1. We are having troubles with the Scheme-to-C compiler and so have
been unable to produce a working ps5-sci. So, just use sci and do
(load "load.sc").
2. The (parse) function only prints something when it finds a legal
parse using the very small grammar defined in grammar.scm. If you
want to see the operation of the backward chainer, replace the line:
(set! *verbose?* #f) in the definition of parse with (set! *verbose?*
#t). Then you will see the rule firing attempts.
Tomas