9406751 Antoy The object of this project is to develop the theory and applications of a narrowing strategy that extends the recently discovered notion of needed narrowing for inductively sequential systems to constructor based strongly sequential and weakly orthogonal systems. Needed narrowing will be implemented as it applies to functional logic languages for a prototypical and portable integration of function and predicates. The efficiency of this implementation will be compared with that of other implementations of narrowing previously proposed for the same purpose. ***