Predicate-formation for synthesizing LISP code

A novel technique for predicate-formation is given. It is useful for generation of LISP programs from the I/O examples. The top-level elements of I/O lists can be atoms or lists of arbitrary structure, and can be put into two groups, on which different actions are taking place. The predicate generated yields true for elements of one group, while false for other elements. The technique is mainly useful in generating branching code