I have already used prolog in my philosophy. I have started preparing to use Xlisp and OPS5. I found a more current version of Xlisp than I had and compiled it & it seemed OK. (I also have a version of common lisp). I hope to get OPS5 working with it. Then I hope to be able to generate the “databases” I will use with Prolog to illustrate my philosophy. I suppose I should check for a new version of OPS5 as well. I had my version working in the 80’s. (On Amiga).