Silverstein, G., & Pazzani, M. (1991).  Relational clichecs: Constraining constructive induction
 during relational learning.  Proceedings of the Eighth International Workshop on Machine
 Learning (pp. 203-207).  Evanston, IL:  Morgan Kaufmann.
 We discuss an approach to creating new terms during the induction of Horn clauses.  The new terms enable a
 selective form of look-ahead during hill-climbing search.  This look-ahead is needed because a conjunction of
 literals may be useful while each literal individually may not appear to be useful.   We exploit knowledge of
 common patterns of conjunctions to avoid the necessity of testing all
pairs of conjunctions.