Predicate Invention in Inductive Program Synthesis

In Inductive Logic Programming, predicate invention is the process of introducing a hitherto unknown predicate, and its description, into the description of the currently learned predicate. This is only necessary when a finite axiomatization of the current predicate is otherwise impossible, in which case the description of the invented predicate is recursive. So necessary predicate invention is a program synthesis task, and had thus best be done by a synthesizer rather than by a general purpose learner, because one can then re-use the vast body of knowledge about recursive algorithm design. Taking a schema-guided approach, I show how predicate invention can be performed (if not avoided) by intelligent re-use from structured background knowledge, by necessarily successful intelligent dialogue with the user, and by structural or computational generalization of the original problem.