I was mostly imagining legacy banking systems are the main use-cases for stuff like this, and was a little surprised to see Apache adopted Drools in 2023[1].

In case anyone might be able to answer..

What are some of the biggest rule systems deployed in the wild, and are any of them recent? Since it seems like this is mostly about first order logic.. do any of these rule-engines actually out perform all the modern work on SMT solvers and other theorem-provers? Same question for this more probabilistic Rete-OO flavor.. isn't there already some faster and more generic engine available that handles this kind of thing as a special case?

[1] https://en.wikipedia.org/wiki/Drools#Drools_in_Apache_Kie [2] https://en.wikipedia.org/wiki/Rete_algorithm#Rete-OO