25 63 34 52 63 39 21 57 34 21 10 66 52 57 66 63 The second file contains the distances (i.e., d;) in N lines with N values. It contains the following lines for an example problem: distances.txt 44 26 68 66 26 52 51 62 68 51 96 60 66 62 60 83