A generalized approach to modeling the hierarchical location-allocation problem

The hierarchical location-allocation problem is generalized in four respects: different hierarchical relationships are allowed to be simultaneously present; capacity constraints are placed on service types and service groups; a flexible (fixed and variable) cost structure is used; and interservice referrals are permitted. These four generalizations are captured in a mixed-integer linear programming model which is shown to subsume less general formulations documented in the literature. A comprehensive example is included to demonstrate the model´s capabilities