Facility location applications are concerned with the location of one or more facilities in a way that optimizes a certain objective such as mini- mizing transportation cost, providing equitable service to customers, cap- turing the largest market share, etc. Facility location problems give rise to challenging geometrical and combinatorial problems. The research on facility location problems spans many research fields such as operations re- search/management science, industrial engineering, geography, economics, computer science, mathematics, marketing, electrical engineering, urban planning,...