We report on a growing class of assignment problems that are increasingly of interest and very challenging in terms of the difficulty they pose to attempts at exact solution. These problems address economic issues in the location and design of factories, hospitals, depots, transportation hubs and military bases. Others involve improvements in communication network design. In this article we survey the latest and best methods available for solving exactly these difficult problems and suggest a taxonomy that provides a framework for combining existing solution methods and sets of computer tools that can be modified and extended to make inroads in solving this growing class of optimization problems.
This article is to be printed in the International Transactions on Operations Research.