This research was partially supported by the Russian Foundation for Basic Research under grant No. 95-011-8701 and by Canadian
grant No. 0GP0156833.
Institute for System Studies, Russian Academy of Sciences. Translated from Funktsional'nyi Analiz i Ego Prilozheniya, Vol.
31, No. 4, pp. 89–91, October–December, 1997.
Translated by A. I. Shtern