Primal-Dual Variable Neighborhood Search for the Simple Plant Location Problem

The variable neighborhood search metaheuristic is applied to the primal simple plant location problem and to a reduced dual obtained by exploiting the complementary slackness conditions. This leads to (i) heuristic resolution of (metric) instances with uniform fixed costs, up to n = 15,000 users and m = n potential locations for facilities with an error not exceeding 0.04%; (ii) exact solution of such instances with up to m = n = 7, 000; (iii) exact solution of instances with variable fixed costs and up to m = n = 15, 000.