Chapter 3 describes a number of algorithms for the processing of symbolic rules. The following links point to software that can be used to explore some of the ideas and techniques for rule representation and processing.
Paul Grahamís inference production system in the Lisp language.
A commented version of Grahamís inference program, extended to allow entry of a list of facts
Lisp code for a slightly larger version of the genealogy example discussed in chapter 3, using the extended version of Grahamís inference program