We address the following sensor selection problem. We assume that a dynamic system possesses a certain property, call it Property D, when a set G of sensors is used. There is a cost cA associated with each set A of sensors that is a subset of G. Given any set of sensors that is a subset of G, it is possible to determine, via a test, whether the resulting system-sensor combination possesses Property D. Each test required to check whether or not Property D holds incurs a