Abstract
This paper deals with the preliminary selection of Lyapunov function candidates (LFC) for semi-state systems (SSS). The problems that appear in the process of the evaluation of the total time derivative of an LFC along the motions of SSS are discussed. As a result some convenient classes of the LFC are determined. Some concrete hints on the methodology of the construction of LFC are given. Also, the well-known formula of Yoshizawa (1966) for the calculation of the upper right-hand Dini derivative of non-differentiable LFC is extended and generalized to cover the problems of SSS. The results are illustrated through the analysis of general linear RLCMT unforced electrical networks and a non-linear feedback system.