 In order to illustrate these postulates, we consider the following example, due to (Konieczny and Pino Pérez 1999). A group of flats co-owners wish to improve their condominium. At the meeting, the chairman proposes to build a tennis court, a swimming pool or a private parking. He also points out that building two of the three options will lead to a significant increase of the yearly maintenance expenses (this corresponds to the IC). 