I found by chance Maeder's public articles about Logic Programming with Mathematica at the following links:
Logic Programming I: The Interpreter and Logic Programming II: Applications
The first uses the packages LogicProgramming.m, Unify.m, Lisp.m, DAG.m .
The second uses also the packages FSA.m, NIM.m, JurassicPark.m .
The packages are referred to be contained in some "electronic supplement"
Does anybody know if they are available for download (and where, in that case) ? Better to know before trying to study the articles. Thanks.
It looks like they are available from the Mathematica Journal web site. I looked up the issue where the first article came from, and the electronic supplements are available via a link at the top. The second issue is here.
Mathematica by nature acts like Lisp. a variety of Lisp languages are free (ie, via Ubuntu which is a module for Windows 10 you can check out). Lisp was in older journals as a language conducive to artificial intelligence programming.
Lisp would only restrict what you are used to being able to do with lists and expressions. Studying an introduction to lisp book would enlighten you as to a style of node traversal programming, though.
(problems with lisp: few use it, it has a high learning curve. few drivers - meaning it will be limited to text output - no graphics. the versions that are "very reliable" and standardized are non-free, the free versions change standards so that older programs / examples will crash)
Mathematica 11.3 has an immense wealth of DAG, some which likely were (began) by Roman Maeder.
Mathematica 11.3 has extended logic solving (symbols, functions, tutorials).
The old articles are interesting but no longer needed if your running any recent version of Mathematic. It was written back for Version 2.2. First version i owned was 4.0 in the (latter 90's) :)
Prolog is also something Mathematica does you won't need.