Rule Engine, Expert system

As defined in Wikipedia, Rule Engine can seperate into

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•There are mainly two different types of rule engines. The first one is rule engines with so-called production/ inference rules. These types of rules are used to answer complex questions and infer answers. For example, such a rule could answer the question: "Should this customer be allowed a mortgage?".

•The other type of rule engines are those implementing reaction rules. The reactive rule engines are used to detect and react to interesting patterns of events occurring. For example a reactive rule engine could be used to alert a manager when certain items are out of stock.

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