Benci, Vieri; Fortunato, Donato Estimate of the number of periodic solutions via the twist number. (English) Zbl 0881.34063 J. Differ. Equations 133, No. 1, 117-135 (1997). The authors consider the dynamical system of the form \[ \ddot x+ V'(x)=0, \] where \(x\in\mathbb{R}^N\), \(V\in C^2(\mathbb{R}^N,\mathbb{R})\) and the gradient \(V'(x)\) is asymptotically linear for \(|x|\to\infty\). It is assumed also that the potential \(V\) has a finite number of non-degenerate critical points \(z_1,\dots,z_n\).Starting from the positive eigenvalues of the Hessian matrices \(V''(z_i)\), the authors define the global twist number of the system and using this characteristic they give a lower estimate for the number \(n(T)\) of non-constant \(T\)-periodic solutions of the system for \(T\) sufficiently large. Reviewer: V.V.Obukhovskij (Voronezh) Cited in 11 Documents MSC: 34C25 Periodic solutions to ordinary differential equations 37-XX Dynamical systems and ergodic theory Keywords:dynamical system; global twist number; \(T\)-periodic solutions PDFBibTeX XMLCite \textit{V. Benci} and \textit{D. Fortunato}, J. Differ. Equations 133, No. 1, 117--135 (1997; Zbl 0881.34063) Full Text: DOI