Mao, Rui; Wang, Duo Jumping property of Lyapunov values. (English) Zbl 0847.34032 Adv. Math., Beijing 25, No. 1, 93-94 (1996). For distinguishing between center and focus in a planar vector field described by (1) \(\dot x=- y+ f(x, y)\), \(\dot y= x+ g(x, y)\), one has to calculate the Lyapunov values of (1). A convenient way to do this is to change (1) to its equivalent complex form (2) \(\dot z= iz+ F(z, \overline {z})\). In [Random Comput. Dyn. 2, 261-277 (1994; Zbl 0829.34023)] the authors introduced the notion of \(k\)th standard Lyapunov value \(L_k (F)\). In this paper they list (without proofs) certain properties of the values \(L_k (F)\). Reviewer: W.Müller (Berlin) MSC: 34C05 Topological structure of integral curves, singular points, limit cycles of ordinary differential equations Keywords:center and focus; planar vector field; standard Lyapunov value Citations:Zbl 0829.34023 PDFBibTeX XMLCite \textit{R. Mao} and \textit{D. Wang}, Adv. Math., Beijing 25, No. 1, 93--94 (1996; Zbl 0847.34032)