Intelligent test selection for machine failure isolation using qualitative physics

Variables associated with hypotheses of a qualitative physics model are grouped into type I variables and type II variables, wherein any possible value measured for a type I variable is guaranteed to render at least one hypothesis inconsistent and some, but not all, possible values measured for a type II variable will render at least one hypothesis inconsistent. A test score, indicating the desirability of observing a variable, is calculated for each variable and the type I variable with the highest test score is chosen for observation unless no type I variables have a test score above a predetermined threshold, in which case the type II variable with the highest test score is chosen.