OPS5
A programming language for rule-based production systems. A rule consists of pre-condition(s) and a resulting action.
The system checks its working memory to see if there are rules whose pre-conditions are satisfied, if so, the action in one selected satisfied rule is executed.
There is a public domain implementation of an OPS5 interpreter written by Charles L. Forgy <forgy@cs.cmu.edu> in 1977. It was first implemented in Lisp and later in BLISS. It was also ported to Common Lisp by George Wood and Jim Kowalski.
CLIPS is a language for writing expert systems, with some of the capabilities of OPS5.
See also C5, OPS83, OPS4, OPS5+, OPS83.
Inference Engine Tech, Cambridge MA.
An OPS5 interpreter in Common LISP.
A version by Mark Kantrowitz. <mkant+@cs.cmu.edu>.
["Programming Expert Systems in OPS5", L. Brownston et al, A-W 1985].
["An OPS5 Primer", Sherman et al, comes with OPS5 for DOS].
["Rule-Based Programming in the Unix System", G.T. Vesonder, AT&T Tech J 67(1), 1988].