Algebraic solution of weighted minimax single-facility constrained location problems

Nikolai Krivulin

Published 2018-10-24Version 1

We consider location problems to find the optimal sites of placement of a new facility, which minimize the maximum weighted Chebyshev or rectilinear distance to existing facilities under constraints on the feasible location domain. We examine a Chebyshev location problem in multidimensional space to represent and solve the problem in the framework of tropical (idempotent) algebra, which deals with the theory and applications of semirings and semifields with idempotent addition. The solution approach involves formulating the problem as a tropical optimization problem, introducing a parameter that represents the minimum value in the problem, and reducing the problem to a system of parametrized inequalities. The necessary and sufficient conditions for the existence of a solution to the system serve to evaluate the minimum, whereas all corresponding solutions of the system present a complete solution of the optimization problem. With this approach, we obtain a direct, exact solution represented in a compact closed form, which is appropriate for further analysis and straightforward computations with polynomial time complexity. The solution of the Chebyshev problem is then used to solve a location problem with rectilinear distance in the two-dimensional plane. The obtained solutions extend previous results on the Chebyshev and rectilinear location problems without weights.