When I compare the books on expert systems in my library with the
production expert systems I know of, I note that there are few good
books on building expert systems in Prolog. Of course, the set of actual
production systems is a little small for a valid statistical sample, at
least at the time and place of this writing - here in Gennany, and in
the first days of 1989. But there are at least some systems I have seen
running in real life commercial and industrial environments, and not
only at trade shows. I can observe the most impressive one in my
immediate neighborhood. It is installed in the Telephone Shop of the
Gennan Federal PTT near the Munich National Theater, and helps configure
telephone systems and small PBXs for mostly private customers. It has a
neat, graphical interface, and constructs and prices an individual
telephone installation interactively before the very eyes of the
customer. The hidden features of the system are even more impressive. It
is part of an expert system network with a distributed knowledge base
that will grow to about 150 installations in every Telephone Shop
throughout Gennany. Each of them can be updated individually overnight
via Teletex to present special offers or to adapt the selection process
to the hardware supplies currently available at the local ware- houses.