Backward chaining involves trying to prove a given goal by using rules to generate sub-goals and recursively trying to satisfy those. The KnowledgeWorks backward chaining engine is an extension of the LispWorks Common Prolog system which can match directly over KnowledgeWorks CLOS objects (the object base). All the standard Common Prolog facilities and built in predicates are available. For more detailed information the reader is referred to the Common Prolog. Note that all the different ways of proving a particular goal are defined together in the same form.
KnowledgeWorks and Prolog User Guide (Unix version) - 6 Dec 2011