Retrieving Software Components That Minimize

Given a software library whose components are represented by formal specii-cations, we distinguish between two types of retrieval procedures: exact retrieval, whereby, given a query K, we identify all (and only) the library components that are correct with respect to K; approximate retrieval, which is invoked in case exact retrieval fails, and which (ideally) identiies the library components that minimize the required adaptation eeort (once such a component is retrieved, the eeort of adapting it to satisfy query K is minimal over the set of all the components of the library). To this eeect, we deene four measures of functional distance between speciications, and devising algorithms that minimize these measures over a structured set of components ; then we discuss to what extent these measures can be used as predictors of adaptation eeort.