In my country, the Expert System class is mandatory, if you want to take the AI specialization in most universities. In class, I learned how to make a rule-based system, forward chaining, backward chaining, Prolog, etc.

However, I have read somewhere on the web that expert systems are no longer used.

Is that true? If yes, why? If not, where are they being used? With the rise of machine learning, they may not be as used as before, but is there any industry or company that still uses them today?

Please, provide some references to support your claims.


2 Answers 2


I would say Expert Systems is still being taught. For instance, if you look at some of the open courses like MIT's, there are still lectures on it.

Also, looking at the CLIPS documentation, you will find a couple of examples of usage from 2005.

What I suspect is that Expert Systems are now embedded with "normal systems" in practice. Hence it may be difficult to distinguish from systems used on a daily basis for diagnostics, etc. and not as popular as before.


Are there companies that still use expert systems?

There are still some expert system inference engines available in open source form, in particular CLIPS rules

A specialization of your question could be: what companies are using CLIPS in 2020 ?

I don't have any ideas, even if I did try in https://github.com/bstarynk/clips-rules-gcc

And the RefPerSys project is right now (in November 2020) discussing the idea of incorporating such rules in it.

Read of course quickly Jacques Pitrat's blog on http://bootstrappingartificialintelligence.fr/WordPress3/ and his last book (describing the design of an ambitious symbolic artificial intelligence system -CAIA- with expert system ideas) Artificial Beings The Conscience of a Conscious Machine (ISBN 9 781848211018) - his CAIA system is on https://github.com/bstarynk/caia-pitrat but there is absolutely no documentation, since Jacques Pitrat passed away in October 2019. His CAIA system was capable of generating all the 500KLOC of its C code from some kind of expert system rules (whose design is described in Jacques Pitrat's books and papers).

I am not a native English speaker (since I am French) but I heard that expert systems are called (in 2020) business rule management systems.

I heard that major banks in France (maybe BNP or Société Générale) are using such systems to decide to give some loan or some credit to persons and companies (in particular for people buying their flat - or a brand new automobile - with a bank credit and debt during dozen of years).

The French banking system is very opaque: you won't be able to understand their internal software, and banks are not publishing any document about the design of their software. At most they would publish the name of their AI systems, but nothing public about the software design.

According to rumors, Lexifi or Yseop might use some kind of very proprietary expert system technology and sell services with them. But their software tools are closed source and very proprietary.

Regarding expert system for games, see also recent papers by Professor Tristan Cazenave. He did use some kind of expert system technology for games.

My guess is that large Internet companies like Google or Amazon are using expert system technology inside their internal software (e.g. search engines). IBM Watson is rumored to use them also.

BTW, GNU make might be considered as some very crude expert system engine driving building of software artifact from source code.

  • $\begingroup$ You say several times that "is rumored". Maybe you should cite the articles that hypothesize that, otherwise, there's no way of knowing that some parts of this answer are correct. $\endgroup$
    – nbro
    Nov 23, 2020 at 14:21
  • 1
    $\begingroup$ It is not articles. It is meeting some people in person (e.g. at funerals of J.Pitrat or at some seminars). And I won't give more details (because I feel I am not allowed to) $\endgroup$ Nov 23, 2020 at 14:33

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