Key points are not available for this paper at this time.
An electron gas with short-range interactions is considered in the presence of a uniform magnetic field. It is shown that (1) the cyclotron resonance frequency is independent of the interaction; (2) for a two-dimensional gas, the de Haas-van Alphen period is independent of the interaction. The low-lying excited states are briefly discussed.
W. Kohn (Tue,) studied this question.