The article presented here reflects a scientific work of more than ten years. During this too long period I enjoyed useful discussions with many researchers and scientists. I offer my apologies for being unable to thank every single one of them here explicitly. Valuable hints of Dr.A.Klodt, Prof.Z.Lipecki, and Prof.B.Peleg improved the work. The help­ ful conversations with and the hospitality of Prof.T.E.Armstrong and Prof.M.K.Richter are gratefully acknowledged. The instructions in macro­ economics by Prof.G.Gabisch were very helpful for my principal reasoning. I am indebted to my teacher and supervisor Prof.D.Pallaschke, who moti­ vated and supported always our research. Especially I have to thank Prof.S.Rolewicz from the Polish Academy of Sciences for the great help and encouragement. The first three chapters of this paper correspond to my Habilita­ tionsarbeit submitted to the Faculty of Economics of the University of' Karlsruhe in February 1987. I am indebted to Prof.W.Eichhorn, in particular for his seminars. The effective support by our chairman Prof.R.Henn is gratefully ac­ knowledged. I wish to express my gratitude and my admiration to Prof.Dr.h.c. mult.W.Krelle, editor of this scientific series.