The relativistic semi-group,Lorentz group,and tachyons. I

It is claimed that the current interest of tachyons and some of their unusual properties may be the result of an insufficient mathematical formalism based on Lorentz groups. The introduction of tachyons requires not only a generalization of the principle of causality, but also an extension of the principle of relativistic invariance. A method is proposed to remove a number of problematic cases in the treatment of tachyons.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 5, pp. 85–88, May, 1976.The author wishes to express his appreciation to D. D. Ivanenko for consideration and constructive criticism.