A Comparison of Analytic and Experimental Goal Regression for Machine Learning

Recent research demonstrates the use of goal regression as an analytic technique for learning search heuristics. This paper critically examines this research and identifies essential applicability conditions for the technique. The conditions that operators be invertible and that the domain be closed wi th respect to the inverse operators severely l imi t the use of analytic goal regression. In those restricted domains which satisfy the applicability conditions, analytic goal regression only discovers required preconditions for operator application. Discovering pragmatic preconditions is beyond the capability of the technique. An alternative, called experimental goal regression, is defined which approximates the results of analytic goal regression wi thout suffering from these limitations.