An expert system is used to recommend a customized solution for a customer. The expert system includes a set of scenarios each of which includes default facts and is associated with a detailed rule base that when applied in isolation to the default facts fully determines a prototype solution. A particular scenario is selected from the set based at least on user input. A customized solution is generated by applying the detailed rule base associated with the particular scenario to facts based at least on the user input and any default facts of the particular scenario that complement and do not conflict with the facts that are based at least on the user input. The customized solution is iteratively refined.