The Munich Rent Advisor

The city government of Munich regularly publishes a booklet called the “Mietspiegel” (MS). The MS basically contains a verbal description of an expert system. It allows to calculate the estimated fair rent for a flat. By hand, one may need a weekend to do so. With our computerized version, “The Munich Rent Advisor”, the user just fills in a form in a few minutes and the rent is calculated immediately. We also extended the functionality and applicability of the MS so that the user need not answer all questions of the form. The key to computing with partial information was to use constraint technology. We rely on the internet, and more specifically the World-Wide-Web (WWW), to provide this service to a broad user–group, the citizens of Munich. Several thousand people haved used our service during a trial phase in winter 95/96. To process the answers from the questionnaire and return its result, we wrote a simple stable special-purpose web-server directly in ECLPS.