Last summer, after increasing the attendance of our seminar to the maximum number allowed by the local facilities, which meant about forty persons, we had the regrettable obligation to refuse quite a few later applications for attendance. This meant already that we had to hold numerous workshops in two different halls, in order to give everyone a chance to show his work and not crowd the halls too much. Because of this, and because we do not wish to go beyond this size of attendance, we have decided to hold a winter seminar, but not in La Chapelle St André (Burgundy), where the season creates harsh living conditions, but in Argenteuil, at the seat of the I.P.P., in the suburbs of Paris. Of course, persons that were denied attendance at the summer seminar will have a priority. Again for practical reasons, we do not wish to receive too many persons, in order for the seminar to remain a seminar and not become a conference. So we intend to receive maximum 25-30 persons, inte...