may be any backward chaining goal. If
is used in a forward chaining pre-condition,
may only contain expressions normally allowed in forward chaining pre-conditions (object base references and lisp tests).
goal succeeds if the
contained within fail.
(not (truck ?truck driver ?driver) (test ?driver))
KnowledgeWorks and Prolog User Guide (Macintosh version) - 4 Apr 2005