A problem in which units of a certain product are to be transported from a number of factories to a number of retail outlets in a way that minimizes the total cost. For example, suppose that there are m factories and n retail outlets and that the transportation costs are specified by an m×n matrix [c_ij], where c_ij is the cost, in suitable units, of transporting one unit of the product from the ith factory to the jth retail outlet. Suppose also that the maximum number of units that each factory can supply and the minimum number of units that each outlet requires are specified. By introducing suitable variables, the problem of minimizing the total cost can be formulated as a linear programming problem.